Can Boiling Coolant make a Head Gasket Blow

[HangerHarley]

After Shut Down?

My car stays right around 200 Degrees operating temp, if the Temp gauge is to be believed. It gets Hotter when the Engine is off, or "Hot Soak." Sometimes i turn it on and it will be 230 Degrees..

I wonder if this Boiling Coolant ( have mostly Water in there) after Shut Down can pop a Head Gasket.

So far, it has held up. It does not "Overheat"" the issue is the boiling point of Water, and the Expansion Tank has a leak, so it boils there.

 

[The_Jeff]

No, because the head gasket is part of the pressure-holding capability. It doesn't care what it's holding, it can handle 15 PSI in the water jacket.

You should however fix the pressure leak or start running 50/50, either alone will handle the 230'F hot soak.

 

[OilNerd]

Most coolants mixed at 50% concentration boil at around 265°F.

 

[rslifkin]

The 265* boiling point for a 50/50 coolant/water mix is usually rated with a 15psi pressure cap. At ambient pressure, it will be less.

 

[Carbon]

Originally Posted By: HangerHarley

I wonder if this Boiling Coolant ( have mostly Water in there) after Shut Down can pop a Head Gasket.


That 15 PSI or so is far below the hundreds of PSI that the head gasket faces during fuel ignition.

 

[PandaBear]

If it is only water, yes it can boil and the pressure build up will be enough to cause problem, usually it will blow through the radiator cap first (whatever PSI it is for) and only if you have some problem with the gasket will it blow through the gasket first.

I don't think 230 is enough to warp the head or the block, but if you were running water in there, it could have causes air bubble and the temperature locally could be way higher than what your sensor / thermometer is reading.

Use something designed for the cooling system, and that's for sure not "mostly water".

 

[The_Jeff]

Originally Posted By: Carbon
Originally Posted By: HangerHarley

I wonder if this Boiling Coolant ( have mostly Water in there) after Shut Down can pop a Head Gasket.


That 15 PSI or so is far below the hundreds of PSI that the head gasket faces during fuel ignition.


Yeah but that's in a fire ring.

Though the oil passages are very similar to the water ones and they could see higher pressure too.

Another thing to be concerned about though: cavitation. When you're real close to the boiling point it eats away at the impeller of your water pump and some other areas. The best way I can explain it to myself is the localized vacuum perhaps behind an impeller, sucking water in to get pumped, acts like thin Denver air: stuff boils easier. Cavitation gets blamed for wrecking water pumps and similar stuff.

 

[ffhdriver]

Water at sea level and a 15 PSI cap will boil at about 250 degrees.