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oil pan seal


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From what my manual states and searching the archives the oil pan can not be removed in the car in 93 STS. Has anyone replaced the oil pan seal without removing the oil pan? You would have to feed the seal under the oil pickup and it looks like it might be tight on the driver’s side. I’m working on a friends 95 Aurora 4.0 that looks exactly like my 4.6 STS as far as the pan removal is concerned. I first thought that the lower case was leaking but I have no oil above the pan to block area. The pan leaks all around the front and right side. I can also see what appears to be aftermarket gasket sealer in the joint. I don't know if this was put around the joint or somebody has had the engine out and tried to reseal the pan. I have tried to snug up the pan bolts a little with no luck. Any help or sugestions would be appreciated.


93 STS

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You are correct in that the oil pan cannot be removed with the engine in the car. Trying to sneak the seal in would be difficult at best. The oil pickup tube and screen extend down the middle of the oil pan and you likely wouldn't be able to get the one piece seal around it, without damage. I don’t think it is possible myself. When oil contacts the seal it starts to expand and will be very difficult to handle.

As you found tightening the bolts has little effect, the seal is silicone bead pressed in a groove. When tightened it is almost entirely compressed, over tightening will just strip bolts.

I found that most of my previous leaks, in this area, was oil seeping down the oil pan bolt threads. I have had very good results doing the following.

1. Drain the oil.

2. Remove several oil pan bolts (every other one).

3. Using spray brake cleaner, spray the area to flush off all traces of oil.

4. Spray the holes to flush out all oil residues.

5. Wait a few minutes and spray the holes again.

6. Use the spray cleaner to thoroughly clean the bolts.

The point here is to have both the holes and bolts DRY and clean of any oil residue.

7. Using Plumbers Pipe Thread Compound from the plastic jar, apply a coating to the bolt and screw it back into the hole. To judge the correct amount, when the bolt is tightened there should be a small amount left around the bolt head. Leave this exuded amount in place. Wipe off at a later date if desired.

Repeat until all of the bolts and holes have been cleaned and the coated bolts replaced.

Wait at least overnight (preferably 24 hours) then refill with oil.

I know there other automotive thread sealants, but I have used this method on several hard to seal locations and have had very good results.

Good luck, George

Drive'em like you own 'em. - ....................04 DTS............................


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In addition to growe3's idea you might consider brake cleaning the joint and when CLEAN and dry, press some RTV silicone into the joint with your finger. It must be oil free in order to work.


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I have the same problem and found out on further inspection that it is the oil manifold that is the culpert. If you look at the pan very close you will see a 1/4" piece between the pan and the lower case half. See if it is leaking from the upper side of this plate, start it up while you are under it and let it run while you look for the leak. Mine starts to come out pretty fast and it will be easy to see. There is no way to tighten the manifold so you have to pull the engine or trans axle to do the job :(


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