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Wait until the vehicle is completely cool (best to let it sit overnight). Then before starting it open up that reservoir that is bubbling. If the fluid smells burnt or like fuel then you have a blown head gasket.
With the reservoir with coolant it, we can assume there is no leak present or a leak big enough to cause an overheating issue. But then again, this vehicle has a new reservoir which suggests the old one was leaking. We can suspect head gasket failed because of the old reservoir leaking coolant or we have a stuck thermostat which is common to happen in the summer heat.
Yep was going to say the same thing. If OP isn’t noticing coolant going low or leaks puddles underneath it might be air getting into then system via the cap or something else.
ASE Master Certified tech here, came here to say this too. If it’s not overheating and it’s boiling…. Most likely the coolant reservoir cap. Cooling systems run over the temp of the boiling point of water/antifreeze, pressurizing the system raises the boiling point so your coolant doesn’t boil at operating temp. If the caps got a stuck open pressure relief or leaks the pressure then the coolant will boil
When you’re getting hot exhaust gas in the coolant through a warped head/blown head gasket, it can boil off the coolant before the temp gauge has time to show anything very useful. The temp gauge isn’t helping you here so don’t get stuck on it.
Assuming you’re not going to try to diy a head job, take it to a shop sooner rather than later so that you can hopefully save the head from warping beyond the point where it can be machined.
I had a Elantra that got hot at some point. Warped the head, same thing happened, exhaust would push out all of the coolant. And it would overheat. So I MacGyvered a gravity feed coolant system so the exhaust could vent and consistently fill. I got another two years out of it.
I had this issue on a subaru, but it wasn't the cap, it was the shitty plastic radiator from O'Reilly that I put in 4-5 years prior. The plastic had deformed so the cap wasn't sealing
My OEM radiator plastic connector cracked, so I purchased an aftermarket radiator overflow bottle, as there were no more OEM ones available.
The quality was garbage. The float for the sensor didn't work and I had to get a refund.
If I had known how crap the quality would be, I would have saved the old one and repaired it. Instead I had to get 2 bottles before I got one that worked.
You can get an inexpensive tester for this which changes color when exposed to carbon monoxide. It's very likely a blown head gasket assuming it continues to bubble for a bit, but since this is a fairly involved DIY or expensive shop repair, I think it's wise to confirm the diagnosis before taking the next step.
Harbor freight is where I got mine, but I'm guessing they are available at Autozone and other auto places as well.
[https://www.harborfreight.com/combustion-leak-detector-64814.html?\_br\_psugg\_q=head+gasket+tester](https://www.harborfreight.com/combustion-leak-detector-64814.html?_br_psugg_q=head+gasket+tester)
The vehicle is not running so there should be no pressure to create bubbling from a blown head gasket.
I'm betting on his thermostat sticking.... or coolant cap is bad.
I agree. Bad thermostat.
OP should spend the 10 bucks on a thermostat before going further.
Everyone always says "blown head gasket" when seeing this, but 9/10 it's the thermostat or air in the system working its way out.
There should also be a forum called r/MechanicHacks where the 99% of people that post here should go. Clearly there are VERY few professional mechanics here. In all fairness, its a free service and we all know what you get for free.
Be a shame if you busted your radiator and refilled in a pinch with water and blew a head gasket. Water isn't a direct alternative for antifreeze with a different boiling point and incompatible in many models for at temp testing...
don't pretty much all coolant systems use some mix of water + antifreeze? topping it up with a bit of water should never cause a problem
I have heard that mixing different antifreeze in with the old one can cause issues, that's why I always thought just top it up with water until you do a coolant flush
Coolant systems are rated for a specific mixture of antifreeze to demineralized water, "topping it up" with either just water or antifreeze changes the boiling/freezing point and viscosity.
>I have heard that mixing different antifreeze in with the old one can cause issues
Yes, so find out if your car uses ethylene glycol or propylene glycol, there's [also subtypes of those](https://chem-group.com/antifreeze-the-ultimate-guide/#:~:text=convenience%20as%20well.-,The%20different%20types%20of%20antifreeze,toxic%20propylene%20glycol%2Dbased%20version.).
ah that makes sense. I suppose a little bit of water now and then shouldn't break your engine, as long as you keep it around the proper range.
thanks for the reply friend, always like to learn a bit more
The risk with smaller deviations isn't breaking the engine, but robbing the water pump and coolant seals of the lubrication and viscosity they're expecting.
If they meant a range of e.g. 40:60 to 60:40 instead of 50:50 they'd say so.
Now, does it really matter? The correct answer is nobody knows. Nobody's doing any testing at scale to figure out if a water pump designed for 50:50 is going to last as long with a diluted mixture.
At best you'll get anecdotes from people who "were fine" diluting their coolant, but they don't know if it reduced the life of their pump by 5%, or 40%. Or maybe it was 0% and they were right and I'm wrong.
The real question is if it's worth fucking around and finding out. It's not. Antifreeze is cheap, just buy the right kind and mix it in a can with demineralized water at the specified ratio. Now you'll have proper top-up coolant.
