Rear Main?

[DLP]

For about the last 3 weeks I have had oil spots on the garage floor. About a half dozen drops a night. Seems to be comming out of the flywheel inspection cover drain hole area. Valve covers are dry. Motor is dry. The oil relocation lines have always been damp but never leave spots after parking. The drips are directly under the drain-plug flywheel area. I did replace the drain plug alreadt. Any other ideas?

[F9K9]

We can hope for it being the oil pan gasket but, I haven't heard of it being a problem in the 4.3L . You could try to see if the bolts are snug but, don't over torque them or you will have problems. Bumping up to 10-30W oil might be worth a shot too. Personally at 6 drops a night I would not worry until you have to start adding oil between oil changes. Bad time of year to try to clean up the area but, I would try that to narrow possible sources of the oil leak. Cheap brake cleaner with eye protection does a good job of cleaning it up.

[blks10]

If you are going to check and see if the pan bolts are snug, just go ahead and take it off and replace it. Save yourself some time

[HenryJ]

Not so easily done as it does require removal of the front axle as the simplest part of the process. You might as well plan on pulling the transmission if you are going that far as the one piece rear main seal will be easier to replace than the oil pan gasket. It and the front seal are much more common leakage points from what I have seen.

[F9K9]

Another last resort before selling, trading or replacing the rear main seal is Bar's Leaks Rear Main Seal Repair(click, it is really a link). It is claimed to have side affects but, I have not personally had an experience when I have used it.

Unfortunately I have had to get up close and personal with RMS leaks since I got involved with Jeeps and the 60 yr old 4.0L design. I even had a 4.0 not leak for all of 3 months, after replacing the rms, valve cover gasket, new oil pan, oil pan gasket and oil filter relocation gaskets. Get a drip pan for the garage floor and don't park in the in laws driveway with you CC.

[DLP]

Thanks for all the tips. I already tried the pan bolts. Not too worried about the oil spots. Just hoping it doesn't keep getting worse. I plan on pulling the tranny this summer for a rebuild. Figure that will be a good time to replace the RMS. If it hold up.

[DLP]

Not sure about the BarsLeak. Never been a fan of additives. But thanks for the lead. Might have to look in to it a little closer.

[F9K9]

Not sure about the BarsLeak. Never been a fan of additives.................

Don't get me wrong. I am not a fan either. It is a last resort tactic.

If, you are pulling the tranny anyway, then the whole problem is moot for now. I think the rms can be replaced without much more work but, I am just guessing here. Others would know much more than I do on the rms replacement of the 4.3.

[daevans315]

The oil pressure sending units on chevy small blocks(or 4.3's) are known to fail and look EXACTLY like a rear main. They are at the very back of the top of the block(kind of under the distributor) so when they leak, they run down over the rear main. You have to stand on your head and grow an extra joint in your forearm to even reach them but wipe off with a clean rag, run for 2 mins and see if you get more oil off after after the run.
Major pain to change but cheaper and easier than a rear main.

[DLP]

Thanks. I will look at it. I thought I did a good job of inspecting the top end. But have to admit I was looking at the valve covers more than anywhere else.

[HenryJ]

Wipe the back of the intake manifold and distributor base too. Either of those could be a source. I do like the pressure sender idea.
Unfortunately the oil from the interior of the bell housing usually indicates the rear main. The one piece rear mains are kind of infamous for some leakage with time.