1986 Corvette Common Issues

1986 Corvette Common Issues

The following list of common issues is intended for individual reference only, and may not reflect the specific issues of every 1986 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 1986 Corvette, it is not an all-inclusive list and should be used for reference only.

Mechanical Issues

Engine

Engine is known to seize when water enters the engine air intake system. The air cleaner (located directly in the nose of the engine) allows water to flow into the cylinder chamber which causes engine lock up. Water can be pulled into the air intake system by the movement of air from the radiator fan when it is collected on the front air spoiler.

Engine stalls, surges and runs rough as the direct result of malfunctioning computer control module.

Fuel Injection

Fuel injectors are a common issue on early model C4 Corvettes. The most common failure of the injectors is an electrical short in the injector itself, which causes the entire injector bank to malfunction.
Fuel injection failure can be severe enough to prevent Corvette from starting.

Intake Manifolds

The intake manifolds are known to develop leaks. The lower end of the intake manifolds tend to leak both coolant and oil. The engine oil leaks most commonly occur on the flat side of the manifold while coolant tends to leak most heavily around the corners.

Transmission (Automatic)

The transmission overdrive engages erratically due to a faulty control assembly. This condition can prevent the transmission from shifting into higher gears.
Automatic transmissions exhibit difficult/hard shifting.

Brakes

Anti-lock braking system known to fail, causing brakes to lock up. The ABS system can also cause erratic pulsating in the braking system, even when brake pedal is fully depressed.

ABS relays and sensors are known to corrode due to moisture damage in a sealed compartment, causing loss of braking power.

The brake master cylinder are known to leak, resulting in loss of fluid which can cause brake fade/failure.
The front computer controlled power disc brakes are known to fail.

Electrical Issues

VATS (Vehicle Anti-Theft System)

General Motors started installing the VATS system in Corvettes in 1986. VATS (or Vehicle Anti-Theft System) utilizes a special ignition key that contains a resistor pellet. This special “pellet” utilizes one of 15 different resistances that, in connection with the key itself, serves to secure the vehicle. When current passes thru a key with the correct resistor pellet, it sends a signal to the ECM, and then closes the starter circuit. The ECM will not allow the fuel injection or starter systems to operate without a signal response from the VATS module. Since VATS is not connected to the alarm system, it is active even if if the car is left unlocked or the alarm system is defeated.

The main problem with the VATS system occurred primarily during the first three years of its production (1986-1989). The issue was with the material that the contacts of both the ignition key and ignition cylinder were made of. This material was prone to premature wear which resulted in poor contact, an incorrect resistance being seen by the decoder module, and consequently a “no-start” condition.

In July 1988, a GM Technical Service Bulletin (number 88-292) was issued. This TSB included the part number for a new ignition cylinder that has better contacts. Keys were also updated that were slightly longer and included better contacts. These corrections virtually eliminated VATS problems caused by internal connection issues.

Fuel Pump

Fuel pumps are known to generate excessive whining/noise. New design is known to fail prematurely. Noise is particularly notable during acceleration.

Neutral Safety Switch

The Neutral Safety Switch is known to malfunction, allowing the Corvette to be started while in reverse.

Anti-Theft System

Anti-theft system puts the ignition into a no-start condition.

Exterior Issues

Headlights

Headlight motors are known to fail, preventing headlights from engaging/disengaging.

Fiberglass Body/Seals

There are a number of fiberglass body panel components that are known to fail. These include faulty hood seals, leaky roof seals and deteriorating firewalls.

Door/Door Hinges

Both the driver and passenger doors are known to exhibit erratic vibration.

Interior Issues

Instrument Lights/Dashboard

The instrument panel are known to flicker on and off, especially while the car is idling.

The fuel gauge is known to fluctuate by as much as 1/4 of a tank, resulting in possible stall conditions from engine fuel starvation.

Shoulder Harness/Driver & Passenger Restraint System

Restraint system is known to fail during impact/crash conditions. The shoulder harness fails when the anchoring system breaks, thereby eliminating effectiveness of restraint system.

The seat belt retractors are known to lock-up which prevents the seat belts from being extendable/usable.

A second, similar condition causes the seat-belt/shoulder restraint system locks during vehicle operation, preventing the driver from being able to move properly while driving.

Seatbelts can not be buckled/unbuckled when driver seat is certain positions.

Door Locks & Latches

Automatic door locking system in car is known to fail, preventing access into/out of the car.

Other Issues

A number of cases have been reported that state that the 1986 Corvette has erratic acceleration issues. In several instances, erratic acceleration is unexplained. It has resulted in loss of control and vehicle damage.