360 Rear Main Seal Leak Question --- AGAIN
#1415114
04/06/13 09:33 AM
04/06/13 09:33 AM
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Joined: Jan 2010
Posts: 509
Middle River, MD
Mapandjlp
OP
mopar
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OP
mopar
Joined: Jan 2010
Posts: 509
Middle River, MD
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I've had what appears to be a slight drip from the rear main on my 360 since assembly last winter. After about 4,000 miles last year, it hadn't changed. A few drips on the floor. This year, I switched from HR2 (10-30) oil to HR1 (15-50) oil to get the pressure up a bit. It was carrying about 20 to 25 psi at idle. Now the pressure is better, about 35 psi at idle, 70 at high RPM, but the leak has increased tremendously. After the inaugural trip for the spring last weekend, I went out of town for the week only to come home to a CD sized puddle under the car ('70 Challenger).
Before I pull this thing and replace the rear seal, can you guys confirm that this sounds right?
For what it's worth, I can't find any leaks up high; intake, sending unit, valve covers, etc.
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Re: 360 Rear Main Seal Leak Question --- AGAIN
[Re: MoparforLife]
#1415118
04/06/13 09:55 AM
04/06/13 09:55 AM
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Joined: Jan 2010
Posts: 509
Middle River, MD
Mapandjlp
OP
mopar
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OP
mopar
Joined: Jan 2010
Posts: 509
Middle River, MD
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Quote:
Are you sure that it is the rear main seal??? It could also be the rear pan seal that if not installed carefully have a tendency to leak. Must make sure that the grove in the camp is very clan and dry and that the indentations in the cap/block are clean so that the end tabs of the rubber fit up tight in these. I have had the best luck putting this seal in dry and using just a tad of silicone in the coners where the pan gasket meets it.
I've read now, as well, that some folks put sealer between the rear main cap and the block. I did not. Could it be bleeding past that?
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Re: 360 Rear Main Seal Leak Question --- AGAIN
[Re: Mapandjlp]
#1415119
04/06/13 12:21 PM
04/06/13 12:21 PM
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Joined: Aug 2006
Posts: 2,505
God's Country Maryland
GODSCOUNTRY340
master
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master
Joined: Aug 2006
Posts: 2,505
God's Country Maryland
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Oil pressure doesn't keep the seal tight to the crankshaft, the seal has some crush built into it and when the cap is torqued down, that compression pressure keeps the seal tight to the crank. I always put sealer between the cap and block, if it's not there it could cause your leak. A seal installed backwards would also make it leak, or any damage to the sealing area of the crank. I also put a little drop of sealer on each end of the seal where they butt together, just to be sure. One other possibility is that the rear main bearing has a lot of clearance causing excess oil to flood the seal forcing it to leak. When you have it torn down check the bearing clearance with plasti-gauge, if it's more than .003" it may be your problem.
I love the smell of Deer guts in the morning, it smells like... VICTORY!
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Re: 360 Rear Main Seal Leak Question --- AGAIN
[Re: GODSCOUNTRY340]
#1415120
04/06/13 12:26 PM
04/06/13 12:26 PM
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Joined: Jan 2010
Posts: 509
Middle River, MD
Mapandjlp
OP
mopar
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OP
mopar
Joined: Jan 2010
Posts: 509
Middle River, MD
|
Quote:
Oil pressure doesn't keep the seal tight to the crankshaft, the seal has some crush built into it and when the cap is torqued down, that compression pressure keeps the seal tight to the crank. I always put sealer between the cap and block, if it's not there it could cause your leak. A seal installed backwards would also make it leak, or any damage to the sealing area of the crank. I also put a little drop of sealer on each end of the seal where they butt together, just to be sure. One other possibility is that the rear main bearing has a lot of clearance causing excess oil to flood the seal forcing it to leak. When you have it torn down check the bearing clearance with plasti-gauge, if it's more than .003" it may be your problem.
Thanks for the feedback! All good stuff. I built the motor myself and checked the clearances on assembly. The rear main was at .002. Of course, that doesn't mean that it still is! I'll double check when I have it apart.
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Re: 360 Rear Main Seal Leak Question --- AGAIN
[Re: Mapandjlp]
#1415121
04/06/13 12:28 PM
04/06/13 12:28 PM
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Joined: Jan 2003
Posts: 25,200
Upper Midwest
MoparforLife
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 25,200
Upper Midwest
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Quote:
Quote:
Are you sure that it is the rear main seal??? It could also be the rear pan seal that if not installed carefully have a tendency to leak. Must make sure that the grove in the camp is very clan and dry and that the indentations in the cap/block are clean so that the end tabs of the rubber fit up tight in these. I have had the best luck putting this seal in dry and using just a tad of silicone in the coners where the pan gasket meets it.
I've read now, as well, that some folks put sealer between the rear main cap and the block. I did not. Could it be bleeding past that?
We have had batter sealing using no sealer between the rubber end gasket and the pan. Making sure that all surfaces are clean and dry seems to give a better sealing surface. along with the recesses that the end tabs fit into. If they are not clean the gasket cannot fit down in the cap groove tight. Like I said the only sealer we use is a small dab of silicone in the corners where the pan gasket meets the cap rubber. so far haven't had a leakage problem on 360's
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Re: 360 Rear Main Seal Leak Question --- AGAIN
[Re: Mapandjlp]
#1415122
04/06/13 12:34 PM
04/06/13 12:34 PM
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Joined: Aug 2006
Posts: 2,505
God's Country Maryland
GODSCOUNTRY340
master
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master
Joined: Aug 2006
Posts: 2,505
God's Country Maryland
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One more thing to do, I also put sealer in the channel the seal goes into. Make certain there are no scratches or marks on the crank's sealing surface where the seal rides. I've seen gouges there that would also cause a leak.
I love the smell of Deer guts in the morning, it smells like... VICTORY!
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