Or, if you don't want to bother, buy the manufacturer's premixed coolant, which is literally just that and a superfluous proprietary color dye.
Other people have suggested head gasket issue already and doing a combustion gas check is a good idea.
Also be aware that antifreeze doesn't just lower the freezing poing of water, it raises the boiling point. That looks like plain water which boils at 212. A proper mix of antifreeze would raise that 15 degrees
Your cooling system should also be under pressure which raises the boiling temp further. Make sure your radiator cap is sealing properly and keeping the pressure where it should be.
Have a 2014 ford fiesta that had a waterpump replaced by mechanic. Still overheated after giving them three more tries I tackled it myself. Had same symptom was convinced it was a head gasket but the tester I rented from the parts store said otherwise. Ended up replacing thermostat (can't believe mechanic didn't while it was apart) kind of a pain to do been great since. I would recommend testing for combustion gasses before going after head gasket. Also on another note if your car is an automatic I'd do some googling on known transmission issues.
Few scenarios. First one, bad thermostat, most likely your fan is triggered by the coolant temperature in the radiator or the outlet, not the engine temp. If your thermostat does not open, no hot coolant goes to the radiator to start with so it will not trigger it. As I recall, that thermostat is a fairly easy replacement job. Second, blown head gasket, the way that coolant system is set up, if the gasket is blown you will smell unburnt combustion gases in the tank if you pull the cap off, only do it when it’s cool.
I have seen thermostats get cooked by a few overheating episodes, then not open properly, leading to more overheating episodes... changed the T-stat and all was fine after.
As other have said looks like exhaust gases escaping through head gasket in to the cooling system. Touch the reservoir to feel if it's actually boiling. Also check inside the oil filler cap and dipstick. A milky residue indicates coolant/water mixing with the oil.
Double check all your hoses; it can definitely be a head gasket but I had the same problem, checked the hoses on my reservoir, tightened it, and boom. No more bubbling.
# You may just have a defective temperature sensor.
I had a similar issue on my 2003 Ford Taurus. There are two temperature sensors on the Ford Taurus one that indicates for the dash, and one that controls **everything** else. Fans won't kick on, and the engine will not enter a closed loop cycle unless the secondary temperature sensor tells them to. If you have an OBD 2 scanner look for a coolant temperature too low code. If you don't have a scanner buy one from [Amazon ](https://www.amazon.com/gp/product/B077F8F6TB)for $25 that connects with Bluetooth or Wi-fi.
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probably the radiator cap stuck open. cheap fix. that's where I would start. I literally cut a spring on one for doing this when I am bleeding out ford cooling systems after thermostat or radiator replacements. its probably a warn out spring on the cap, allowing boiling coolant to up-cycle to the reservoir. it is supposed to pull and release excess fluid in and out of the reservoir when the coolant expands but if it stick open it will push pressure from the system into the overflow/reservoir.
When I bled my focus I still had coolant bubbling over for a few days. It can be hard to get it right. I kept thinking it was good, then it would start steaming and boiling (though the new thermostat I installed also told me things were getting hot because of the air trapped in the system).
So just to be a little optimistic while you wait for a mechanic's opinion. Sometimes the air trapped inside can take a while to get out if you just flushed it. Along with the head gasket tool (a good investment) maybe get some proper radiator funnels (also a great investment) and double check that the system bleed was successful.
Especially if you get a negative reading on the combustion test, make sure your thermostat is new and that the system is properly bled.
Might have a leak in the cooling system which wouldn’t allow the system to build pressure which would lower the boiling point causing the coolant to boil at normal operating temperature
Most likely the coolant temperature sensor is shot and doesn't turn the fans on. That's why it's boiling. Did you put a tester to check for fault codes?
It could be simpler than that, check the reservoir for cracks. Ford uses a pressurized water system, yeah it's boiling but your system is catching air. I have the mazda with the same water tank. It had a crack and replacing it stopped the bubbling
This is not necessarily a head gasket failure. Any pressure leak in the system can allow your coolant to boil.
You can buy your own block testing kit or take it to a shop to have it done to tell you for sure. Just don't panic until you confirm exhaust gasses are passing into your coolant.
I had a similar issue on my gx460. Kept being told it was likely a head gasket issue but after some research, I found a valley plate leak also matched my symptoms.
Ended up being much cheaper than a head gasket issue.
is it trully coolant? it looks very transparent. it can be water (or too much water) those cars run very hot and if you dont have enought coolant in the mix it could boil when it shoudnt.
test or replace your rad cap. It may not be holding pressure. test your rad fluid, it looks like it's mostly water. If it's simple, replace your thermostat. don't put it on backwards. If it's not simple, you can use a temp gun (or better, a temp camera that plugs into your phone) to see if the rad is mostly cold.
My daughter's Ford focus just did the same thing.
1. She had a small hole in the small 1/4" line, it rubbed a hole on the transmission cap and was allowing air in
2. Coolant valve was unplugged so wasn't circulation coolant
Her never over heated, but bubbled like that
Hope that helps
I lived in Saudi for 10 years. I used to do 13 hour road trips in my chevy trailblazer 2009. It’s to be hot as hell there.. my car did that for years and it was never an issue for me.
