Posted: Sun Jul 30, 2017 6:21 am Post subject: HELP - Oil leaking from rear main seal
Hello
I just rebuilt from scratch a Willys MB. Not sure if the engine was actually from an MB or from a CJ2A, anyway, I rebuilt the engine with a ton of new parts since I wanted it to be “almost” brand new.
The 3 year restoration is almost over but I´m having a hard time with the engine since it is leaking motor oil VERY BADLY from the crankshaft´s rear main seal ( I used a brand new 2 halves rubber seal that I bought from a French supplier).
Because the seal surface of the crankshaft was not in a very good shape (it was pitted), Instead of having it polished (like I probably should have done) I decided to buy a BRAND NEW crankshaft.
I took off the engine, replaced the old crankshaft for the brand new one, installed a new rubber rear seal but when I started the engine, after a while the result was quite the same, ie, a BAD case of engine oil dripping at the bell house.
The oil is really engine oil, not transmission oil.
The leakage is not coming from anywhere else but the rear main seal. I say that because I checked the rear oil gallery welch plug and also the rear cam journal welch plug and I do not think that the oil is coming from this places.
Does anybody know how can I solve this problem??
Should I use a rubber seal or a rope seal?
The rubber seals that I installed (2 so far) were both WO800093. I heard that seals from this lot are all faulty. Is that true? If it is true where can I buy a reliable rubber seal?
If anybody could help me with this issue I would be very grateful because I am really tired of this everlasting restoration that should be over by now so I could enjoy my jeep while I’m young and of good health.
Joined: May 14, 2009 Posts: 972 Location: South Dakota
Posted: Sun Jul 30, 2017 7:40 am Post subject:
Willys Overland produced a bulletin that gave the crankshaft specifications on size limits that work with the lip seal. This has been discussed a bunch over at G503.com. What it boils down to is upon assembly, if the crank turns fine by hand, and not when the rubber seal is installed, you will burn it up and put rubber into the entire oilling system. The two rubber dowels that seal the sides of the rear main journal, also need sealant and be left about a 1/4 inch long so the oil pan will smash them up into their bores and expand them. I tried a lip seal once, and it locked my crank, so I've always used the rope. It drips some, but not enough to worry me. The WW2 T84 trannys are another source of bell housing dripping or pouring! . That's another topic. Personally, I'd just put in a rope seal. John
There are two types of cranks, the early rope seal crank and the later pre-formed 2-piece Garloc seal crank. They are machined differently at the sealing surface area. You cannot use a preformed seal on the older style crank. There is a sub-album in my photo album that covers all of this in great detail:
Thanks a lot for the tips and for all the precious and detailed information.
Wes, would you also recommend the rope seal like John did or, in my shoes, you would go for the rubber seal?
Im kind of confused about this because last week I asked the same question to the guys at Kaiser Willys and also another major Willys parts supplier in Arizona and both of them kind of told me to stay away from the rope seal.
The new crankshaf that I bought came from Sweeden and it is really new so the sealing surface where the rear seal works on looks like a mirror, no pits at all, very polished. The only problem is that I did not measure the crankshaft seal area diameter before installing the crank in the engine.
Wes, in case you too recommend the rope seal do I need to have that surface worked on untill it has the 2.302-2.312 (like I must do if I go for the rubber seal)?
I do not know if it has any influence in this matter but the new crankshaft that I bought is for a chain driven engine. My engine is gear driven but the seller told me that I could use a crankshaft for a chain driven engine in a gear driven engine but I could not use a gear driven crakshaft in a chain driven engine.
All I need is to solve this problem as soon as possible because it is kind of bringing my moral and motivation down. After 3 years working like crazy in that jipe and now that it is brand new and very much detailed I can not drive it because it leaks oil like crazy.
Thanks a lot again for your tips and for your patience. Forgive any errors you may find in my writing but, as you may have noticed, English is not my language.
I would not make any decision until you mic the seal surface. Does your new crank have bolt on counterweights?
The reason for the warning not to use a gear cam drive crankshaft in a chain drive is the gear drive crank is not bored with an oil passageway to oil the chain drive.
If your crank measures the smaller diameter yo can use either seal but be sure to use only fresh manufacture seals. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
My old crankshaft does have bolt on counterweights but my new one does not, instead it has drilled holes on the counterweights.
About the reason why not to use a gear cam drive crank in a gear drive only now I understood the reason why. Thanks a lot, it makes sense now.
About the rubber seal the only one I can find in my parts suppliers is the one thats has the reference WO800093. I read somewhere that all seals with this reference are faulty. If that is true where can I buy a fresh manufacture seal?
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. That's another topic. Personally, I'd just put in a rope seal. John
