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Oil leak - pan or rear main

2K views 13 replies 7 participants last post by  guitarnut 
#1 ·
My local diesel shop told me I have a rear main seal leak. I know it's no super common on powerstroke so I got a second opinion. I hoped it was the turbo seal. The second opinion is oil pan gasket from a reasonably reputable shop but they only have 1 diesel mechanic. Both are around $1000 to repair and well beyond my capabilities as an IT guy. There is no where to go for a 3rd opinion.

What do you experts think?

How severe is either one? Sitting on the side of the road severe?

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#2 · (Edited)
Well, the rear main you have to drop the transmission - the pan you have to invert the engine to do it right (or go the Morosso gasket route - still not fun). That's a rather major difference so I'm a bit confused as to the similar price.

That being said, rear mains on these things are rather rare (but still happen). Oil pans are far more likely.

The severity is yours to decide - mine leaked for *years* before I tackled the problem. (Edit - I'm an IT guy, I do this for fun.)
 

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#3 ·
Are they SURE it's the RM Seal? It is rare, but that doesn't mean it can't be happening.

Do you have oil in the valley? I ask because there is a weep-hole in the back of the valley that allows oil to leak down the back of the engine.

How bad is the oil leaking? Dripping "some" or constant stream? If dripping some, I wouldn't worry too much about it. Obviously, if it is heavier than that, I would say it needs attention.
 
#4 ·
Make sure the pan bolts that you can easily get to are tight. If you find some loose ones, remove what it takes to get to the rest of them, particularly at the rear. Even an IT guy can do it.

My new to me 30 year old ZR-1 had a severe engine oil leak. I put it in the air to check out what it might be, and I concluded it was probably the pan-to-block interface. The bolts I could get to were quite loose. I spent the next 4 hours removing heat shields and frame braces to access the rest of them, and they were loose too. It's been a month and 500 miles, and it's now dry as the day it was built. I bring this up because the Powerstroke and the LT5 use the same "gasket-less" pan installation method. You might get lucky and slow the leak down to the point it is tolerable.
 
#5 ·
I made that comment about it leaking from the top. Neither shop found it and I know the second one looked for sure because he was asking me questions about having fuel lines replaced.

Can they do both the rear main and oil pan at the same time? It seems with what they have to do for the oil pan the rear main would be easy access.

Also, pulling the engine on a 20 year old truck. Am I just asking for more Gremlins?

Right about now I'm wishing I had bought that new ram Cummins. Over this year I will have spent 40% in maintenance compared to what I paid for the truck.

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#6 ·
The engine pulling question - Not if it's done right. I did have some issues that I brought about myself in doing it. A *good* shop should have no problem. However, I also took the time to do a *lot* of other maintenance when I was in there and swapped a bunch of parts.

You can easily replace the rear main if you're doing the pan gasket the recommended way. If you are *just* doing the rear main, the oil pan gasket is not going to happen properly (unless you go Morosso or...) you can try;

The short version of the oil pan is that the residual oil will *always* contaminate the surfaces where the Ford/International RTV will go. If it gets contaminated within the 24 hours of application, it *will* fail. There is a guy on here that dropped his pan in the truck and let it drain for 5 days before he applied the RTV. He claimed it worked (no residual contamination) however I never saw a long term after-action report to see if it failed months or a few years later. Plus it's a B!TCH to get all the old RTV off properly in the truck.
 
#7 ·
It all depends how bad it’s leaking, if it’s just a little it’s fine, even if it’s pretty bad you still won’t hurt anything, just have to keep it topped off haha. But if you want to have it fixed, and you’re SURE it’s from either the pan or rear main, I’d pull the engine and do both. Dipstick tube adapter too. 7.3s are easy to pull, you can have it done and back on the road in 2 days


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#8 ·
The other thing to look for is a rusted oil pan. Fairly common on these trucks if they're exposed to salt in the winter. Like others have said if it's just an annoying leak you could try tightening the pan bolts but don't overdue it, and wait awhile. Also like said above take a look at where the dipstick goes into the pan, it's another problem area.
 
#9 ·
So I had the oil pan resealed and the rear main seal done. Fooking thing is still leaking. Drops about a quarter size drip of oil from the cover that is over the flywheel. They said they checked and it wasn't the turbo leaking or something draining from the valley. Had I not just paid about $1500 for this work I would just say F it but I guess I will drop it off for a recheck when I pick up my Hyundai accent commuter car...$1100 on that for new tires, alignment, control arms (ball joints are not replacable but the whole arm gets replaced), and some thing it needs for alignment.

I still regret not spending $48k on a new ram Cummins. I guess had it been a new truck and not an old 7.3 that 1500 bill would have been 6000.

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#10 ·
The issue I had a while back was the drain plug on the HPOP became loose & started leaking into the valley area which drained into the weep hole at the rear of the valley into the bellhousing area making it look like the rear main was the culprit.
It was pretty obvious where the leak started once I started looking.
 
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