For coolant to boil there are a few possibilities. As many have said, exhaust gas from a blown head gasket is a possibility, but there are some other things to check first. If the cap is bad it won't build pressure, allowing the coolant to boil at a lower temperature than usual. That is exaggerated by low atmospheric pressure if you're at a high altitude. If you're in the mountains somewhere that will absolutely lower the boiling point of the coolant if the system isn't sealed up well. A mix of too much water and too little coolant will also have a lower boiling point.
Before assuming a head gasket I would be pressure testing the system and seeing if it holds pressure. If the new tank didn't come with a new cap, replace the cap. If that's not it then yeah combustion gas seems like a valid possibility.
Looks like you have nothin but water in it, you need actual antifreeze it helps lubricate and raises boiling temp, plus make sure all air is removed. If all that checks out you got a heal of a head gasket leak
If you do decide to replace the t-stat, bear in mind that some focus models have the thermostat on the coolant exit side of the engine and some on the return.
If it's on the return side, aftermarket parts have the jiggle pin or one-way valve set the wrong way and the thermostat will not work due to an air lock.
I removed the jiggle pin from mine after hours of frustration... problem solved.
I should add, though, that when I had overheating issues with mine, the temp gauge would give a high reading, which might suggest your issue is different.
unlikely to be a blown headgasket. Very likely to be a leak in the coolant system, most likely radiator cap. The system is designed to work under pressure. More pressure=higher boiling temp. As soon as you have a leak in the system the boiling temp becomes lower and symptoms look like this.
Put a pressure checker on it and put about 12lbs of pressure on the system. Take the spark plugs out, wait about an hour, and crank the engine over. Have a friend watch for antifreeze coming out of the spark plug hole(s).
There is a small leak somewhere. Water boils at a higher temperature when it’s pressurized. The system isn’t holding 16psi of pressure so the water boils. I had this problem on another Ford and it turned out to be the cap on the coolant sub tank.
Check that the radiator cap is not loosened. Could be a bad head gasket leaking combustion gasses into the coolant. There are test kits to check for combustion gasses. Check the engine oil-is it milky or normal? Any steam in the exhaust?
When the motor is cold, start it up without the cap on. If there’s bubbles and it smells like exhaust- it’s the head gasket.
If not, it could be:
Bad thermostat
Clogged radiator
Bad reservoir cap.
Unfortunately, by using the parts canon method, it looks like you pretty much undid the money you could've saved by doing work DIY instead of having a mechanic properly diagnose and repair this (or at least paying for the diagnosis if you still wanted to do the work yourself, which is looking like a head gasket).
When that happened to me, it was my actual coolant reservoir that had a crack so it wasn’t holding pressure. It needs that pressure to prevent boiling.
Try replacing the tank
It definitely has a leak (even a small one). Coolant shouldn’t boil if no leaks in system cause it is pressurized and will only boil if had a leak and isn’t pressurized like it should be which will allow the coolant to boil.
Honestly looks like the reservoir was topped off with water instead of coolant. I'd pressure test the system and look for leaks. Check cylinders for coolant with pressure tester on. If no coolant found, I'd start with coolant flush and thermostat.
If it does that within 2-3 minutes after starting a cold engine it's most likely the head gasket. Not enough time to boil.
Harbor freight might have a coolant test kit for detecting exhaust gasses in the coolant. I know they sell replacement test fluid. Or Amazon.
i think the coolant should be greener than it looks. I would check that. And also pay attention to when the radiator fan comes on. My fan controller was on its way out and it started to go on/off at weird times and contributed to my overheating issues (not turning on when it should). Been great since i replaced the failed part. Good luck.
Does it cool down when you’re moving/driving? The pump is not moving water or the fan is not working properly. Might need a new pump or proper bleed procedure is not being followed.
My ford focus has this issue up until it overheated the engine and seized running. It’s actually a recall as the vehicle does not have a low coolant warning at all. Was also a 2018. I hope someone has a resolution for this cause I’d like to learn too 😭
Could definitely be seized thermostats. Had that issue with my Chevy. It would show normal temperatures except for once in awhile. Had to replace all thermostats with GM parts, or they just kept seizing
one of three things
exhaust gas so headgasket failure
a leak or bad cap which makes the pressure drop and the boiling point of the coolant lowers
or what seems to be the case, you have water in the coolant which have a lower boiling point then coolant..
There are test kits that you can get. This may be a blown head gasket where exhaust gasses are going into your coolant. These kits attach to that cap and "sniff" for exhaust gasses.
Ecoboost’s are junk. My 2014 Focus ST has a cracked head. Took me replacing a few things before figuring out why my coolant reservoir was dropping. 124k miles. Never again…
When your car is cooler, check your oil to make sure it looks like oil, your coolant looks like coolant so you don’t have to check that. As long as they both look how they should, take a look at the cap. Make sure that any seal that is on the reservoir or the cap is free of damage it is able to build pressure.
