Jonliddle370

hey guys so i bought a 1992 cherokee 2 door laredo and it needs a lot of work. Im looking to replace the RMS, oil pan gasket and valve cover gasket on a 215000 mile motor but no one seems to want to do it (RMS specifically). I have an oil leak that needs to be fixed. any suggestions on what to do? one guy said he doesnt recomend RMS replacement on anything over 100k miles, but im trying too squeeze out as much life out of this motor that I can. The motor runs great.

RocketMouse

If you're careful... doing the RMS yourself isn't that bad. But before you go and replace it... make sure that the RMS is ACTUALLY what is leaking. The 4.0's sit in the bay just slightly nose up... so check things up top first because oil will migrate downhill right to the same point underneath that would make you think it's the RMS.
Check around the back of your valve cover and anything else in that area. If it is the RMS...then as long as you take your time and be careful, it is totally a DIY... and even easier if you have a lift b/c you need to take the pan off.

Jonliddle370

thanks for the quick reply!

cruiser54

Do the valve cover gasket first........CRUISER'S MOSTLY RENIX TIPS

REAR MAIN SEAL DIAGNOSIS

OCTOBER 31, 2015 SALAD 3 COMMENTS

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.

Jonliddle370

Thank you so much this helps a lot!

lawsoncl

On the plus side, you just found a mechanic to avoid. X2 on fixing the other usual leaks like the valve cover and oil filter adapter first, before you assume it''s the RMS.