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Corvette Valve Stem Seals - Beating The Morning Puff

Replacing Small-Block Valve Stem Seals

John Nelson Mar 1, 2004

A set of new, correctly installed valve-stem seals. Follow along, and we'll show you how this Vette became a non-smoker.

Imagine this scenario. You've scrimped and saved, and finally have enough dough to get the Corvette you've had your eyes on. Just for argument's sake, let's say that dream car is a cream-puff '92 automatic coupe with a mere 45,000 miles on the clock. It's almost perfect, the birds are singing, and all is well in the world-right up until some smart aleck notices the big puff of white smoke exiting the dream car's tailpipes when it's first started. Aarrgh! You don't know what's worse: The smoke or the insults. The only sure thing is that stopping one will stop the other. That means it's time to break out the tools and replace the car's valve-stem seals.


With the LT1 fuel rail covers and several hoses removed, the Allen-head valve-cover bolts can be removed.

In case you haven't guessed already, this tableau actually played itself out in the Team VETTE universe. So while we did heap copious amounts of ridicule upon the hapless late-C4 owner, we also followed along as he fixed the problem. The first order of business was diagnosis. How did we know he needed valve seals? We knew the car was burning oil, but from where? The big clue was that the white smoke only appeared after the car had sat for a while, and it was especially thick if the Vette had sat overnight. If oil was getting past the rings from below, any smoking would have been a full-time affair, and he'd be in for a big repair bill. But with leaky valve-stem seals, oil seeps into the combustion chamber from above and quickly burns off when the motor is started. Turn the engine off, and the cycle starts again. That morning puff gave us the answer.


You'll need to remove these bolts-which hold the fuel-injector wires in place-to move the harness away from the valve-cover lip.

How did the seals go bad? It may have happened because the car had only clocked 45,000 miles in its 10-plus years of existence. On the other hand, '92 LT1 Vettes--the first cars to use the Gen II small-block--were known to have some valvetrain problems. In this case, we could see that the valve covers had been removed at some point. The previous owner claimed no knowledge of this, but, in any case, the inner coil of the valve springs was broken, and the shards had damaged the outer surfaces of the seals. We're only going to touch on the valve-spring issue here-if your '92 LT1 comes up ill, make sure you get the correct replacement springs and seals from a Corvette-savvy parts man.

However it happened, the fix is within the abilities of all but the most mechanically inept. You'll need a few basic tools, one or two not-so-basic (but inexpensive) gadgets, and, most importantly, the ability to find Top Dead Center (TDC) on each of your Vette's eight cylinders. A good portion of patience is also in order. At the end of the day, however, you'll have an excuse to bolt-on a new set of snazzy valve covers, a Vette that doesn't smoke, and the smart-alecks who are finally silent.


Street & Performance
Mena, AR 71953



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