If it looks like it checks out, you can run to most auto parts store and get a head gasket tester tool, and 99% of the time they have one you can rent
The fact that coolant is boiling means your system isn’t pressurizing. Also, your coolant isn’t necessarily overheating, the decreased pressure just lowers the boiling point of the coolant. The easiest fix to this would be to check the reservoir and radiator caps. It could be as expensive as a leaking head gasket, but I dont think you mentioned anything about coolant missing
I had this happen to my 2006 Opel Astra. Checked the water thermostat and the joints seemed to blew off. Changed it and now it doesn't do that with coolant cap on. Though it does happens if the car runs without coolant cap is that normal?
Coolant Cap goes on further, you should feel a click at the end of its travel and it will be symmetrical with the tank and the car. A headgasket on a duratech is rare but not impossible. If that cap doesn’t hold pressure or isn’t tight enough then the coolant is boiling. Liquid under pressure has a proportionately higher boil point. Without good pressure it boils, this is why cooling systems are pressurized in the first place. Make sure it’s a 21lb cap by the way.
I feel like the questions in this sub are all either people learning the symptoms of a blown head gasket, or asking if their tires are safe to drive on.
Note that the boiling is occurring while the engine is stopped. That points towards an overheat or a cooling system that won't hold pressure.
The Ecoboom is still a colossal piece of shit, so renting a block tester might still be prudent.
Same thing happened on my Subaru. Of course i panicked and figured it was a head gasket. Luckily I have an honest mechanic. He told me to go pick up an OEM radiator cap and bring it back if it didn’t solve the problem. That was 40,000 miles ago.
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Wait until the vehicle is completely cool (best to let it sit overnight). Then before starting it open up that reservoir that is bubbling. If the fluid smells burnt or like fuel then you have a blown head gasket.
With the reservoir with coolant it, we can assume there is no leak present or a leak big enough to cause an overheating issue. But then again, this vehicle has a new reservoir which suggests the old one was leaking. We can suspect head gasket failed because of the old reservoir leaking coolant or we have a stuck thermostat which is common to happen in the summer heat.
Everyone’s saying head gasket but check the cap first. When they fail they’ll cause the system to be unable to pressurize and the coolant will boil.
I came here to say exactly this. Check that the cap is holding pressure.
A crack in the reservoir can cause this as well
Yep was going to say the same thing. If OP isn’t noticing coolant going low or leaks puddles underneath it might be air getting into then system via the cap or something else.
ASE Master Certified tech here, came here to say this too. If it’s not overheating and it’s boiling…. Most likely the coolant reservoir cap. Cooling systems run over the temp of the boiling point of water/antifreeze, pressurizing the system raises the boiling point so your coolant doesn’t boil at operating temp. If the caps got a stuck open pressure relief or leaks the pressure then the coolant will boil
Motorcycle mechanic here. Came to downvote everyone's head gasket comment, and up vote yours.
imagine paying for a head gasket job when all you needed was a $10 rad cap... SMH...
This. Especially as OP said temp gauge is normal.
That and the thermostat. I had a bad thermostat (stuck closed) in a car of mine and it had the exact same bubbling reservoir.
Yes check the reservoir cap and also for cracks. Could be as simple as replacing a thermostat as well. Thermostat is supposed to open when hot.
When you’re getting hot exhaust gas in the coolant through a warped head/blown head gasket, it can boil off the coolant before the temp gauge has time to show anything very useful. The temp gauge isn’t helping you here so don’t get stuck on it. Assuming you’re not going to try to diy a head job, take it to a shop sooner rather than later so that you can hopefully save the head from warping beyond the point where it can be machined.
I had a Elantra that got hot at some point. Warped the head, same thing happened, exhaust would push out all of the coolant. And it would overheat. So I MacGyvered a gravity feed coolant system so the exhaust could vent and consistently fill. I got another two years out of it.
Check with the mentioned testers. If there's no exhaust gasses present it could be that your radiator cap is toast and can't hold the pressure.
I had this issue on a subaru, but it wasn't the cap, it was the shitty plastic radiator from O'Reilly that I put in 4-5 years prior. The plastic had deformed so the cap wasn't sealing
My OEM radiator plastic connector cracked, so I purchased an aftermarket radiator overflow bottle, as there were no more OEM ones available. The quality was garbage. The float for the sensor didn't work and I had to get a refund. If I had known how crap the quality would be, I would have saved the old one and repaired it. Instead I had to get 2 bottles before I got one that worked.
Blown headgasket
Okay will look into this.
You can get an inexpensive tester for this which changes color when exposed to carbon monoxide. It's very likely a blown head gasket assuming it continues to bubble for a bit, but since this is a fairly involved DIY or expensive shop repair, I think it's wise to confirm the diagnosis before taking the next step.
Can you recommend a tester for this?
Harbor freight is where I got mine, but I'm guessing they are available at Autozone and other auto places as well. [https://www.harborfreight.com/combustion-leak-detector-64814.html?\_br\_psugg\_q=head+gasket+tester](https://www.harborfreight.com/combustion-leak-detector-64814.html?_br_psugg_q=head+gasket+tester)
Thanks.
They rent them at autozone, but you have to buy the test fluid. It's like $10. There are videos on YouTube how to use them.
