ZR-1 Maintenance Tips

General Maintenance

by Jim VanDorn

 

The most common call we receive by far is from a confused ZR1 owner. After years of reading everything from which thermostat to use, to what type of spark plug is best, the average owner is totally and completely confused...and for good reason. There are many varied opinions of what is best for our cars but that may depend greatly on how you use your ZR1.

 

After seven years plus, many ZR1's are finally accruing some mileage. We have had the opportunity to closely inspect many engines with a variety of types of use from normal street driving to severe "weekend" use (track time). Compiling this information we can now offer the ZR1 owner some observations. One rule we've adopted after hearing so many owners say the same thing is the "DIMWIT" or "Darn, if I didn't Mess With IT" rule. In other words, if you didn't have a problem, then what are your intentions in the first place? To date, the only company known to have a fleet of engineering ZR1's to test with was GM and it's affiliates.

 

Therefore, we must ask ourselves if their suggested procedures and parts recommendations should have a considerable amount of merit. Obviously they do, but on the other hand, there are no doubt areas for improvement. Although we will begin our segment discussing the routine and normal maintenance of the ZR1, there are many areas where an upgrade will be suggested.

 

Please understand that these are personal opinions and experiences and are not intended to conflict with service procedures outlined in the appropriate service manual.


  Articles

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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