C4 oil leak
Thread Starter
Intermediate
Joined: Jul 2023
Posts: 46
Likes: 5
From: North Jersey
C4 oil leak
So I recently acquired a 1990 6 speed C4. There is a minor oil leak. The oil pan seems to have most of the oil on it. There's also some oil stains on the valve covers. A reputable mechanic said it is most likely the valve cover gaskets and not the rear main seal. He quoted me $1,200 to wash everything down, replace both valve cover gaskets and replace the oil pressure switch/sending unit. Seems a little high to me. My questions is, there is a mobile mechanic in my area who is familiar with C4's and the valve cover gaskets and said he can do it for $200. Now that seems TOO LOW! He has excellent reviews as well. Would you use the $200 guy??
Thread Starter
Intermediate
Joined: Jul 2023
Posts: 46
Likes: 5
From: North Jersey
I have a feeling the $200 mechanic doesn't know the full extent of the job and it will probably be more once he sees what it entails. OR i can just leave it as is and drive the car. Its a very very minor leak.
Drifting
Joined: Feb 2016
Posts: 1,384
Likes: 339
From: Simi Valley CA
The oil sensor is a common leak point. I have had a leaky one on my 89 c4, 92,c4 and even other cars. To do the oil sensor on the 90 you just need to unplug the sensor and then use a 1 1/16 or maybe it was a 1 1/8 deep socket and it was pretty easy to get to. The valve covers have the heat exhaust tube on the passenger side which comes off with a couple of wrenches, heat and penetrating oil. Not too bad for an experienced mechanic. So $200 seems about right. $1200 is too steep.
Thread Starter
Intermediate
Joined: Jul 2023
Posts: 46
Likes: 5
From: North Jersey
Got it. Thanks for the advice! Much appreciated!! Also the mechanic said that if the sensor is in fact leaking and it "blows", the engine will seize. Is that true??
Last edited by GPNJ; Mar 17, 2025 at 10:36 PM.
