98 Jeep 4.0 Rear Main Seal still leaks!

[wn1998]

I have replaced the rear main on my 98 grand cherokee 2 times within the last two years and I still have a nickel sized oil spot on the driveway every morning.

I know it isn't the seals, why could it still be leaking.

on a side note, I have also replaced the head gasket, exhaust gasket and the exhaust gasket in the last year.

 

[JohnBrowning]

The crank is worn down in the seal area. Did you see a dice grove int he crank that looked like it was machined their? Well that grove should not be their. You probably need a crank saver pressed onto the end of the crank. Then it will not leak with the new seals.

 

[Colt45ws]

Sure its oil? Maybe it is the trans?

 

[wn1998]

It's not red, so I assumed it wasn't trans oil. The leak isn't that large because on my 4k oci's I don't need to add any oil. It's just very annoying

John, tell me more about what a "crank saver" is and where can I find one?

 

[Steve S]

Originally Posted By: JohnBrowning
The crank is worn down in the seal area. Did you see a dice grove int he crank that looked like it was machined their? Well that grove should not be their. You probably need a crank saver pressed onto the end of the crank. Then it will not leak with the new seals.
+1 or the crank bearings are worn allowing too much play in the seal area

 

[Chris142]

Originally Posted By: wn1998


John, tell me more about what a "crank saver" is and where can I find one?
you wont find one. Your Engine uses a 2piece seal and the crank has a flange on the rear where the flywheel bolts to. The flange is larger than the seal area.

 

[440Magnum]

Are you double-dog certain its not the valve cover gasket leaking and running down so it drips off the bellhousing? Pretty common occurrence and an easy fix.

 

[MNgopher]

Originally Posted By: 440Magnum
Are you double-dog certain its not the valve cover gasket leaking and running down so it drips off the bellhousing? Pretty common occurrence and an easy fix.



That's what it was on my Cherokee - not a rear main seal. Check the valve cover gasket, particularly at the back of the engine

 

[mechtech2]

A 'Speedy Sleeve' is also known as a crank saver.
It is a thin steel ring that goes on the end of the crank [front or rear]. Now you have a virgin non grooved surface for the seal to ride against. But you need their proprietary seal with it - no big deal.

 

[47HO]

Check the oil filter mount.

 

[Kruse]

Originally Posted By: mechtech2
A 'Speedy Sleeve' is also known as a crank saver.
It is a thin steel ring that goes on the end of the crank [front or rear]. Now you have a virgin non grooved surface for the seal to ride against. But you need their proprietary seal with it - no big deal.


But as reported by Chris142, and not to get the OP's hopes too high, there isn't one made for the rear main seal on this vehicle.
Some later vehicles with the one-piece rear main might get repaired this way.

 

[Greaser]

You can get a "double lipped" rear main seal from Fel-Pro for the 4.0L engine just can't remember the exact part number off hand.This will solve the grooved crank.You can't put a speedy sleeve on the rear due to the casted flexplate/flywheel bracket outback...it's just up front that it can be done.

 

[Greaser]

http://www.dailydriventj.com/forum/viewtopic.php?t=811

 

[Colt45ws]

FelPro BS40612
Rear Main Seal Set; Rubber; Two-piece; Double lip; Improved design

 

[Greaser]

Originally Posted By: Onmo'Eegusee
FelPro BS40612
Rear Main Seal Set; Rubber; Two-piece; Double lip; Improved design
Thank you sir!

 

[andyd]

I used to have a Dart that used a pint of ATF a month. It leaked it from the out put seal and made a great rust inhibitor. A minor oil leak isnt a bad thing. Rig a tray with some kitty litter on your parking space.

 

[mechtech2]

Loose bearings at either end or a bad timing chain can cause leaks at the end seals. There is too much flopping around and the oil kinda pumps out of an otherwise good seal.

 

[Eddie]

Plugged PCV system allowing pressure in the crankcase to build up

 

[JohnBrowning]

Really their used to be one that did not use a special seal. Sure the lip load was increased due to the increase in the diameter of the end of the crank but OEM seals still worked they just wore out a tad faster so instead of 120,000 miles per seal you might only get 80,000 per seal before they leaked......I am dateing myself since it would appear that they changed the system to include a better seal to make up for the increased lip load! When they first came out they where all the rage at OEM dealerships like Dodge,GM,Ford because they where so much cheaper then replacing the crank it was easier to seal to the customer. The lip load issue was always what the engineers where crying about so it looks like they addressed this 15 years latter!!!LOL

 

[onion]

Yes, the thin "speedy sleeves" are still sold for industrial applications. They're thin enough that the original style seal can be used over them. So thin, in fact, that the sleeve will eventually sag down into the groove that it covers unless you fill the gap with locktite.

Hard to say about the Jeep without looking at it. But if you've replaced the seal twice and you're confident in your work, you'd do well to look the engine over very closely and make sure where the oil is coming from. In pretty much any front engine/RWD application, oil leaks will tend to go down and back for obvious reasons. So given some time, lots of oil leaks end up looking like rear seal leaks- I've dealt with it over and over.

Your best bet is to thoroughly clean all the oil off the engine (a steam cleaner works best if you can get to one), then drive the vehicle a day or so, and check it over closely for any fresh oil.