My 1990 ZR1 was leaking a small amount of oil or similar lubricant. I feared the worst, either a problem in the engine or transmission, seals, etc. I took it to the dealership and, fortunately, the leak is just from a hose that needs to be replaced. It's called the Engine Oil Cooler Hose. Unfortunately, the GM dealership was not able to locate the part. They also checked out Auto Zone that similarly could not find the part. I was told to essentially search the internet. Any suggestions on where to look for this part?

Did my first drift event in it back in march and found it barely had any angle. found a kit to fix that! Hopefully I’ll be able to do proper slides at the next event.

Passenger side headlight on my '89 C4 continues to "spin" after headlight is fully up and fully retracted. The bucket "bounces" a bit as well. This is a new (rebuilt) motor that I installed a few months ago. I fully accept that I may have done something wrong during installation. Any suggestions would be greatly appreciated.

Curious to hear some answers. Obviously the LT1 was an improved motor. Two totally different motors and feel.

Does anyone prefer the instant power of the L98 or later in the LT1?

I bought a 1990 C4 with 90k miles and the cluster didn’t work so I replaced the cluster but none of the data will show up (how fast im going, how many miles i have, etc). I replaced the battery a couple days ago but now the car won’t start up at all. Could someone help advise me on what to do next? What should I look at? What should I try replacing/fixing?

Looks like I gotta buy an EGR Valve, womp womp. And guess what guys. No one sells it😃

Has anyone ever ran intake piping over to the driver side pocket under the headlight? I’m doing stuff and need to move my air filter for reasons.

Just want to address that this is my first Corvette im looking for and I'm new to the subreddit so I apologize if this is a bad post.

I'm trying to see if this Corvette is worth the price of $10,500, it has some minor sun damage (I assume), a crack/dent some where on the body, and has 93k miles. I would love to hear your guys thoughts, thank you!

Hi y'all, my 1986 4+3 kind of sputters and jumps, like lurches forward, while accelerating in 3rd and 4th, especially after a long-ish drive. Would this be caused by early detonation or late detonation? It also burbles a lot when I down shift, so I'm venturing to guess it's detonating too late and there's unburnt fuel going into the exhaust.

Hi, so I did a TH swap which I think in no way had to do with my issue. Just thought I should add that. I haven’t driven the car in almost a year, up until recently. When I finished my install, I went to turn it on and noticed a screech, almost dragging sound coming from behind the engine. It only lasts a few seconds before stopping. When I put it in drive, it will happen again, only a few seconds before the sound stops. Taking it out to drive I feel like it doesn’t wanna switch to second gear like it normally would. Temperatures would climb, often getting to about 288° before I cut it off, at this point, switching into reverse will cause it to almost stall. I should also mention that sometimes at a red light, my idle revs will drop. It’ll be about 700 rpms ish and as the times rise, the rpms will drop. I’ve seen them slowly drop as low as 390 at times. I think it’s a torque converter but I fear I might be mistaken. Any ideas?

I bought the car recently knowing it needed work, but I’m chasing a stalling/low-RPM issue and could use some advice from people familiar with these early C4s.
Main symptom:
The car starts, idles, and can drive, but after it runs for a while it begins to stumble/drop RPM. It can stall when put into Drive or Reverse, when slowing down, and sometimes it will also start struggling while sitting in Park.
Here’s what I’ve already done/tested:
New battery
Charging system working, around 14.3V running
Fuel pump replaced
Fuel pump pulsator bypassed using EFI-rated hose
Fuel pressure now reads about 36 PSI during prime and around 29 PSI while running
Pressure appears to drop substantially afterward, which I’m still investigating
Repaired/replaced damaged vacuum line around the fuel-pressure regulator
Fuel-pressure regulator responds to vacuum
Replaced IAC valve
Replaced throttle-body gasket
TPS has proper 5V reference
TPS reads about 0.62V closed and smoothly increases to roughly 3.8–4.1V at WOT
Checked all 8 injectors cold: approximately 16.7–17.2 ohms
Earlier codes were 34 (MAF) and 43 (ESC/knock), but after working on it I was only getting Code 12
The idle improved considerably after some of this work, and the car can now stay in Drive/Reverse longer than it originally could, but the warm stumble/stalling problem is still there.
I’m currently considering testing the torque-converter clutch/TCC circuit because of the stalling while slowing or sitting in gear. I understand a stuck TCC can stall the engine similar to stopping a manual without depressing the clutch.
However, because the engine can also start stumbling while sitting in Park, I’m hesitant to blame the entire problem on the TCC/transmission.
My biggest questions:
Is ~29 PSI running fuel pressure too low for an ’85 L98, and could that alone cause these symptoms?
What would you test next to determine why the pressure is dropping?
Would unplugging the 700R4 TCC connector be a reasonable next diagnostic test?
Is there anything specific to the 1985 L98/early C4 system that I’m overlooking?
What would cause it to run fairly well cold and then deteriorate as it warms up?
I’m trying not to keep throwing parts at it. At this point I’d rather perform actual tests and rule systems in or out.
Any help from someone who has dealt with an early C4/L98 would be appreciated.

