I purchased my 1985 C4 Corvette in January 2015 from a gentleman who lived about an hour north of me. I had been looking for one for a while after my 18-year-old son suggested we get one to work on together. We checked out several that were described as clean or nice that was anything but. There are a lot of people out there that think their Corvette is worth a lot more than it is.
One day, my son saw a Corvette for sale on Craigslist. The gold color was not my first choice, but the pictures looked good and it was pretty reasonably priced. We went to look at it and take a drive and the car was pretty much as described. We went back and forth on price a few times and finally settled on $4,700. The Corvette was ours. We went to pick it up and I let my 18-year-old son drive it home with his 15-year-old brother. After the nearly 1 hour drive, we pulled into the driveway and the first thing my son said was, the check engine light came on.
The top 5 1985 Corvette problems
Turns out my check engine code was error 32-Exhaust Gas Recirculation Circuit. I got lucky and it was a disconnected vacuum hose that I found rather quickly. Hooked it up and bingo, no more Check Engine message. Besides the check engine light coming on, which can occur on all vehicles I’ve had some typical C4 Corvette problems. One of the main reasons I bought this car was to work on it myself. These are the top 5 biggest issues I have come across since owning the car and have since repaired myself:
- Oil leaks – The first issue I found was a pretty decent leak leaving a stain on my garage floor.
- Leak at China wall. This is leak on the back of the engine near the firewall on the drivers side. To fix this you have to remove the intake manifold which is not a hard job but it does take some time if you haven’t done it before. Definitely a common 1985 problem
- Valve cover gasket leaking – Leaks coming from old or failing value cover gaskets
- Intake manifold leaks – When trying to fix the China wall leak I noticed some coolant was leaking into my cylinders. I had planned to replace the intake gaskets anyway, since I had it removed. Coolant on the top of the intake manifold is also a sign of this leak.
- Leak at China wall. This is leak on the back of the engine near the firewall on the drivers side. To fix this you have to remove the intake manifold which is not a hard job but it does take some time if you haven’t done it before. Definitely a common 1985 problem
- Clutch master and slave failure – Clutch pedal went all the way to the floor. I think it was the slave cylinder going out but I went ahead and replaced the master and line between the two. Getting the air out of the clutch system is a big pain in the keester after replacing everything and refilling the fluid. Also be aware, there were 2 manual transmission choices for the C4 Corvette.
- Bad door and window seals – This can happen to any 30+ year old car but its even worse on a Corvette especially since it has the removable top. A lot of times you can tell about leaks by the carpet. Leaks on the hatch will show up in the cargo area and leaks around the door show up on the floor.
- Headlight motors going out – My passenger side headlight stopped opening. Typically, the plastic gearing goes out and needs to be replaced. This was not the case with mine, it just needed to be cleaned and reset. I had ordered a refurbished one but it didn’t work either. New ones are available but will set you back a few hundred dollars.
- Dashboard problems – Affectionally know as the Atari dash board, the 1984-1989 dashboards can be problamatic. Fixing them yourself can be difficult and new or refurbished ones can be expensive.
Other possible L98 Corvette C4 Problems
These problems are more related to early C4 Corvettes 1984-1990 with L98 engines. I have not personally had these issues but they do come up.
- Blown head gaskets – The 1985 Corvette and the early 1986 Corvettes had iron heads to go along with the iron block. Blown head gaskets are not as prevalent in these years as 1986 and later when Chevy went to the aluminum heads.
- Transmission problems
- Clutch replacement
- Overdrive on the 4+3 manual not working properly
- Fluid leaks from both transmissions
- Rear differential – leaks and failure, a whine noise while driving is an indication
- Overheating
- Vehicle Anti Theft System (VATS) – Started with the 1986 C4 Corvette. Problems with this can cause starting issues. Many people use bypass methods to remedy the problem.
- Fuel injector issues – Clogged or just worn out. The cold start injector is a known issue as well.
The other non L98 C4 Corvettes
My personal knowledge is currently about the L98 Corvettes. I don’t have personal experience with the other C4 engines. So I’ve never had a LT1, LT4 or an LT5 ZR1. But these are some of the typical Corvette issues known to happen.
- Optispark system failure – Started with the 1993 Corvette
- Oil leaks
- Head gasket
- PCV valve failure
- Overheating
In terms of non engine issues, they majority of the car was the same thru the C4 Corvette years. One should expect the same type issues here. The dashboard did change for the 1990 year and didn’t have as many issues as the early clusters.
Other things to consider
Problems with all cars and typical wear and tear
- When I first purchased my Corvette I noticed the tires were well over 10 years old. Tires over 10 years old should be replaced no matter how much tread is still available. Finding the correct size 16 in tires for the original wheels. 255/50/16 are getting harder and harder to find. That is why more individuals are moving to larger sizes.
- The battery will need to be replaced a little more frequently if you don’t drive your corvette on a regular basis. The process to replace the battery takes a little more time than a typical car.
- Seat issues – torn or worn out
- Ignition system – spark plugs and wires
Conclusion
While any 30+ year old car has problems, I hope this post answers some questions about typical problems on the 1985 C4 Corvette as well as other issues that can occur with C4 Corvettes. This is not meant to be an all-inclusive list, just items that I have come across and am aware of.
The problems with my 1985 C4 occurred before I started this website. Future posts will include directions and links to help individuals interested in doing work for themselves.
Have a comment or another problem that I missed? Please leave a comment about it or anything else on this post.