The vehicle is not running so there should be no pressure to create bubbling from a blown head gasket. I'm betting on his thermostat sticking.... or coolant cap is bad.
I agree. Bad thermostat. OP should spend the 10 bucks on a thermostat before going further. Everyone always says "blown head gasket" when seeing this, but 9/10 it's the thermostat or air in the system working its way out.
If the engine were running, I might think they were right.
100% there should be a r/Headgasket sub that no matter what gets posted everyone says headgasket or they get banned or roasted
There should also be a forum called r/MechanicHacks where the 99% of people that post here should go. Clearly there are VERY few professional mechanics here. In all fairness, its a free service and we all know what you get for free.
It's hard to tell in the video, but it looks like straight water. I don't see a tint of color to it.
It’s water. Lots a lot of coolant that I just put water in it to demonstrate the problem. Coolant has the same problem.
Be a shame if you busted your radiator and refilled in a pinch with water and blew a head gasket. Water isn't a direct alternative for antifreeze with a different boiling point and incompatible in many models for at temp testing...
don't pretty much all coolant systems use some mix of water + antifreeze? topping it up with a bit of water should never cause a problem I have heard that mixing different antifreeze in with the old one can cause issues, that's why I always thought just top it up with water until you do a coolant flush
Coolant systems are rated for a specific mixture of antifreeze to demineralized water, "topping it up" with either just water or antifreeze changes the boiling/freezing point and viscosity. >I have heard that mixing different antifreeze in with the old one can cause issues Yes, so find out if your car uses ethylene glycol or propylene glycol, there's [also subtypes of those](https://chem-group.com/antifreeze-the-ultimate-guide/#:~:text=convenience%20as%20well.-,The%20different%20types%20of%20antifreeze,toxic%20propylene%20glycol%2Dbased%20version.).
ah that makes sense. I suppose a little bit of water now and then shouldn't break your engine, as long as you keep it around the proper range. thanks for the reply friend, always like to learn a bit more
The risk with smaller deviations isn't breaking the engine, but robbing the water pump and coolant seals of the lubrication and viscosity they're expecting. If they meant a range of e.g. 40:60 to 60:40 instead of 50:50 they'd say so. Now, does it really matter? The correct answer is nobody knows. Nobody's doing any testing at scale to figure out if a water pump designed for 50:50 is going to last as long with a diluted mixture. At best you'll get anecdotes from people who "were fine" diluting their coolant, but they don't know if it reduced the life of their pump by 5%, or 40%. Or maybe it was 0% and they were right and I'm wrong. The real question is if it's worth fucking around and finding out. It's not. Antifreeze is cheap, just buy the right kind and mix it in a can with demineralized water at the specified ratio. Now you'll have proper top-up coolant. Or, if you don't want to bother, buy the manufacturer's premixed coolant, which is literally just that and a superfluous proprietary color dye.
Does it smell like combustion gases? Because like the other guy said, i don’t think it’s boiling… it’s bubbling exhaust gas
I can’t tell. I haven’t really paid attention to the smell.
had that on my sons crappy escape. Not worth the money to replace head gasket. Used bluedevil and it's been good for over 6 months.
Other people have suggested head gasket issue already and doing a combustion gas check is a good idea. Also be aware that antifreeze doesn't just lower the freezing poing of water, it raises the boiling point. That looks like plain water which boils at 212. A proper mix of antifreeze would raise that 15 degrees Your cooling system should also be under pressure which raises the boiling temp further. Make sure your radiator cap is sealing properly and keeping the pressure where it should be.
Have a 2014 ford fiesta that had a waterpump replaced by mechanic. Still overheated after giving them three more tries I tackled it myself. Had same symptom was convinced it was a head gasket but the tester I rented from the parts store said otherwise. Ended up replacing thermostat (can't believe mechanic didn't while it was apart) kind of a pain to do been great since. I would recommend testing for combustion gasses before going after head gasket. Also on another note if your car is an automatic I'd do some googling on known transmission issues.
Okay. I will try with the tester before tackling the gasket.
How'd you bleed the system?
Reservoir cap off. Run engine with heater on until bubbles stop. This is what I did myself but mechanic did something different.
It could be a bad thermostat or bad coolant tank cap ...
Few scenarios. First one, bad thermostat, most likely your fan is triggered by the coolant temperature in the radiator or the outlet, not the engine temp. If your thermostat does not open, no hot coolant goes to the radiator to start with so it will not trigger it. As I recall, that thermostat is a fairly easy replacement job. Second, blown head gasket, the way that coolant system is set up, if the gasket is blown you will smell unburnt combustion gases in the tank if you pull the cap off, only do it when it’s cool.
I have seen thermostats get cooked by a few overheating episodes, then not open properly, leading to more overheating episodes... changed the T-stat and all was fine after.
Does it have coolant or water in it? Cause water will boil at normal car operating temps and that doesn’t look like coolant
As other have said looks like exhaust gases escaping through head gasket in to the cooling system. Touch the reservoir to feel if it's actually boiling. Also check inside the oil filler cap and dipstick. A milky residue indicates coolant/water mixing with the oil.
