OIL LEAK - 1994 Cutlass LQ1

[bluecalais79]

It's that time. The oil leak in the rear main seal of my 1994 Cutlass Supreme SL with the 3.4L motor has gotten so bad that it needs to come out for repairs. In addition to this being in need of replacement, I am going to have the oil pan gasket replaced as well, along with the 3 coils and the alternator while the motor is out of the car. In addition to that, is there anything else anyone can think of that should be replaced while the motor is out, as this would be a golden opportunity to get it done. The engine compartment will also be degreased to clean up the big mess this leak has been making.

It does not need a timing belt, water pump, or any intake manifold work as this was all done 5 years and 10,000 miles ago and no issues here. 

 

Edited January 3 by bluecalais79

[Psych0matt]

I should check my timing belt again, its been a while. I know it has lower miles-ish on it, but I've owned it for 15 years now. My list for this spring is a new starter (gets heat soaked and doesn't wanna crank), and a new window regulator for the drivers side, and while in the door I may clean out or replace the power lock motors, not sure if they're weak or just old and gummed up

 

Doesn't answer your question but it got me thinking haha

[bluecalais79]

Good call on that timing belt, over time they suffer age cracks; 15 years is a long time. 

[GnatGoSplat]

You probably already checked, but make sure it's not the distributor plug seal before tearing into it.  That can mimic a rear main seal leak.

[bluecalais79]

This is an excellent point, can you pinpoint and/or provide a photo as to where this is? For the life of me I can't find it and/or provide the page on the 1994 W Book that may provide a diagram where it is located? I would really prefer not to pull the motor if that can be avoided. Thanks for this memo, much appreciated

[GnatGoSplat]

It's in the valley right by where the transmission and engine block are joined together.  Oil will pool around the distributor plug (also called "oil pump drive") and run down the side right where the transmission mates to the block so where it drips on the ground looks very much like a rear main seal.  An O-ring goes bad on it allowing it to leak.  Shine a flashlight down there, and if there's oil pooled in that area, that's your culprit.  Unfortunately, yes, it's blocked by the rear head.  What most people do is lift it up as high as possible and clean it and the block as well as possible.  Some sandwich a thin O-ring under it, others RTV it.  My memory is hazy, but I think I may have done both.  On my pic, high pressure oil-resistant RTV is the stuff kind of squishing out from under it.  It's dirty because this was many years later, but it worked great.  Official GM procedure is to pull the rear head, but that's way, way too much trouble.

Edited 15 hours ago by GnatGoSplat

[White93z34]

I've ground the top ridge of the pump drive down slightly to allow for more room to work, then use a distributer gasket for a Lumina van with a 3.1, just give it a cut and slather it in RTV, seems to work well. and I'll be damned if I'm pulling a head just for that.

[Bake82]

If you need to pull the engine, I may consider the following:

 

 

- the block mounted crank position sensor. 

• They often get stuck in the block and break.  You either need to drill and put a screw in them to pull it out or they break too bad and you need to push it into the oil pan and hope it doesn't cause issues or pull the pan.  

- Steering Rack

• ensure there are no leaks.  Much easier to do without the engine in the car.  

- Engine and Trans mounts 

Edited 1 hour ago by Bake82