rear main seal?

[watchamakalit]

I'm pretty certain. Whats everyone elses thoughts? 

 

 

 

For reference the top side is all dry.

 

 

 

[89 MJ]

That looks like a lot of oil for an RMS. I’d check the oil pan gasket first. 

[watchamakalit]

Its too late......

[fiatslug87]

If it was just the oil pan gasket, replacing the RMS is a good idea while you're in there anyway. 

[cruiser54]

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. 

 

[watchamakalit]

10 hours ago, cruiser54 said:

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. 

 

See original post. Only oil on motor is shown on the pan. Pan gasket and rms were both original the way it looked. Old rms was hard as porcelain. Either way the both needed and got done. Hopefully no more leaks.

[jamcomanche]

You have oil on your starter. Looks like I'm too late and It may not be the same issue obviously, but my 87 has a steady oil leak that is dripping in the same location as yours.  I degreased everything and have been monitoring it for a few days.  The first day I noticed that oil was dripping down the starter, just like yours.  I was able to trace the leak up to the distributor.  I'm ordering a distributor mount gasket today. 

[watchamakalit]

7 hours ago, jamcomanche said:

You have oil on your starter. Looks like I'm too late and It may not be the same issue obviously, but my 87 has a steady oil leak that is dripping in the same location as yours.  I degreased everything and have been monitoring it for a few days.  The first day I noticed that oil was dripping down the starter, just like yours.  I was able to trace the leak up to the distributor.  I'm ordering a distributor mount gasket today. 

The only oil gaskets I have left to change are the dizzy and oil filter adapter. So far no leaks from either. It had taken about 3 cases of degreaser to get to where I am over the years but am gaining on the leaks.  The pan gasket was for sure leaking and the rear main was rock hard and had to be leaking. So no loss either way. It has already been changed but the truck is out of commission for other problems.

[jamcomanche]

2 hours ago, watchamakalit said:

The only oil gaskets I have left to change are the dizzy and oil filter adapter. So far no leaks from either. It had taken about 3 cases of degreaser to get to where I am over the years but am gaining on the leaks.  The pan gasket was for sure leaking and the rear main was rock hard and had to be leaking. So no loss either way. It has already been changed but the truck is out of commission for other problems.

How hard was it getting the RMS out?  Did you do it without removing the crank and do the cut/feed/rtv trick?

[watchamakalit]

I have done a few over the years. I simply pull the rear main and push the seal out. Sometimes it takes a little persuasion to get it atarted moving but should slide out fairly easy.