Rear Main Seal Question

Hey Group,
I've got a 91 Jeep Cherokee with a 4.0 engine. Can anyone tell me if this
is a one piece knock-in seal or is it the old two piece type where you have
to drop the pan and the last rear main cap. Just trying to plan my weekend
out.
Thanks,
Charles

2 piece.

But, way over 50% of the 'rear main' leaks turn out to be just a valve
cover leak. The engine is tilted and when the valve cover leaks it runs
right straight down the back imitating a rear main seal leak.

To check, get the engine running and wipe a clean rag behind the head,
if you find oil, you have likely found the main leak.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

Ervin Charles wrote:
>
> Hey Group,
> I've got a 91 Jeep Cherokee with a 4.0 engine. Can anyone tell me if this
> is a one piece knock-in seal or is it the old two piece type where you have
> to drop the pan and the last rear main cap. Just trying to plan my weekend
> out.
> Thanks,
> Charles

On Thu, 16 Dec 2004 17:05:37 -0600, Ervin Charles wrote:

> Hey Group,
> I've got a 91 Jeep Cherokee with a 4.0 engine. Can anyone tell me if this
> is a one piece knock-in seal or is it the old two piece type where you have
> to drop the pan and the last rear main cap. Just trying to plan my weekend
> out.
> Thanks,
> Charles

Two piece, drop the pan & rear main cap. I replaced my rear main seal a
couple of months ago. Wasn't as bad a job as I expected.
88 Cherokee

Rick

It'll be the valve cover gasket, like Mike already attested to,
whip it off between the rear of the head and cowl, take it for a drive
and whip it again, you'll find fresh oil. If you still want to change
the seal, just for the halibut: http://www.neow.org/rms1.html
God Bless America, ßill O|||||||O
http://www.billhughes.com/

Ervin Charles wrote:
>
> Hey Group,
> I've got a 91 Jeep Cherokee with a 4.0 engine. Can anyone tell me if this
> is a one piece knock-in seal or is it the old two piece type where you have
> to drop the pan and the last rear main cap. Just trying to plan my weekend
> out.
> Thanks,
> Charles

I sure wish you guys were right about the valve cover gasket, but I replaced
it a couple of months ago. This engine has 188,000 miles on it and it's
definitely the rear main...flowing like the Exxon Valdez. Do I absolutely
have to pull the tranny or can I snake it in with the trans in place? Thanks
for your replies!
Charles

wipe

The only advice of my mothers that I actually follow!


"L.W. ("ßill") Hughes III" > wrote in message
...
> wipe

It's a two piece seal. It is relatively easy to replace, but seldom fails.

The actual problem is most likely the valve cover gasket. Would you like to
know how I know? I hope not.

The engine is raised on the front. Oil is pumped to the top, and flows down
the pushrods back to the crankcase to start over again. While the oil is
flowing down, it also flows to the back. The gasket likes to break in the
back. The gasket is about 1/4" thick. The hole that results when the gasket
breaks is however much the gasket shrinks wneh it breaks x 1/4" (or the
actual thickness of the gasket). Oil flows out this hole, runs down the back
of the motor and off the bottom of the bellhousing. It looks just like a
rear main. Pull the valve cover first.





"Ervin Charles" > wrote in message
...
> Hey Group,
> I've got a 91 Jeep Cherokee with a 4.0 engine. Can anyone tell me if this
> is a one piece knock-in seal or is it the old two piece type where you
> have to drop the pan and the last rear main cap. Just trying to plan my
> weekend out.
> Thanks,
> Charles
>

> It's a two piece seal. It is relatively easy to replace, but seldom fails.

Is the 304 the same? 2 piece?

--
_____________________
HomeBrewer
76-81-85CJ7
http://85cj7.blogspot.com/
All in one Jeep

"HomeBrewer" > wrote in message
...
>> It's a two piece seal. It is relatively easy to replace, but seldom
>> fails.
>
> Is the 304 the same? 2 piece?
>


The rear main seal consists of a two-piece neoprene single lip seal. Correct
installation of the seal is required for leak-free engine operation.

Drain the oil
Remove starter motor
Remove pan
Remove pan side gaskets
Remove all sludge and throughly clean gasket surfaces
Remove rear main bearing cap
Remove and discard lower seal
Clean bearing cal throroughly
Loosen remaining bearing caps
Use brass drift and hammer to remove upper half of seal.


This is from my FSM for 1981 Jeep V8 engines. It seems to apply to both the
304 and the 360.