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Chevrolet Corvette C4 in the service station: US sports car in need of care

Chevrolet Corvette C4 in the service station
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' The Corvette C4 built a bridge to modernity ', describes Corvette specialist Walter Renz from Jettingen near Herrenberg Version of the legendary Chevrolet sports car built from 1984 to 1996. In fact, on the one hand there are grease nipples on the C4, on the other hand, electronic components increasingly found their way into the world as production progressed. The further developments made in many areas of this Corvette benefited its sporting virtues, but not necessarily in terms of ease of maintenance. Workshops that are not familiar with the Corvette C4 quickly lose track of things.

If you repair cheaply, you have to do it twice

In this service station, we focus on the Corvette C4 built from 1985 with L-98 engine and Bosch injection, but for reasons of space, some of the work described, such as the brakes, had to draw the line at 1987. 'Basically, the Corvette C4 is a reliable car and not a craft shop,' emphasizes Peter Wolfensberger from the Corvette Factory in Sirnach, Switzerland. The problems start when the buyer buys a poorly maintained vehicle or repairs have been carried out according to the motto 'as cheap as possible'.

As a concise example, Walter Renz gives the six light bulbs mounted in the dashboard of the Corvette C4 which at GM cost almost 40 euros each. If one breaks, apparently identical, much cheaper bulbs are often used. 'But then they have a different power consumption or heat generation, and after a while the circuit board is defective,' says Renz. The result: total failure of the digital displays and a repair of around 2,500 euros.

Sometimes, however, the poor accessibility simply leads to increased repair costs. A banal spark plug change on the Corvette C4 versions with the aluminum cylinder heads used from 1986 onwards easily costs over 200 euros. 'Six spark plugs can be changed in 20 minutes, the fitter needs almost an hour for the remaining two,' says Renz.

Heat-stressed ignition cables

Another example is the injection nozzles of the V eight-cylinder. They are only changed if absolutely necessary, because that takes six hours of work. Replacing the fuel filter can also depend onCorvette C4 model degenerates into a time-consuming and correspondingly costly fiddling.

As already mentioned, the C4 is not a capricious car, but the likelihood of defects increases with age. This can affect, for example, the heat-stressed ignition cables. If new ones are installed, this should be done carefully and using the brackets provided, otherwise the exhaust heat will kill them again.

Good equipped workshop is important

Other components of the Corvette C4 that may be due are the air flow meter of the injection system or the engine control unit (ECM). The corresponding test device is of course helpful when checking the drive, but not every workshop has it, which is why some parts are often replaced with good luck. More costly defects that can occur over time, for example, affect the dual mass flywheel. This manifests itself in the form of a metallic clacking, which disappears again at a higher speed, especially when idling. The necessary repairs cost about 2,000 euros.

However, GM can no longer supply flywheels. Either the workshop knows another source of spare parts or they would have to convert to a normal flywheel plus clutch. But then the transmission of the Corvette C4 is stressed by strong vibrations, which it does not benefit in the long run. Loosely around 1,000 euros are due if water loss occurs at the seal between the cylinder head and intake manifold. The reason for this high financial commitment is in turn due to the high workload. Eight hours and more can be required for this work, and the flange surfaces may also have to be planned.

Engine overhaul for the Corvette C4 from 6,000 euros

And how expensive is an engine overhaul? If you value matching numbers, you shouldn't opt ​​for a cheap GM Goodwrench engine, which is currently only available from model year 1992 in the Corvette specification for the C4, but should have the built-in machine revised. This costs from 6,000 euros and up, depending on the effort involved or the necessary parts.

Replacing the bushings and ball joints

We come to the chassis of the Corvette C4, whose rubber bushings are of course also aging. 'Replacing them is not expensive in terms of material, but because of the high workload,' emphasizes Peter Wolfensberger. Often the somewhat tighter PU bushings are used.

As part of this repair, it remains to be considered whether the owner can also have the supporting joints on the front axle replaced, which incidentally requires a press. Because the supporting joints also suffer from wear. If you have them replaced separately, the dismantling work required to replace the rubbers is no longer necessaryagain - you pay it twice. The front axle is basically quite robust. Wear is also kept within limits if the three grease nipples per side are regularly supplied with grease.

From 1988 with two-piston floating caliper brake

On the subject of brakes, it should be mentioned that General Motors prescribes the use of DOT 3 brake fluid. The prices given in the table for a brake pad change apply to the Corvette up to model year 1987, after which a two-piston floating caliper brake was used. The pad change is then more expensive and costs around 200 euros. Up to model year 1987, the Corvette C4 also had separate brake shoes for the handbrake, so the handbrake pad change was taken into account in the table.

Should a wheel bearing fail, the entire hub will be replaced because the bearings are not individually there. This makes the replacement part expensive, but installation is quicker. The supply of spare parts for the Corvette C4 is largely unproblematic. However, there are often different qualities to choose from. Some components from the accessories that are cheaper than GM parts turn out to be quite useful.

You should keep your hands off the extremely cheap replacement that was not taken into account when calculating the service table. In such cases it is best to rely on the experience of the workshop. In any case, it is absurd to think that American cars with V8 engines require next to no maintenance. That doesn't apply to the Corvette C4.


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