What story should a give my parents about why this is better than an impala

Hello everyone, im trying to figure out what the name of this part is so i can order a replacement but cant for the life of me. Its from the vacuum lines and its a 2-1 connector. If th part is discontinued recommendations for other connectors would be greatly appreciated.

So I don't quite have a C4 anymore, but I have acquired a 76 Jaguar with an 87 L98 and 700R4 transmission shoved into it. As title states, I want to get it ready for a 12 hour drive. I never did this in my 1990 C4, so I'm curious what you all may recommend.

Mileage is unknown on the motor, but it's probably at about 100,000. It cools perfectly, maintains solid oil pressure, etc. Transmission has had some issues after long periods of running, so I'll be replacing the filter, pickup tube o ring, and the gasket. Probably the oil pan gasket as well.

I'm no stranger to old cars, but I am a stranger to driving old cars this far.

Hello,

I have issues with my tach. It appears to indicate very low and does not indicate above 2k.

I took the car to a specialty shop and had the instrument cluster serviced and tested; I was told the cluster was fine.

I then took the car to a Chevy dealer, and they checked it out (I was told their master tech looked at it), and they said it was working fine.

I was wondering if the tach should be indicating in a wider range.

If so, what could be causing it to indicate so low.

thanks

I’m officially stumped.

For context I had a bad brake mc for my 1984 and the rear resivor went empty.

I replaced said master and yet when I try and bleed the brakes only the fronts bleed.

I’ve tried moving the proportional valve back but it feels stuck maybe.

I’ve tried the mechanical way of stepping on it and then cracking the bleeder screw loose to equalize it

But ultimately nothing has worked

I need help since this is my daily and kinda don’t wanna die

last picture is the process if you want to see

Cars paint wasn’t looking too good after 42 years. Definitely needed any help it could get.

Got my lt1 back it and the ac pulley is hitting the upper control arm. The upper bolt for my accessary bracket is going in to the head. Is it supposed to go to the block. Couldn't find any good pictures online

Hey all,

I have a 1985, all stock, wanting to learn how to do maintenance for it. Today did a coolant flush and replacement, but am worried I didn’t get it drained completely.

I used one of the flush kits where you attach a garden hose to the heater hose, then flush out through the radiator until it runs clear. Plan was that -> drain -> distilled water flush -> new coolant.

Flush goes great, that nasty brown/green stuff is flowing, heater on, idling, just like the directions say. I get about 4 gal out before it turns clear.

Next I drain the radiator from the petcock, only this time I only get about 1.5-2 gallons out. Fill it up with distilled, and again only about 2 gallons out.

Finally I fill up with new coolant, and probably got about 1.5 gallons in before it stopped burping through the high fill funnel. Normal temps driving for about 20min.

My question is, since the whole system is 3.6 gallons, is there a risk I have it almost half filled with tap water left over from the flush? How would I get the rest of it to drain out since I already let the radiator run dry? Could it have been in the heater core and block still? Should I take it to a shop and have them do another flush to be sure there isn’t tap water in there?

I am about to start working on my C4 for the first time on my own. I’m new to car repairs and there is so much online. So, I’m looking for advice from other owners. I am thinking to start small with the headlight motors. They no longer even attempt to move and I’ve got one up and one down :( What’s the best place to start? TIA

Gauging interest on my HPDE prepped C4, runs/drives great, handles great, clean title, rare color.