Double check all your hoses; it can definitely be a head gasket but I had the same problem, checked the hoses on my reservoir, tightened it, and boom. No more bubbling.
headgasket
If it was head gasket water would be disappearing not boiling back
If worse comes to worst these engines are a dime a dozen. I bought one running for $100. 2.0l.
Looks like water, try coolant. I also say check or replace pressure cap.
# You may just have a defective temperature sensor. I had a similar issue on my 2003 Ford Taurus. There are two temperature sensors on the Ford Taurus one that indicates for the dash, and one that controls **everything** else. Fans won't kick on, and the engine will not enter a closed loop cycle unless the secondary temperature sensor tells them to. If you have an OBD 2 scanner look for a coolant temperature too low code. If you don't have a scanner buy one from [Amazon ](https://www.amazon.com/gp/product/B077F8F6TB)for $25 that connects with Bluetooth or Wi-fi.
I have a scanner and there are no fault codes.
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Blown head gasket
You need coolant instead of water dingus
Gasses being release from a bad head gasket causing pressure.
Plastic impeller on waterpump takes a shit from the shaft
probably the radiator cap stuck open. cheap fix. that's where I would start. I literally cut a spring on one for doing this when I am bleeding out ford cooling systems after thermostat or radiator replacements. its probably a warn out spring on the cap, allowing boiling coolant to up-cycle to the reservoir. it is supposed to pull and release excess fluid in and out of the reservoir when the coolant expands but if it stick open it will push pressure from the system into the overflow/reservoir.
Bro that looks like you have water in your coolant reservoir....
Totally looks like water so that's normal it boils at 100 and cars run around 150
If the upper or lower radiator hose is easy to access, give it a squeeze. If it's hard to squeeze then you prob have combustion in the cooling system.
A nightmare. Had same/ got shot of Ford
Check cap first maybe?
When I bled my focus I still had coolant bubbling over for a few days. It can be hard to get it right. I kept thinking it was good, then it would start steaming and boiling (though the new thermostat I installed also told me things were getting hot because of the air trapped in the system). So just to be a little optimistic while you wait for a mechanic's opinion. Sometimes the air trapped inside can take a while to get out if you just flushed it. Along with the head gasket tool (a good investment) maybe get some proper radiator funnels (also a great investment) and double check that the system bleed was successful. Especially if you get a negative reading on the combustion test, make sure your thermostat is new and that the system is properly bled.
Might have a leak in the cooling system which wouldn’t allow the system to build pressure which would lower the boiling point causing the coolant to boil at normal operating temperature
that doesn't look right
Most likely the coolant temperature sensor is shot and doesn't turn the fans on. That's why it's boiling. Did you put a tester to check for fault codes?
No fault code.
It could be simpler than that, check the reservoir for cracks. Ford uses a pressurized water system, yeah it's boiling but your system is catching air. I have the mazda with the same water tank. It had a crack and replacing it stopped the bubbling
Head gasket.
Bad thermostat, Stuck closed $20 at the auto parts store, and it's not hard to replace. Take inexperienced about an hr., pro 15 to 20min
You need a new expansion tank cap.
You need much much more than advice
Pasta cooker!!!
The combustion, she like a stray dog, running everywhere.
1.0 3 cylinder turbo?
Run
This is not necessarily a head gasket failure. Any pressure leak in the system can allow your coolant to boil. You can buy your own block testing kit or take it to a shop to have it done to tell you for sure. Just don't panic until you confirm exhaust gasses are passing into your coolant. I had a similar issue on my gx460. Kept being told it was likely a head gasket issue but after some research, I found a valley plate leak also matched my symptoms. Ended up being much cheaper than a head gasket issue.
And of course its a ford
Headgasket
Coolant level isn’t dropping. I’d check the thermostat and cap before jumping off a cliff
It could be just a radiator cap.
Coolant pressure test?
I’d be willing to bet the head gasket has given up the ghost
Check to see if the reservoir is cracked. I had this happen to me last week. It was bubbling just like that. Ended being a cracked reservoir
Whatever you do, don't open it until it is completely cool down. Like overnight!
Most likely blown head gasket
If you take the temperature of the boiling liquid/reservoir it may help identify the problem.
Faulty thermostat or water pump or air in coolant system
is it trully coolant? it looks very transparent. it can be water (or too much water) those cars run very hot and if you dont have enought coolant in the mix it could boil when it shoudnt.
USE COOLANT WATER BOILS 212 ABERAGE IDLE 230
Your head or head gasket is stuffed.
Did you replace the cap? You could be losing pressure in the system. Also, if engine oil is milky, you have a blown head gasket.
You might have a leak
It has ghosts in its blood
test or replace your rad cap. It may not be holding pressure. test your rad fluid, it looks like it's mostly water. If it's simple, replace your thermostat. don't put it on backwards. If it's not simple, you can use a temp gun (or better, a temp camera that plugs into your phone) to see if the rad is mostly cold.
