Advise on rear main seal

[DJM/78]

I need some advise on a R.M.S for a 92 4.0 5 sp 4x4 . The leak is at the flex plate and loses about a 1/2 quart every three

weeks . I am replacing the seal , but what else should I do or look for while I'm in there ? :???:

[comanche09]

I've read its best to use an OEM RMS. I used aftermarket and have had no leaks so far.

 

While you've got the pan off, you could clean it up and repaint the outside if it needs it (of course clean out any slugde from the pan). I just replaced mine with a nice one out of the junkyard, original was too far gone (rusty).

 

Check the torque on the Main Bearing Cap and Connecting Rod bolts. -Consider replacing same bearings if you have lower than normal oil pressure (their not that expensive).

 

Consider replacing the oil pump.

 

Take a look at your timing chain and check for excessive slack.

 

I recommend using the one piece Felpro pan gasket.

 

Hope that helps!

 

PS: I removed the entire front axle when I did mine (swapped in a D30 while I was at it) Depending on if you are lifted or not, you may have to unbolt some suspension/steering parts to allow the axle to droop enough to clear the oil pan out.

[RLCollins]

how many miles on the engine?

I used an aftermarket RMS with no problems. Make sure to lubricate the seal before installing it. oil the inside of the seal, and dishsoap on the outside to help it slide around the crankshaft. If it is going to sit for a while then use grease instead of oil.

Make sure to add a little RTV Sealant to the corners, where the rear and front main caps meet the engine block to insure a good seal :D

I also agree with a one piece FEL-PRO oil pan gasket. The one I used was OS 34308 R for a 4.0 I-6

Use a torque wrench to avoid errors. There are two different size bolts in the oil pan. The 1/4 X 20 torque to 84 inch pounds and the 5/16 X 18 132 inch pounds. I also replace the oil pump which I read on one of the blogs, for high mileage engines. They recommended a Melling Mel-M167HVS pump made in AMERICA which I installed. My Harmonic balancer rubber clutch was separating so I replace it along with the water pump and timing chain which was loose. Have fun :chillin:

[DJM/78]

Great info , I feel a lot better about the project !!!!! I like Fel-pro too :D

I have used them in the past. :clapping:

I'll replace the oil pump & the timing belt as well. As my truck just went over 200k

Thanx

 

Dave M.

[Geonovast]

You don't have a timing belt, it's a chain.

 

If you've got the original oil pan gasket, you're going to have a hell of a time scraping it off the block and pan.

[Oizarod115]

inspect carefully for scoring where the RMS rides on the crankshaft... any wear in the metal will cause it to not seal no matter what you do.

 

also, try taking cardboard and drawing the oil pan and punching the bolts for it into the cardboard to keep up with where they go... there's alot of em. :idea:

[comanche09]

If you've got the original oil pan gasket, you're going to have a hell of a time scraping it off the block and pan.

 

I got lucky with this as most of it came off with the pan (another reason I replaced it). To get the original gasket off the block, I used aerosol spray gasket remover (be careful with this stuff, very toxic, eats paint/skin, causes cancer etc.) and a flat razor blade.

 

I used small zip ties, strategically placed, to hold the gasket to the pan for installation.

[Eagle]

inspect carefully for scoring where the RMS rides on the crankshaft... any wear in the metal will cause it to not seal no matter what you do.

Somebody (FelPro?) makes a replacement RMS with a dual-lip wiper to address exactly this problem. If you see even a fait line on the crank surface that won't clean up, get the seal with the dual lips.

[DJM/78]

Thats what I need , I want to do everything right the first time. I'm not that great as a mechanic ,don't want to do it all again.

 

I learn as I go and now I'm like G.I Joe :yes:

[Pete M]

Whatever you do. make sure you have 2 of everything you need and don't be in a hurry to get your truck back on the road. :thumbsup: i.e. allow plenty of downtime for this, as plenty can go wrong. I dropped the pan 4 or 5 times for the rms in my 88. :fs1:

[aemsee]

You guys forgot one of the most important things. Drain the oil from the pan first!! :D Seriously, drain it and let the engine sit as long as posible before dropping the pan. Will help to alleviate some of the oil dripping in your face. And wear safety glasses if ya got 'em.

 

PS. a quart every three weeks isn't a massive amount for a RMS. Be sure it isn't your VCG and oil just running down the back of the motor.

[Pete M]

x2 on triple checking the valve cover.

 

And I'd add ear plugs to the list. nothing like oil dripping in your ear to make you, uh, wish you had listened to me. :D

[DJM/78]

Yeah , I'm going to inspect the valve cover this weekend. I may have to deal with the leak for a while , because I'm just set

on doing everything while I'm in there. Oil pump, fel-pro seal, fel -pro gasket , timing chain and water pump .

 

I'll probably replace the bearings , serpentine belt and all the radiator and heater hoses as I read the thread on heater hose problems

 

Great info , I didn't even think of ear plugs!!!!!

thanx

 

: Dave M.

[mjeff87]

when you start the teardown, take the new RMS and place both halves in a shallow pan and submerge them in new oil. Let them soak in it while you rip it all apart.

 

To install the new upper half (after you cuss and moan getting the old one out), start one end of it in the upper bearing half and rotate the crank slowly via the harmonic balancer bolt ( a second set of hands helps with this) while you feed the new seal in and around. Make sure it's centered, then install the lower half in the bottom bearing cap and apply a small dab of RTV outboard of the rear seal surface. Let it tack for about 5 minutes, then install the bearing cap.

 

Jeff