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Rear crank seal install advice needed

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Old 03-22-2011, 02:36 AM   #1
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Default Rear crank seal install advice needed- pics added

I'm putting my rear cover on tomorrow and have a question. I've read about problems using the new GM seal for forced induction and it seems that there have been a few problems with the seal leaking because it's not designed for much positive crankcase pressure. I've looked at the seal and it has a ribbed surface followed by a lip that points outwards. I've heard that some guys are installing these seals backwards to prevent leakage due to blowby pressure under boost.

For you guys with forced induction: which way do you have your new-style GM rear seals in? Have you had any leakage? Do you recommend another type of seal besides OEM?

The old style GM seal with the double lip is unavailable to buy but would probably be a good option. What sayeth the FI engine builders?

Last edited by swift700; 03-22-2011 at 04:11 PM.
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Old 03-22-2011, 02:52 AM   #2
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Old 03-22-2011, 06:33 AM   #3
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Not an expert but what about the rear seal from a LSA for a Cadillac CTS-V thats FI or a LS-9 ZR-1
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Old 03-22-2011, 10:57 AM   #4
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Not an expert but what about the rear seal from a LSA for a Cadillac CTS-V thats FI or a LS-9 ZR-1
Not a bad idea. I think I'll look into that. Thanks.
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Old 03-22-2011, 11:17 AM   #5
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I had major leaks, so I installed it backwards and it fixed it. It will also depend on ring gaps and PCV system.

Seems to me there is no problems with installing it backwards in anycase, and stock boosted trucks probably dont have issues anyway due to the above reasons
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Old 03-22-2011, 03:01 PM   #6
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Quote:
Originally Posted by swift700 View Post
I'm putting my rear cover on tomorrow and have a question. I've read about problems using the new GM seal for forced induction and it seems that there have been a few problems with the seal leaking because it's not designed for much positive crankcase pressure. I've looked at the seal and it has a ribbed surface followed by a lip that points outwards. I've heard that some guys are installing these seals backwards to prevent leakage due to blowby pressure under boost.

For you guys with forced induction: which way do you have your new-style GM rear seals in? Have you had any leakage? Do you recommend another type of seal besides OEM?

The old style GM seal with the double lip is unavailable to buy but would probably be a good option. What sayeth the FI engine builders?
I read all that too. I installed the new seal on my latest build & it hasn't leaked a drop. I read somewhere that the new seals are "thinner" & one must insure that they are fully seated.

Well they were correct, it sets deeper in the opening, not flush. I hope that makes sense. I did not install it backwards, I do not understand how that would work on the new seal I used.
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Old 03-22-2011, 03:43 PM   #7
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Here are some pictures of the new GM seal for clarification. As you can see, there are two sealing surfaces. For reference, the yellow side of the cover goes towards the outside of the engine and the silver is the inside. There are two sealing surfaces- one is a ribbed rounded surface and the other is a lip seal. Neither look as though they would seal much pressure into the engine when installed as per the manual.

From the outside looking in:


The lip seal:


The rounded ribbed seal:


From the engine side looking out:


The rounded seal and lip seal both taper towards the outside of the engine.
It doesn't look as though this would hold much pressure in. You can see that if the seal were installed backwards that both surfaces would act to keep pressure inside the engine. Pressure would expand the lip seal towards the crank surface, tightening it up.

One disadvantage with installing it backwards would be that it would not seal against debris getting in very well. Not good for an off-road rig.
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Old 03-22-2011, 11:54 PM   #8
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I've heard about the backward install trick also, and that the seal is actually marked "this side out" or something like that, and to disregard that recommendation and actually install it "that side in" lol.
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Old 03-23-2011, 12:06 AM   #9
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i put mine on the correct way and just made sure i have plenty of breathers to let most of the crank case pressure out, havent had any problems yet.... Drivers side to a canister, pass side with the filter that goes where your oil cap normally would, ls6 valley cover with a little breather on it
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Old 03-23-2011, 12:47 AM   #10
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Also have heard the rev trick on that seal... The vent in the valley cover is new to me however.. I think that will be a next mod I do, to insure the case is venting enough.. There is plenty of ways you can vent the case, even buy running lines from the covers to the exhaust... I am venting the pass side into the air, still have the pcv on the driver side hooked up.. Thus far no issues..
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300dt, back, backwards, chevy, correct, crank, crankshaft, install, installed, leaking, lip, location, rear, seal, trucks

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