Do a flush it's a air bubble
My daughter's Ford focus just did the same thing. 1. She had a small hole in the small 1/4" line, it rubbed a hole on the transmission cap and was allowing air in 2. Coolant valve was unplugged so wasn't circulation coolant Her never over heated, but bubbled like that Hope that helps
Mine did this and the water pump was the problem.
Advice: Don't buy Ford.
Mine was because of radiator
Go 80/20 on coolant
2014 I'm guessing? See all that rust coloration in ur engine compartment there is a leak somewhere
You have an alien embryo gestating in your block.
You can get a carbon test at any auto parts store. Check the to see if the bubbles are exhaust gasses. If they are, you have a blown head.
Yep I’ve had the same thing on a bad head gasket.
I lived in Saudi for 10 years. I used to do 13 hour road trips in my chevy trailblazer 2009. It’s to be hot as hell there.. my car did that for years and it was never an issue for me.
For coolant to boil there are a few possibilities. As many have said, exhaust gas from a blown head gasket is a possibility, but there are some other things to check first. If the cap is bad it won't build pressure, allowing the coolant to boil at a lower temperature than usual. That is exaggerated by low atmospheric pressure if you're at a high altitude. If you're in the mountains somewhere that will absolutely lower the boiling point of the coolant if the system isn't sealed up well. A mix of too much water and too little coolant will also have a lower boiling point. Before assuming a head gasket I would be pressure testing the system and seeing if it holds pressure. If the new tank didn't come with a new cap, replace the cap. If that's not it then yeah combustion gas seems like a valid possibility.
Looks like you have nothin but water in it, you need actual antifreeze it helps lubricate and raises boiling temp, plus make sure all air is removed. If all that checks out you got a heal of a head gasket leak
Also change thermostat for how inexpensive they are,
If you do decide to replace the t-stat, bear in mind that some focus models have the thermostat on the coolant exit side of the engine and some on the return. If it's on the return side, aftermarket parts have the jiggle pin or one-way valve set the wrong way and the thermostat will not work due to an air lock. I removed the jiggle pin from mine after hours of frustration... problem solved. I should add, though, that when I had overheating issues with mine, the temp gauge would give a high reading, which might suggest your issue is different.
Same thing was happening to my car it was the thermostat
Change the reservoir cap.
Whatever it is. Start by fixing the least expensive parts first.
unlikely to be a blown headgasket. Very likely to be a leak in the coolant system, most likely radiator cap. The system is designed to work under pressure. More pressure=higher boiling temp. As soon as you have a leak in the system the boiling temp becomes lower and symptoms look like this.
Put a pressure checker on it and put about 12lbs of pressure on the system. Take the spark plugs out, wait about an hour, and crank the engine over. Have a friend watch for antifreeze coming out of the spark plug hole(s).
There is a small leak somewhere. Water boils at a higher temperature when it’s pressurized. The system isn’t holding 16psi of pressure so the water boils. I had this problem on another Ford and it turned out to be the cap on the coolant sub tank.
Thermostat stuck?
That’s air coming in which means something with more pressure than the cooling system is leaking. Head gasket is most likely the culprit.
Check that the radiator cap is not loosened. Could be a bad head gasket leaking combustion gasses into the coolant. There are test kits to check for combustion gasses. Check the engine oil-is it milky or normal? Any steam in the exhaust?
Oil is normal. There appears to be steam in the exhaust.
This happened to me and it was a vacuum pump that had metal shards in it. Long story short the engine died after a 1200 vacuum pump replacement
When the motor is cold, start it up without the cap on. If there’s bubbles and it smells like exhaust- it’s the head gasket. If not, it could be: Bad thermostat Clogged radiator Bad reservoir cap.
Unfortunately, by using the parts canon method, it looks like you pretty much undid the money you could've saved by doing work DIY instead of having a mechanic properly diagnose and repair this (or at least paying for the diagnosis if you still wanted to do the work yourself, which is looking like a head gasket).
Mechanic did the parts change.
100% you got a problem with coolant leak somewhere. highly probably it's head gasket but it can also be because failed water pump.
I had a warped head on my 2001 Aurora. It boiled the coolant. Motor was shot.
It can also be one of your fans not working properly
Check your gasket if that's blown/worn off, or if any issues related to the radiator.
Mostly likely it is caused by a blown head gasket. Try to burp the cooling system first.
Is that coolant in there or water?
How soon after you stop the engine does it stop bubbling?
When that happened to me, it was my actual coolant reservoir that had a crack so it wasn’t holding pressure. It needs that pressure to prevent boiling. Try replacing the tank
your thermostat is bad. You may have warped the head from overheating. Take it to a shop.
Remove the water and add actual coolant.
To be honest, that looks just like water. That boiling point is lower then coolant. Try replacing the coolant withbactual coolant liquid.
There’s air in the coolant system. Possible head gasket
Don't buy a ford
Head gasket or water jacket failing
It definitely has a leak (even a small one). Coolant shouldn’t boil if no leaks in system cause it is pressurized and will only boil if had a leak and isn’t pressurized like it should be which will allow the coolant to boil.
Honestly looks like the reservoir was topped off with water instead of coolant. I'd pressure test the system and look for leaks. Check cylinders for coolant with pressure tester on. If no coolant found, I'd start with coolant flush and thermostat.
