bubbling coolant

[Skybox2288]

Coolant boils/bubbles after hard driving/ thermostat reads that its not overheating though. also, i have to refill the antifreeze/coolant every couple of days. any idea what this could mean?? thank you:thankyou:

 

[frosho]

Is it boiling out of the overflow tank? Sounds like it's probably a bad radiator cap.

 

[gmorrell]

^^^ What he said.
Best case:
If it boils after shutdown, it's very probably a bad radiator cap. If the cooling system isn't up to pressure, the boiling point is lower than it should be, but it will usually be OK as long as there's air moving through the radiator. Once you shutdown, the latent heat in the block and heads boils the coolant, and it bubbles into the recovery reservoir, usually overfilling it, which is why you're adding coolant occasionally. Get a new radiator cap and inspect the upper and lower sealing surfaces in the radiator neck, check for debris, cracks or gouges.

Worst case:
Blown head gasket. Find a high cliff, do your best Thelma and Louise end of movie reenactment.

 

[Skybox2288]

ok, and when it boils it starts to burn coolant, and you can see/smell the smoke come up from the coolant tank. and the radiator cap is the one that says 'do not remove' in the front?

 

[RAYJAY]

does the over flow tank smell like exhaust fumes ??? do a hydro carbon test on the coolant,

sounds like a head gasket not common but they do happen


my 1993 atx did it

 

[gmorrell]

ok, and when it boils it starts to burn coolant, and you can see/smell the smoke come up from the coolant tank. and the radiator cap is the one that says 'do not remove' in the front?

Yep, "Do not remove when hot", heed this or you may get steam burns. When the engine is completely cool, you can remove the radiator cap and inspect the cap gaskets and the surfaces they seal to in the radiator neck. Take the cap to an auto parts store, preferably by driving another car, and get a new one.

 

[gmail]

i vote do a leak down test on the rad.. they are more common to get a pin hole in them then anything else... at least in my experience and if it dont build proper pressure it will boil... a way to see that is use a rag and when hot take the cap part way off see if there is a bunch of pressure shooting steam and coolant out... be careful and do not remove the cap all the way just part way to see if there is pressure...

could also be the cap as stated above

 

[kevinspann]

Yep, "Do not remove when hot", heed this or you may get steam burns. When the engine is completely cool, you can remove the radiator cap and inspect the cap gaskets and the surfaces they seal to in the radiator neck. Take the cap to an auto parts store, preferably by driving another car, and get a new one.

Oddly enough, the Motorcraft cap on my car just says "DO NOT REMOVE", he must have a similar one.



But really, don't remove it when the coolant is hot, especially if it's boiling in there.