MRPVette

Just curious Who here has had a head gasket failure at some time on a C4 and at what mileage,did it over heat? what #cylinder ? mine went at 137K cylinder #7 and it never over heated which confused me at the time I thought it had to over heat to fail.

Joe C

I suspect my 90 had a head gasket issue sometime before I bought the car. the top of the engine was apart for some reason, so I'm guessing a head gasket. I bought the car with 36K on the clock. I am the third owner, and owner #2 only drove the car for about a year and 1200 miles. I'm thinking owner #2 sold the car due to massive oil leaks at the front and rear china walls, valve covers, and transmission pan. I attribute the leaks due to extremely poor skills of some numb-nut mechanic. when I repaired the oil leaks, I opted for full open, rear coolant passages on the intake manifold gaskets. I'm coming up on 3K miles since the manifold gasket change, and haven't noticed any temp issues, and that's driving all summer here in florida. BTW, happy to say the bottom of the engine/transmission is bone dry -

ch@0s

John A. Marker

I bought my 85 with 110,000 and installed AFR heads at about 140,000. Blew a head gasket at 223,000. And it was number 8. If you look at the3 gaskets, the coolant passage hole for 7 and 8 are VERY close to the cylinder wall for 7 & 8.

The other issue is that aluminum and cast iron expand and contract when heated and cooled at different rates which promotes failure. That is why GM went to the reverse flow running coolant thru the heads first with the LT1 generation.

Paul Workman

check your service manual.

As it happens, the ZR-1 guys have had head gasket failures after switching over to the Dexcool (orange stuff) coolant. (Marc Haibeck article on Dexcool vs. the older glycol (green) coolant.)

zr1fred

As John said above, if you have aluminum heads on an iron block, odds are you are going to experience head gasket failure eventually. The problem is heating and cooling cycles with the different metals expanding and contracting at different rates "scrubing" the head gaskets..generally at the end cylinders. LT-1s went to reverse cooling to help with that problem. Head gasket failure usually results in overheating, but overheating will definitely accelerate the condition.

l98tpi

I have had 2 failures and both were at the #7. The failures were on two different engines. Both failed just a little over 100K miles. Never overheated or anything. I could tell the engine started to miss a little at times and seem to lag a little. Pressure tested the coolant system both times and wa la, coolant in the #7 cylinder. It is common on AL head sbc's.

HlhnEast

When the head gasket on my '85 failed, the exhaust was leaking into the coolant jacket making the car overheat badly. The car had about 150K miles. I was really glad I have the old iron head gen 1 SBC or I would have been replacing the heads.

MRPVette

Looks like #7 cylinder is pretty common.

Cliff Harris

I started a thread on that very subject...

http://forums.corvetteforum.com/c4-t...umber-7-a.html

Andrewsvette

118k and drivers rear cyly forgot what number it was. No problems since

MRPVette

How many have you put on it since the head gasket?

MavsAK

I haven't....yet.
I know it's just a matter of time though.

Andrewsvette

About 10k it's not my daily anymore and I have to deal with this

gerardvg

Electrolysis and galvanic action is what happens with dissimilar metals, put an alluminum head on a cast iron block the head gets corroded.

You will have less head gasket issues with iron heads on an iron block, the inlet manifold gets corroded.
I got 170,000 miles on my old 85 engine. I upgraded to a forged 383 short block and i was surprised at how good the heads and shim head gaskets looked when i took the heads of to use on my 383, she could have gone another 100,000 miles.

Regular coolant changes with the corrosion inhibitors will give you the longest life.

Domestic hot water units will have a ten year life span, that is guaranteed by the sacrificial element. After ten years its has been eaten away and something else will start to corrode.

If you do not do regular coolant changes, the rate of corrosion gets worse.

samsonb

Anyone switch to yellow G-05 coolant? Wondering if that coolant would help or slow down the problem compared to green coolant?

scotth48

Mine went out at just over 100400 miles but it was I forgot to tighten a hose clamp after putting in a new opti on my '93. Because of the high temps I replaced engine with another. May rebuild the old engine someday. I di redo the heads and bought new gaskets for it but never installed, installing a low mileage from another "Ruby" instead. I did put my single sided pulley's and serpentine belt on and my opti that I had just put on even though the new engine only had just over 32000 miles, along with new water pump. Got spare stuff now!

armysnipe

Had a head (stock) gasket failure at around 65,000 miles. I purchased my car off a used car lot and when I got home the water pump started leaking in the garage. So, I replaced the water pump. In the quest for power I installed a procharger kit and then after a few test runs blew out the head gasket between #6 and #8 cylinder about midway. As far as I remember it didn't overheat, but a lot of sweet smelling steam came out the tailpipe. Im sure my failure was caused by boost..