coolant Overflow / Blown head gasket
 

This past weekend while driving my car a bit hard I noticed allot of coolant that had overflowed and gone all over the engine compartment and motor. Stopped the car and cleaned it up, checked for leaks around the water pump, all fittings, hoses, clamps - everything was ok. Started it back up and the water temp skyrocketed past 100 C. Shut'er down and filled it back up (4 pints). Let it run with the radiator cap off and everything cooled down. Seems I had just a bit of overflow...Any thoughts ? I have an overflow catchcan and I thought all the overflow would have gone into that instead of causing the massive mess that it did in the engine compartment :mad: :mad: :mad: :mad: :( :CRY:

That all sorted out - go back out...Halfway up the block and a massive PLOOM of white smoke coming out of the right sidepipe. Shut'er down IMMEDIATLY. Pushed it back home and trailered it to the shop. Blown head gasket on the # 8 cylinder head. Figured I might as well take the other side off, and sure enough it was getting ready to go in the exact same way the other side did. So - now what to do. Heads are going back to the builder for inspection and possible resurfacing on the one that blew. Block deck seems to be fine, however they used a graphite gasket on a 12:5.1 compression motor that I specifically said would be used for road racing. Is this normal ? Shouldn't they have used an O ring gasket ? Anything else I need to have looked at as a result of this before they put it back together ?? Thanks in advance FIXIT !!

BTW - The PSE 17" wheels were AMAZING...Although they do not have the classic vintage look, they turn the car into an absolute road devouring beast...I highly reccomend anyone who is planing to drive the Cobra hard put some on - they make an awesome difference.

Did the gasket burn or did it just get pushed up into the coolant passage near the intake side of the deck surface?

A half inch piece of the gasket blew out and we found it as soon as we pulled the intake off. It did not look burned, but there was a bit of heat scoring around area where is came off. Dean at House of Cobras said it looked ok and he thought the deck surface was fine but wanted to take the head apart and check it out...It looked as though the gasket just blew and got pushed out under the intake manifold.

agro1

I would use the a FelPro 1011-1 with the pre-flattened steel ring.

Scott

Check the head's deck surface, use the fel pro gaskets, and retorque the heads the next morning. You ain't runnung too lean (or not enough octane) and detonating the gaskets out of there are you?

FIXIT - No, the car is not running too lean and is not detonating...I am sure of that because I can only run 100 octane racing fuel (due to the compression) and am very mindful to listen for any detonation. I think it jsut plain blew...i caught it right away though and shut it down...

Anything else you think I need to look at ? Do you think the coolant overflow and subsequent lack thereof caused the gasket failure ? Also, why did the coolant overflow in the first place ?? The temp guage was at a good level...Thanks in advance.

agro1

Combustion pressurized the cooling system when the gasket blew and forced the coolant out.

Its a good thing it blew into the coolant jacket and not between cylinders. When they go between cylinders combustion can cut a channel through the block and head the same as if a cutting torch was used (don't ask how I know).

Scott

....Ahhhh haaaa...Forgot about that part. Backed'er up. Thanks Scott...

Good to know Scott - thanks again...

My best guess...
After the head was torqued down, you should let it sit overnight to relax after the compression. Then back the head bolts off and retorque. You will notice that the bolts turned a litle farther this time. If you don't do this, the head bolts will not be as tight as they should. Perhaps this was not done. You have a pretty high comp ratio, so you are in a greater risk of head gasket failure than most folks. There are alot of ways you can knock a head gasket out, I am just throwing out guesses for this instance. I did blow a head gasket on a stroker 351w once, the motor was running great, no signs of detonation, then the smoke screen out one sidepipe. Turned out that the motor wanted a little bit more fuel, never heard any detonation, but it's hard to hear with those sidepipes. Did you flood the motor than hydraulic a cylinder on fire up? just guesses here

agro1,

Take it back to CHP and let them handle it - they may refuse any and all warranty if you pull it apart any more.

What kind of a radiator cap are you using? Is it the right 'pressure' setting? Original Fords used about a 13lb cap, but if you are running a high volume water pump, it may be exceeding that pressure and blowing by the cap - a problem I had.

Brad