I somehow managed to see 240+ temps and didn't do any damage to the engine at all. I lost a belt and before I knew it the temp gauge was pretty much buried. Coolant was bubbling out of the overflow tank but that was it. Engine cooled down and that was it...back to normal.

I have head studs and a factory-sytle head gasket (nothing fancy) for whatever it's worth.

 

On most aftermarket aluminum heads with thick decks you will gall pistons before it gets hot enough to warp the heads.

 

a FRIEND turned my elelctric fan off while the car was idling and the temp got to 275 . it started boling over and i know the gasket is gone, do you thing i ****ed up the heads or something else?

 

oh yeah ,.... i also have 1/2 inch head studs

 

It is easy enough to check using a straight edge and feeler gages, You are allowed around .006 whole head(length wise). Just make sure you check it diagonally and straight accross.

 

and use a damn good machinest straight edge, not your kid brother's school ruler

 

Cheetah - hook the fan back up, crank the car up and see what it does. If you're losing coolant, or it's running funny, or if the temp runs back up quickly, you're gonna have to do some more diagnosis. But crank it up and drive it easy and see if there are any other symptoms. Perhaps it's just fine. If you're certain the gaskets blown already, when you pull the heads, you probably ought to let a reputable machine shop check them out for you. They can usually mill them to take care of any warpage that may have occurred. Oh yeah - send your 'friend' home while you do all this. I wouldn't allow him around the car anymore.

 

will a compression test on the cylinders show it being blown,i'm just assumming they're blown because it got up to 275. i don't really want to mill the heads because i have a blower, plus they've already been milled .030 from back when it was a motor car, and i had put dished pistons in it to bring the comp back down. if the gaskets are blown i'll have a machine shop check the heads out.

 

The 275 degree temps per se won't hurt your motor at all. The problem comes where localized hot spots cause steam pockets and a vapor layer to form, and the surrounding area loses the ability to transfer heat into the coolant. In that case, you have small areas that become much hotter than the surrounding 275 degrees, and this temperature differential is what encourages the warping. This situation is, IMO, a good argument for NPG coolant which will not boil or form steam pockets at these temperatures. It's good to about 370 degrees, even in an unpressurized system.

If your heads do turn out to be warped, you may only need to remove a few thousandths (often <.010) to true them. On a supercharged engine, you need all the gasket sealing you can get...you'd be better off to true the heads if needed, even if it meant reducing boost by a pound or two to remain compatible with the cylinder pressures/available octane balance.

Steve A.

 

amossm

i've heard about the npg stuff. do you think it's a given that the gaskets are blown. and going by what you've said, do you think they will be blown and warped? there is no water on the oil dipstick

 

cheetah - crank it up and see what happens. For a short run you won't hurt anything. If you've got warpage/leakage, you'll find out, then you have to tear down anyway. Cranking compression check may tell you about a problem if there is one. But I'd crank it up first.

 

yeah i'm gonna try that tomorrow. i'l post what i find out

 

A compression check will tell you if you're losing cylinder pressure, but not necessarily if you have a warpage that's causing a coolant leak. Drive the car a bit, keeping an eye out for white smoke in the exhaust or coolant in the oil. If you spy a problem, you're going to have to pull the heads to fix it anyway. At that point you can determine if there's any warpage. In that case check both the heads and the decks for flatness. If you get no adverse symptoms, your motor may be okay.

Keep a sharp eye out for trouble, but don't fix it 'til it's broke.

Steve A.