rear main seal issues

[blue2T]

I know this is an old subject, but would like to get an opinion from the experts!
I have a leaking rear crank seal after only 1800 miles. I am about 95% sure that leak is comming from the shaft lip seal(nothing is for certain!). Here are the facts that I know:
Fel pro 40613 lip seal
Chinese stroker crank--with knurl.
Sides of cap sealed with Black Ultra silicone. No sign of any leakage there.

See attatched photo's of the leaking seal compaired to a new seal. You may have to reduce to about 150% for clarity.

Thanks, Earl

 

[wickedtt]

I know you are looking to the rear seal as the problem but how about the knurling on the crank. I have seen a few of those aftermarket cranks with the knurling lines cut a little too deep.

 

[YAKO]

Yes i have to agree i saw one china crank installed in my buddys stroker the groves were really deep and sharp,, a mild polishing and running a ele vacume pump no pcv valve and the rear main is bone dry after many 1/8 mile passes and driveing to the track ,,????

 

[joey316g]

x3 on the grooves

 

[getchasum]

Earl, are you thinking the aggressive knurling on the crank compromised the seal itself?

 

[blue2T]

That was conclusion I came to also. The knurled seal surface on this crank is better described as cuts. can't measure them, but they are probably .030/,050 deep. I haven't seen an original GM knurl, but other makes that I have sceen are nowhere near this deep!
No vacum pump, so I propose to break the sharp edges of the "cuts" with a pointed arkansas stone and a good polish.

 

[blue2T]

Scott,
Yes, hard to get good measurement on thickness of the seals. But there was at least .015/.018 wear on both halves. So the ID of the seal has been worn down at least .030. On the leaky seals, looking at photos, there is also a grove on the flat seal surface. I think that the knurled cuts were too sharp and too deep, and it chewed up the seals. That's what I think from what I see. Any one else been able to sucessfully deal with this? At this point a vacum pump isn't an option.

 

[YAKO]

Ele vacuum pump was the type that only came on with a hobbs switch when boost started ,,see racetronics

 

[pdzz]

I just bought the wife an 86WH1, with a chinese crank... It leaks too. I've replaced it twice(seal) with no luck. I'm almost thinking of trying the rope seal!! Phil.

 

[chopped39]

Read the last thread abiut rear main leaks with aftermarket cranks. The rope seal was the fix. If the knurl was not there there would not be an issue. The crank companys are going off stock design. newer 3.8 engines dont leak like these beacause of no knurl and its a way better design.
I bet if the crank companys knew they didnt have to knurl the crank they wouldnt. Im sure it cost more to do that. I wonder If a crank welder could weld the grooves and then repolish the journal so its smooth

 

[YAKO]

Well if your going to have no knurl on the crank you better have a knurl on the surface of the seal (chevrolet small block) its either a knurl on one or the other