The earlier LT5's commonly suffer from a several unique problems which can be resolved/avoided during the engine overhaul process. Many 90's have begun to blow smoke from the exhaust when used aggressively. This is usually a result of the fact that the exhaust valves were not originally fitted with seals. The cylinder heads can be machined to fit the seals eliminating this problem. Piston rings and cam chains on the 90-92 models have also been upgraded since the engine was originally manufactured.


Exhaust manifolds and catalytic converters were changed in '93 not specifically because of any horsepower issues, but because the catalytic converter was previously attached to the manifold making it unserviceable separately. With the '93 design, the converter can be replaced separately.

The earlier style converters have also suffered periodic failures. This can be catastrophic if the catalyst is ingested into the engine via back pressure. When this occurs, cylinder and piston damage usually results. Listen for any strange noises coming from your exhaust or any strange rotten egg smells. This can be a sign of impending cat failure. The older style catalytic/manifold units are no longer available, however, the newer manifold/converter units are available from GM for about $2,000 a set. Unfortunately, because of different flow characteristics, we do not recommend the replacement of just one converter assembly.

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