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.

There are several concerns with regards to the AC system on our cars. If your AC is cold, then leave it alone. If it fails to cool to your expectation, then servicing might be in order. A certified AC technician will reclaim any remaining freon from the system, then replace both shrader valves (under the caps-look like bicycle valve stems) and either clean or replace the orifice tube which is located within the low pressure line. After a leak test, the system can be refilled to proper specification.

If your system suddenly gets warm, makes noise or emits smoke, then a more dramatic problem has occurred. Compressor failures with the Nipendenso compressor are quite common. The compressor comes separate from the clutch so both must be ordered and are strongly suggested to be replaced as a set. The plenum must be removed for this procedure..

The Corvette AC system is engineered using several types of metals. Unfortunately, some of these metals don't quite like each other all that well. An example is the AC lines which are made of an aluminum alloy but attached with a steel nut to an aluminum thread. In many cases, these lines become frozen to the component (drier or evaporator) causing them to be damaged during the removal attempt.


Don't blame your local technician when this occurs, this is an existing engineering problem. All fittings should be treated with either a teflon tape or anti-sieze equivalent when reinstalled. Although the 90-93 ZR1's were designed using the no longer manufactured R12 type freon, these systems can be converted to the newer R134a freon using basically stock components after a thorough cleaning and resealing operation is performed. Obviously, the best time to consider the changeover is when the system requires a major repair such as a compressor change.

Note: Always have the accumulator/drier replaced when changing the compressor.

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