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This might sound completely obvious, but I’ve never owned an old v8 car none the less a corvette. Just bought a 1986 c4 auto with 78k miles on it. I’m changing all the fluids, but should I skip doing the transmission fluid? Don’t want to ruin anything. If it’s recommended to do, which fluid do I purchase and from what store?
Congrats on your C4- you will have a blast with this car.
You need to "Baseline" this car. Essentially inspect all systems, replace fluids and test/check all functions. This way you will know what you have for a starting point. Sounds like a lot, but it should take just a few hours.
Some suggestions...
1) Order a FSM (field service manual) as your first purchase. This will save your a** often and save you thousands.
2) Clean your radiator/AC condenser by cleaning (remove your shroud) the leaves, junk etc. Your car will run cooler
3) install an emergency hood release cables
4) learn the "Paper clip" method for reading your car codes
5) Give your engine a proper tune up- plugs, wires, rotor, cap and advance for ignition as far as it will go. 8-12 is "in zone" for timing
6) take your car to AutoZone and have them test (this is a free service) the battery, alternator and starter. Make sure these are in spec
7) Change your fuel filter and run a can of (Yes, haters jump in) SeaFoam through your system
Start here and you will have a very squared away car.
Good luck!
Last edited by billschroeder5842; Jul 4, 2020 at 01:31 PM.
Thanks bud. So I should stay away from dex 6? Because the only place I can get dex 3 is online where I live
Yes. Dexron 3 is the only one. I think Walmart has Valvoline for like $14/gal. I would order 2, and that should cover it. Don't forget the filter. Stay away from synthetics, especially with this year.
One of the things you really want to check is if your throttle body and plenum are choked with crap. When I got my 85 I took them off and found that the entirety of the EGR return was choked with carbon. Took me a long time to get it all out but it's essential to the engine running right and isn't that scary a job. I took off the runners to clean them too, but didn't go so far as taking the intake off.
They need to be cleaned around this milage so it's probably a job you want to do. This will start you out if you need to clean them
Also worth mentioning that you require a high zinc oil in that engine. The 86 still has a flat tappet cam and requires zinc for lubrication. Oil companies have been progressively removing zinc from oil because modern engines don’t require the same levels of zinc.
It's recommended to just drain as much ATF as comes out the bottom, along with a filter change, and then refill with the quantity drained. Never do a tranny fluid flush.
Thanks guys, I appreciate it. Going to be doing all the things you’ve mentioned this week. The one thing that’s been driving me crazy is the e brake light, it’s always on, I probably just need to open up the cover on top
and tweek with it a little bit, and yes, I’m positive the e brake is fully off when I drive.but anyways that’s another for thread.
ps: to answer the one fellow, I have cast iron heads.
1986 c4 78k miles
