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Old 03-31-2008, 06:13 PM   #1
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Default Found cause of ubiquitous 3800 rear cover leak?

I have it. You have it. That embarrasing 3800 rear cover oil leak.

Could this be the cause?

Haro sent me some rear covers. Here'* a full-body pic of one of them:
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Looking closely at it, and reading something about rear crankcase cover "plastic locating sleeves" in the FSM, I see this (closeup):
Name:  RC2.jpg
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The red circles show what I presume to be these plastic sleeves in various states of degradation. The green circle shows where one is completely gone.

Is it these sleeves crumbling that allows the oil to seep out?
Or maybe the degradation leads to loss of tension, leading to loosened bolts and the oil leak?

When I pull the engine to repair my rear cover leak, I'm going to try to pop out all the crumbling plastic sleeve residue and somehow shoot some RTV into the voids before tightening down the bolts.
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Old 03-31-2008, 07:29 PM   #2
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Hmmm.....I wonder how a S1 compares. I'm not torn down that far, but I could be pretty quickly.
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Old 03-31-2008, 07:33 PM   #3
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Quote:
Originally Posted by willwren
Hmmm.....I wonder how a S1 compares. I'm not torn down that far, but I could be pretty quickly.
thats the rear cover.
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Old 03-31-2008, 09:24 PM   #4
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Quote:
Originally Posted by willwren
Hmmm.....I wonder how a S1 compares. I'm not torn down that far, but I could be pretty quickly.
No rear cover on an S1..it uses a different rear crank seal and individual steel plugs to seal up the oil galleries.
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Old 03-31-2008, 09:43 PM   #5
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Quote:
Originally Posted by clm2112
Quote:
Originally Posted by willwren
Hmmm.....I wonder how a S1 compares. I'm not torn down that far, but I could be pretty quickly.
No rear cover on an S1..it uses a different rear crank seal and individual steel plugs to seal up the oil galleries.
im sure bill knew that, just had a brain fart. hey, he IS human
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Old 03-31-2008, 10:03 PM   #6
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He'* got one on a stand. If it had a rear cover, he could get to it.
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Old 03-31-2008, 10:27 PM   #7
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Double post.
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Old 03-31-2008, 10:35 PM   #8
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I have noticed the inserts on SII teardowns. On my first teardown, IIRC, I asked the dealer about them and received something like huh? By the time I have seen them, those inserts are usually 10 years old and have the consistency of hard wax rather than plastic. I have assembled rear seals with and without the inserts, and have had neither one leak. There is a gasket for the seal carrier that seals not only oil but coolant. One thing to keep in mind is that the lower edge of the seal carrier is actually the oil pan sealing surface for the rear of the pan. You need to make sure that edge is flush with the rest of the block so you don't create an oil pan leak. Once that is established, and the cover is located with four bolts in the corners, I would think you could loctite the little bolts or rtv silicone them if you like. I fill the crack between the carrier and the block with rtv silicone and strike it level with a single edge razor blade to minimize the potential for any seepage.

I assumed the purpose of the soft inserts was to allow enough play to get the block alignment correct. I do not think they affect the sealing of oil or coolant.
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Old 04-01-2008, 01:11 AM   #9
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I'm just wondering what it is that allows these rear cover bolts to come so loose...finger-loose in many cases.

Maybe the disintegration of these plastic sleeves allows the rear cover to "float" or shift just enough to loosen the bolts and leak oil. Why is it we don't see front cover oil leaks all the time?

I do know that the FSM says there should be no more than a 0.004 inch "step" between the bottom of the block and the bottom of the rear cover (the flushness with the block Bill Buttermore mentioned). And I expect all these plastic alignment sleeves to be fubar'ed. So I picked up a J-41349 Crankshaft Rear Alignment Tool and a J-38196 Crankshaft Rear Oil Seal Installer off EBAY to make sure I get that cover lined up and the new seal installed right. This is not something I want to have to go back and redo :P
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Old 04-01-2008, 03:32 AM   #10
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Has anyone noticed problems with gasket itself (softening, hardening, cracking, dexcool degradation, etc.)?
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