1985 Corvette Common Issues

1985 Corvette Common Issues

The following list of common issues is intended for individual reference only, and may not reflect the specific issues of every 1985 Corvette.  This information comes from a variety of sources including the NHTSA Defects Reports pages.  While the intent of this page is to identify the common issues pertaining to the 1985 Corvette, it is not an all-inclusive list and should be used for reference only.

Mechanical Issues

Engine

The engine may shut off after it reaches normal operating temperature.  There are several possible items that could cause this.  They include:

1. Bad Oil Pressure Switch – If this switch fails/does not detect oil pressure, it will cause the engine to shut off.
2. A Bad Distributor Module – the module may overheat, causing it to fail.
3. Fuel Pump Relay – A bad relay will cause the pump motor in the fuel tank to fail, causing ignition failure.
4. The Throttle Position Sensor.
5. Mass Air Flow Sensor

For both the Mass Air Flow Sensor and the Throttle Position Sensor, it is important to monitor voltage across/to each of these sensors.  Improper voltage can adversely impact how these sensors operate and may cause engine ignition failure.

If the engine starts but will not continue running/idle, there are other items that may need to be considered as well.  In many instances, a rough idle/stalling engine may be caused by dirty/damaged fuel injectors.  Cleaning (and, if necessary, replacing) the fuel injectors may resolve this issue.   Carbon build up in the throttle body can also cause the same symptoms.  Cleaning the throttle body in conjunction with the injectors will eliminate many rough idle conditions.

If the engine will turn over but simply won’t run, the most common cause of this issue is a failed Computer/PROM.  Located under the dashboard, the PROM controls the ignition/drive functions of the engine.  Replacement PROMS are available from most aftermarket vendors.

Additionally, the L98 engines had problems maintaining idle due to the design and use of the IAC ( Idle Air Control Valve). To compensate for this issue, the idle speed needs to be adjusted to a minimum air rate of 500rpm.

The rear of the intake manifold is known to leak oil.

Transmission (Automatic)

Erratic shifting is known to be an issue in the automatic transmission.  A properly operating transmission should shift smoothly no matter what load is put on it.

Transmission (Manual)

The manual transmission is known to exhibit synchronizer problems.  The shift points should transition smoothly with no need to “double clutch” or “coach” the transmission into changing gears.

Rear Differential

The Dana Rear Axle/Differential is known to make a fair amount of noise.

Exterior Issues

Headlight Drive Motors

The drive motors that rotate the headlight assembly are known to fail.  The headlight motor transmissions use nylon gears which fail over time.

Interior Issues

The Dashboard

The dashboard is known to short-circuit, resulting in intermittent operation of the dashboard.  The result is a flashing dashboard – or – a dimly lit or a completely blacked out dashboard.  The main reasons for this issue are: poor electrical grounds, corrosion on the terminals, or burnt out lightbulbs.  To resolve this issue, one of three possible solutions exist.  These are:

1. One or, or as many as all four halogen 882 light bulbs may need to be replaced.
2. Clean the 882 light bulb sockets.
3. Check ground connections for dashboard to ensure proper grounding.

Driver & Passenger Seats

Because of the high side rails on the lower edge of the driver and passenger doors, getting out of the Corvette can be difficult.  As a result, the outside seat bolsters tend to fatigue, causing a number of issues – leather deterioration, tearing, structural fatigue of the bolster sub-assembly (padding).