Rear main oil leak
09-10-2021, 04:08 PM
#1
Newbie
Thread Starter
Join Date: Jul 2016
Posts: 6
Likes: 0
Received 0 Likes
on
0 Posts
Model: Cherokee
Rear main oil leak
Took my jeep 4.0 to smog shop other day an while it was on Dino it peed oil all over the guys floor. It does not leak when sitting still and running only under load. Also it just drips it doesn't sling it around. Main or pan?
09-10-2021, 07:55 PM
#2
CF Veteran
Join Date: Dec 2017
Posts: 3,984
Received 1,106 Likes
on
885 Posts
Year: 1989
Model: Comanche (MJ)
Engine: 4.0
Start up top. If the back of the block is wet, suspect the valve cover. Oil filter adapter leaks are also common and tends to run towards the back and get the top of the starter.
09-10-2021, 08:15 PM
#3
Member
Join Date: Nov 2009
Location: Vernon B.C. Can.
Posts: 214
Likes: 0
Received 26 Likes
on
16 Posts
Year: 89
Model: Cherokee
I had the same thoughts when I first got my jeep ,is was the oil filter adapter O- rings . 50 cents for O-rings
Rear dr. side valve cover can leak as on mine is hard to get a snug fit, need a better wrench adapter I guess
Rear dr. side valve cover can leak as on mine is hard to get a snug fit, need a better wrench adapter I guess
Last edited by blazer 2008; 09-10-2021 at 08:17 PM.
09-10-2021, 08:56 PM
#4
CF Veteran
Join Date: May 2012
Location: Lost in the wilds of Virginia
Posts: 7,964
Received 954 Likes
on
769 Posts
Year: 1998 Classic (I'll get it running soon....) and 02 Grand
Model: Cherokee (XJ)
Engine: 4.0
Yep. A lot of rear seals have been replaced when they didn't need to be.
09-11-2021, 08:18 AM
#5
::CF Moderator::
Join Date: Aug 2011
Location: Prescott, Az
Posts: 43,971
Received 1,555 Likes
on
1,261 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Here ya go.CRUISER'S MOSTLY RENIX TIPS
I’d be looking up ABOVE first, and VERIFYING the source of the oil leak YOURSELF.
Everybody, who doesn’t own or have to pay for or perform your vehicle repairs, loves to poke their noggin UNDER the Jeep and come out bearing the false bad news that your RMS is leaking. Many mechanics, friends, and good old Uncle Bob seem to enjoy telling you it’s the rear main seal. Has a catastrophic ring to it, doesn’t it?
A simple leak at the back of the valve cover or other source could produce the same symptoms. You don’t need to be a mechanic to figure this out. If you have good eyesight and a dim flashlight, you’re good to go on your own. Don’t jump on the RMS/oil pan gasket bandwagon right off the bat.
Almost any oil leak on your 4.0 is gonna drip from the RMS area for two simple reasons:
First off, the engine sits nose-up and any oil will run back to the RMS area.
Secondly, the RMS area is also the lowest point on the engine. Simple physics and the old plumber’s adage apply here: “Crap flows downhill”.
Valve cover gasket, oil pressure sending unit, oil filter adapter seals and distributor gasket, in that order, have to be eliminated as possibilities first. A little tip here. Rather than use a dizzy gasket, use an o ring instead. NAPA #727-2024. Tips 12 and 13 will help you get your distributor back in place correctly.
REAR MAIN SEAL DIAGNOSIS
OCTOBER 31, 2015 SALAD 3 COMMENTSI’d be looking up ABOVE first, and VERIFYING the source of the oil leak YOURSELF.
Everybody, who doesn’t own or have to pay for or perform your vehicle repairs, loves to poke their noggin UNDER the Jeep and come out bearing the false bad news that your RMS is leaking. Many mechanics, friends, and good old Uncle Bob seem to enjoy telling you it’s the rear main seal. Has a catastrophic ring to it, doesn’t it?
A simple leak at the back of the valve cover or other source could produce the same symptoms. You don’t need to be a mechanic to figure this out. If you have good eyesight and a dim flashlight, you’re good to go on your own. Don’t jump on the RMS/oil pan gasket bandwagon right off the bat.
Almost any oil leak on your 4.0 is gonna drip from the RMS area for two simple reasons:
First off, the engine sits nose-up and any oil will run back to the RMS area.
Secondly, the RMS area is also the lowest point on the engine. Simple physics and the old plumber’s adage apply here: “Crap flows downhill”.
Valve cover gasket, oil pressure sending unit, oil filter adapter seals and distributor gasket, in that order, have to be eliminated as possibilities first. A little tip here. Rather than use a dizzy gasket, use an o ring instead. NAPA #727-2024. Tips 12 and 13 will help you get your distributor back in place correctly.
The following 2 users liked this post by cruiser54:
BlueRidgeMark (09-11-2021),
richartdana44 (12-23-2023)
Thread
Thread Starter
Forum
Replies
Last Post
Remus Redbone
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
3
07-20-2017 12:12 PM
trailshredder
Stock Grand Cherokee Tech. All ZJ/WJ/WK Non-modified/stock questions go here!
1
08-15-2013 09:20 PM
Camoninja
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
5
06-05-2011 10:55 PM
jd4x426
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
8
05-16-2009 06:50 PM
axeld20
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
14
07-21-2008 08:26 PM
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)