Oil Leak
10-15-2022, 10:41 AM
#1
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Year: 1998
Model: Cherokee (XJ)
Engine: 4.0l inline 6
Oil Leak
I found oil under my jeep and when I looked there was oil on the bottom of the transmission pan and the front dif. It seems to leak when I park the jeep after driving. I'm thinking rear main seal . . . Anyone have any other thoughts?
10-15-2022, 02:08 PM
#4
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
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.
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10-15-2022, 05:15 PM
#5
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Year: 1998
Model: Cherokee (XJ)
Engine: 4.0l inline 6
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.
10-15-2022, 06:16 PM
#6
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Year: 1990
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It's a pain in the *** to replace the rear main seal compared to a valve cover gasket!! Use Felpro Blue gasket only.
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10-15-2022, 09:57 PM
#8
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You read my complete post didn't you? #4.
10-16-2022, 05:26 AM
#9
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I would only change the rear main seal as an absolute last resort, as its a lot of work, can still give issues, and all other oil leaks should be fixed first
the oil filter seals and tappet cover gasket are known leak areas, and are easy to fix. The pan seal and front crank seal can also leak
10-16-2022, 12:10 PM
#10
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Year: 1998
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Yeah, did I miss something?
I actually did degrease the top of the engine yesterday. I'll need to do the bottom soon. It does appear that I have seepage from the valve cover gasket (is that the same as the tappet cover gasket?)
In my opinion, one should clean the engine very well with degreaser and rags, that way you can see where the oil leak is coming from
I would only change the rear main seal as an absolute last resort, as its a lot of work, can still give issues, and all other oil leaks should be fixed first
the oil filter seals and tappet cover gasket are known leak areas, and are easy to fix. The pan seal and front crank seal can also leak
I would only change the rear main seal as an absolute last resort, as its a lot of work, can still give issues, and all other oil leaks should be fixed first
the oil filter seals and tappet cover gasket are known leak areas, and are easy to fix. The pan seal and front crank seal can also leak
11-10-2022, 06:09 PM
#11
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Year: 1998
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I replaced the valve cover gasket and despite not having one bolt due to the PO breaking it off in the block, most of my oil leaks are gone. I think its still leaking at the oil filter adapter, but it's certainly better than it was. I used the fel-pro blue rubber gasket because everyone recommended it, and it seems to work well.
12-15-2022, 11:53 AM
#12
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I wish I would’ve seen this a couple days ago. I got my transmission dropped about to do RMS and oil pan gasket. I’m gonna be pissed if I get it buttoned back up and still leaking.
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cruiser54 (12-15-2022)
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