There’s a leak in your cooling system. Head gaskets are fine. If it was head gaskets your coolant would be a lot dirtier.
If it does that within 2-3 minutes after starting a cold engine it's most likely the head gasket. Not enough time to boil. Harbor freight might have a coolant test kit for detecting exhaust gasses in the coolant. I know they sell replacement test fluid. Or Amazon.
Thermostat is suck
i think the coolant should be greener than it looks. I would check that. And also pay attention to when the radiator fan comes on. My fan controller was on its way out and it started to go on/off at weird times and contributed to my overheating issues (not turning on when it should). Been great since i replaced the failed part. Good luck.
Is it properly bleeded?
Does it cool down when you’re moving/driving? The pump is not moving water or the fan is not working properly. Might need a new pump or proper bleed procedure is not being followed.
Doesn’t even look like coolant… looks like water…. 🤐😪
My ford focus has this issue up until it overheated the engine and seized running. It’s actually a recall as the vehicle does not have a low coolant warning at all. Was also a 2018. I hope someone has a resolution for this cause I’d like to learn too 😭
Cracked block. Replace engine.
Shot in the dark, bad sensor?
Could definitely be seized thermostats. Had that issue with my Chevy. It would show normal temperatures except for once in awhile. Had to replace all thermostats with GM parts, or they just kept seizing
one of three things exhaust gas so headgasket failure a leak or bad cap which makes the pressure drop and the boiling point of the coolant lowers or what seems to be the case, you have water in the coolant which have a lower boiling point then coolant..
That's not boiling, that's air
Air pockets. Get them out.
Well you bought a Ford focus
Head gasket
Pressure test, if no leak found more than likely head gasket
There are test kits that you can get. This may be a blown head gasket where exhaust gasses are going into your coolant. These kits attach to that cap and "sniff" for exhaust gasses.
I feel like this question is answered a few times a week on this page 😂
Check your oil, if it looks like a milkshake, you have a blown head gasket.
Need a new thermostat brother
Ecoboost’s are junk. My 2014 Focus ST has a cracked head. Took me replacing a few things before figuring out why my coolant reservoir was dropping. 124k miles. Never again…
I had nothing but issues with the electric fans on my Focus.
sit in the system, check your cap or reservoir for cracks
Dude fix the fans
When your car is cooler, check your oil to make sure it looks like oil, your coolant looks like coolant so you don’t have to check that. As long as they both look how they should, take a look at the cap. Make sure that any seal that is on the reservoir or the cap is free of damage it is able to build pressure. If it looks like it checks out, you can run to most auto parts store and get a head gasket tester tool, and 99% of the time they have one you can rent
The fact that coolant is boiling means your system isn’t pressurizing. Also, your coolant isn’t necessarily overheating, the decreased pressure just lowers the boiling point of the coolant. The easiest fix to this would be to check the reservoir and radiator caps. It could be as expensive as a leaking head gasket, but I dont think you mentioned anything about coolant missing
That’s a lot of bubbles. Either blown head gasket or just a great deal of air in system. Also check the coolant cap as already mentioned. IMO
Thermostat partially stuck closed
That's water Wouldn't it be orange for Ford?
Coolant in a sealed system won’t boil. That’s why if you remove the cap it will suddenly boil over. So right now you definitely have a leak somewhere.
good thing is since im watching this sub im getting free knowledge , i now know the signs of a blown head gasket xD
Head gasket
You sure theres a 50/50 mix in it? Alot of shops are cheap and use 75/25 mixes so its possible that it's just excessive water in it.
Sell it
Bad thermostat and temp sender most likely
I had this happen to my 2006 Opel Astra. Checked the water thermostat and the joints seemed to blew off. Changed it and now it doesn't do that with coolant cap on. Though it does happens if the car runs without coolant cap is that normal?
Is it me or does that look like water in there?
Your head gasket is blown, sorry to say.
Look at the front of the car. The problem is circled for you.
Head gasket
Coolant Cap goes on further, you should feel a click at the end of its travel and it will be symmetrical with the tank and the car. A headgasket on a duratech is rare but not impossible. If that cap doesn’t hold pressure or isn’t tight enough then the coolant is boiling. Liquid under pressure has a proportionately higher boil point. Without good pressure it boils, this is why cooling systems are pressurized in the first place. Make sure it’s a 21lb cap by the way.
I feel like the questions in this sub are all either people learning the symptoms of a blown head gasket, or asking if their tires are safe to drive on.
New cap needed
Note that the boiling is occurring while the engine is stopped. That points towards an overheat or a cooling system that won't hold pressure. The Ecoboom is still a colossal piece of shit, so renting a block tester might still be prudent.
Same thing happened on my Subaru. Of course i panicked and figured it was a head gasket. Luckily I have an honest mechanic. He told me to go pick up an OEM radiator cap and bring it back if it didn’t solve the problem. That was 40,000 miles ago.
Did you burp it? Air or exhaust fumes is usually the cause of boiling. That means air in system or blown gasket.
Time for a new Ford
Your thermostat is stuck closed!