Tvette99

1990 corvette
Hey guys I have been shopping for my 2nd corvette for awhile now. I had originally decided to get a 90 or 91 to avoid the optispark issues. However after reading this thread I just dont know lol. Pre 91 ive read that they suffer from intake manifold leaks causing head gasket failure typically in cylinder #7 I now know after reading this article what causes it and how the lt1 fixes the problem with reverse cooling. I have several questions, apparently there was a service bulletin in 1991 that supposedly fixed this issue what exactly was done on the 91 to alleviate this problem? My other questions basically what can be done to prevent this or help alleviate the problem aside from a cooleropening t stat and the dual aluminum radiatorare there any other.tricks to help ? I ask this because typically I have the option to buy a 90 over a 91 quite often!! Also how common is the issue with the last couple years of L98 engines ... Should I just forget them and get a 95 or 96 with a vented opti???? Im glad I found this thread but now im second guessing what i want to do !! Also how do you know if the 95 vette has a vented opti for future refeerence is it based on vin number ? Ive also read that chevy fixed this intake/head gasket issue in the 91 model however I have been unable to find and definite info on this matter. I basically want to know if no buy a 90 or 91 is it just inevitable that at some point I will have to replace the intake and head gaskets ???

Thanks in advance you guys

bjankuski

There are no major issue with head gaskets on a 1990 or 1991, sometimes gaskets fail but to say it is inevitable is an overstatement. The L98 is a SBC and they have built millions of them over the years and they are very reliable.

Polo Vert

It's been said here many times and the best advice is to buy the nicest and best kept car you can afford. They all have their own little quirks. My 94 has been virtually trouble free in the 6 years I've owned it. It's on the original non-vented opti and while I could listen to all the horror stories around here about failures I'll worry about it when it gives me reason to. In the meantime I'll take good care of it and enjoy it. I wouldn't pass up a nice 92-96 just because it had an opti. I'm thrilled to death with my LT1.

cv67

Another vote for finding the nicest well maintained one you can & wait for one that calls your name. There are still tons of very nice ones with long time owners out there.

vader86

I would not give this a 2nd thought. Head gaskets do fail but are not a big problem. Intake manifold leaks are not a big problem. I've never had one blow in the 86 or 88.

With improper maintenance, sure, and it could happen to any SBC. Can happen to the LT1 engines too. Just don't let any aluminum headed engine get over 250F (coolant) very long and it should not be something you worry about for well beyond 100K miles, 200K even if youre taking good care of it. If you do the required maintenance you need not make cooling modifications to keep it well below that danger zone.

Buy the car you like and learn the required maintenance.

Churchkey

90 right side radiator fan is controlled by AC high side pressure simply connect the fan relay ground wires together both fans will run when AC is in use or 228* coolant temp when the AC is not in use. In traffic I turn the AC on to trigger the fans it will run on the T-stat temp.

90 air bag is 90 only no repair parts are available.

Between my long gone 89 & my 90 +200K miles no head or intake gasket issues.