What I learned about the rear main seal
07-14-2016, 08:39 AM
#1
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What I learned about the rear main seal
About a year ago I replaced the rear main seal on my 96 F150 with a 302. It still leaked oil, so I checked further and found a small pinhole in the side of my oil pan.
I filled the hole, but still had a bad oil leak, so I decided to go ahead and change my oil pan, which required separating the engine from the transmission again and hoisting the engine up about 8 inches.
Since I was doing that I decided to go ahead and change the rear main seal again, and this time I opted for the more expensive version of the seal. This seal came with a sheet of instructions that wasn't with the other seal I had replaced before. Going from memory, those instructions went something like:
"Some manufacturers drill the the holes in the back of the crankshaft too deep, which may result in oil seeping out through the threads of the bolts that mount the flywheel. This seepage is very easily mis-diagnosed as a rear main seal or oil pan leak. To avoid a leak, use a locking thread sealant compound on the flywheel mounting bolts".
Just to check, I went back to the parts store and asked them to check for the instructions in the less expensive seal, and there were none.
Had I known this the first time, I would have saved myself doing it a second time, which at my level of expertise and limited facilities, meant another 2-day job. This time I used a thread sealant on the bolts and after three days of driving am showing no leak at all.
I may be the only idiot who wasn't aware of this, but on the off chance there are others like me out there, I thought I would share.
I filled the hole, but still had a bad oil leak, so I decided to go ahead and change my oil pan, which required separating the engine from the transmission again and hoisting the engine up about 8 inches.
Since I was doing that I decided to go ahead and change the rear main seal again, and this time I opted for the more expensive version of the seal. This seal came with a sheet of instructions that wasn't with the other seal I had replaced before. Going from memory, those instructions went something like:
"Some manufacturers drill the the holes in the back of the crankshaft too deep, which may result in oil seeping out through the threads of the bolts that mount the flywheel. This seepage is very easily mis-diagnosed as a rear main seal or oil pan leak. To avoid a leak, use a locking thread sealant compound on the flywheel mounting bolts".
Just to check, I went back to the parts store and asked them to check for the instructions in the less expensive seal, and there were none.
Had I known this the first time, I would have saved myself doing it a second time, which at my level of expertise and limited facilities, meant another 2-day job. This time I used a thread sealant on the bolts and after three days of driving am showing no leak at all.
I may be the only idiot who wasn't aware of this, but on the off chance there are others like me out there, I thought I would share.
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techrep (07-14-2016)
09-11-2016, 09:24 PM
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Location: Fairfield CT
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Thank you for sharing! I am in the process of replacing the oil pan myself. I learned one or two about how to. Definetly get a good rear end seal and seal the treads. Cheers!