I acquired my fathers 1999 C5 after he passed away and brought it back to KY with me last summer. I have been doing some maintenance work on the car - I am a novice but not too afraid to try some things. I have so far replaced the harmonic balancer (and ancillary items on the front of the engine, tensioners, etc.), sway bar end links, fixed the rocking in the seats, replaced a cracked radiator, and most importantly replaced the sagging sun visors, among other annoyances.

My problem is the oil leak that has grown progressively worse. It is leaking underneath the front center of the car at the rear of the engine. Inspecting underneath the car to my untrained eye seems to be coming from the back of the engine, although I could not rule out an oil pan leak. I was leaning toward replacing the rear oil pan gasket and keeping my fingers crossed although I do not believe that is the answer.

Then I thought to myself - replace the upper /front (??) oil pan gasket. Although when looking at videos of how to do that - it looks like it wouldn't be that much more trouble to bite the bullet and replace the rear main seal oil cover and gasket at the same time.

Researching that a bit further I am not finding step-by-step instructions for this task like - specifically, gaining access to the rear main oil seal/cover.

I seek your collective wisdom. I do not need this car for transportation, I can take as long as I need to do the job. the estimate that I got to replace the rear main oil seal / cover locally was $3,300. Financially I could do it - but why not do it myself if I can?

Is special equipment required, especially to get the rear suspension out of the way (if needed)? I do not have a lift so this would be jack stands and on my back.

I am intimidated by the job, but I was intimidated by the harmonic balancer too and that went pretty smoothly. Are there some step-by-step instructions out there for this job to which I could refer?

 

First, I would clean the entire engine off so you can properly track where it is coming from. Surprisingly, a lot of the times a rear most oil leak is either valve covers or the oil pressure sensor leaking.

To do the rear main though, there are plenty of step by steps but you need to search for step by steps on replacing a clutch to seek what you are after. And if you are going that far with it, just put a new clutch and slave cylinder in it at that point.

Other option is drop the cradle and pull the engine forward and off the torque tube.

 

Moved to C5 Tech for more discussion.

 

Thanks for your help. I actually started with replacing the Oil Pressure Sensor (and install a relocation kit).

I did try cleaning off the car and was not able to clearly identify the source of the leak. But it can't hurt to try that again.

I also failed to mention that this C5 is an automatic. Would your advice to research clutch replacement translate to an automatic transmission?

 

Well, that makes it easier but also poses a new challenge. If you separate the engine from the torque tube, there is a clamp on the flex plate that grips onto the input shaft of the torque tube. When putting everything back together, this clamp needs to be left undone. Once the entire assembly is all put together and ready to run (besides the clamp) you need to let the motor idle and get up to operating temperature for a few minutes or so.

Once it's been at operating temp, you can then shut the car off and let it sit for a few minutes. Then using the inspection hole in the bellhousing (the large open slot) you can go through that to retighten the input shaft clamp.

The reason behind this method is that if the clamp is done as soon as the car is all back together, when the engine warms up and the alloys expand, the input shaft could put pressure on the crankshaft and causing excessive thrust bearing wear. Which then results in you pulling the motor to have completely disassembled and rebuilt.

 

Moved to C5 Tech for more advice.

 

You've done some nice work on your C5. Congrats, and it seems like you're enjoying the journey. We like pics - post some up of yours.
I had a rear main oil leak in our 65 Sting Ray. Here's my post on the C2 forum regarding how I fixed it. I was surprised with the results, and the car still doesn't leak a drop of oil.
Another member posted about the Blue Devil stop leak, I have no experience with that.

Unlike some other stop leaks I've used that are like thick oil, this stuff is clear and as thin as water. I just changed oil, added the bottle and drove it. I recently had a small transmission leak in our A4 C5. I pulled the transmission pan, changed fluid and filter and added a bottle of AT-205 and drove the car. So far, no more leaks. If it doesn't work, you're only out about $20.
Good luck!

 

I have also used Blue Devil stop leak. The stuff does work well, real well, actually.....

 

Thanks for the tip. to be honest, I have always steered clear of additives for leaks - but maybe the time has come?

 

Be prepared to replace the upper oil pan gasket and the rear seal and cover gasket. There are videos on YouTube but it is not easy without a lift, you have to be really creative.