Here's an interesting one......Went to start the 'Vette (1990 L98 coupe stock engine) one night last week. When I hit the starter, the engine locked up, would not turn over. Horrible metal-to-metal CLUNK!!! After trying it two, three times with same result, decided the starter had frozen. Took the starter off, bench tested it and it worked fine. OK, he said, it must have just locked up temporarily and now it is free. So I reinstalled the starter and the engine turned over and ran. RIGHT he said! [IMG][/IMG]

While I was under the car I decided to change the oil. Took the drain plug out and a quart of real pretty green anti-freeze came out first, followed by 4 quarts of oil, and then about 2 pints of brown milkshake! Could be a problem here.

Making a long story short, what happened was that the left side head gasket blew, anti-freeze filled the combustion chamber and locked the engine from turning over until the compression leaked down. Luckily I decided to change oil and caught the problem in time before any damage was done.

Moral: Due to the lousy design of the aluminum head, the water jacket is so close to the sealing ring on the head gasket, that when the head starts to corrode, you lose the seal and water pours into the combustion chamber. Right now I'm in need of some advice.

Do I have someone weld up the water jackets to give me some extra surface area for a better seal (cost=$200 for both heads + reconditioning costs TOTAL of $350) OR just buy new/used heads (Ebay $400-700)?

Need opimions from you experts! Thanks.

 

A good machine shop can tell you if they can repair your heads. Whatever you do about your heads, when you install them, use Fel-Pro head gaskets, they last a long time and are teflon coated. The factory gaskets never lasted me more than 1 1/2 years.

 

You may want to talk to a professional engine builder about whether there is any damage likely to the bearings. I have read that antifreeze in the oil destroys the bearings pretty quickly. You don't want to do all the head work then have to take apart the engine again.

As for the issue of the aluminum heads and corosion. I suggest when you refill the coolant system, use 50/50 mix of antifreeze and distilled water instead of tap water. This is pure water without any minerals and totally neutral acid-wise.

Another important point is using the correct head gaskets, head bolts and torque procedures. The factory head bolts are Torque To Yield (TTY) and should not be reused. Also, there is a factory procedure to tighten the head bolts using a torque angle meter, available for $10 from Autozone. Basically, this stretches the bolts to a very specific length and does not rely on the old method of torque wrench.

If I were you, I would consult a local engine builder familiar with your problem to determine what caused the failure. Do not assume its the heads themselves.

 

I have the same year Vette and the same exact thing happened to me about 2 1/2 months ago. I posted it too. With 241K miles on my coupe I decided to have a zz4 installed. I could have gone the rebuild route but I figured the price for new vs. rebuild was only about $1500. The car went to Corvette Mike's in Anaheim on last Monday and they started workin on it on Tuesday. I can't wait to get it back!! :cool:

 

It's also possible to bend a rod just from the starter cranking a motor against a "hydraulic lock" from fluid in the cylinder. If you're thinking about going back together with your short block, compare the piston height at TDC of the "bad" cylinder with a good one. If a rod is bent, the difference will be obvious.