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My 4.0 leaks from my BRAND NEW RMS. My question is, is it really feasible to replace the RMS with the transmission in the truck? I don’t want to have to drop my trans...again. I know it’s typical for these trucks to leak, but with the time and money I have in it, it is not going to leak for long. I am running a 4.0 and an external slave AX-15. 

 

I’m not planning on replacing my RMS until I need to change the oil, and I will probably change the transmission fluid then too, being that it’s a new trans, but I’m really hoping I can get away with not needing to pull the transmission. 

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you can absolutely change out a 4.0 RMS without dropping the trans. :L:  

 

took me a few tries to get mine to seal properly.  :( 

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39 minutes ago, Pete M said:

you can absolutely change out a 4.0 RMS without dropping the trans. :L:  

 

took me a few tries to get mine to seal properly.  :( 

Thanks. My dad has built a few engines before, but this one just did not take. I’m probably going to go with a Mopar one, if I can. 

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15 minutes ago, 89 MJ said:

Thanks. My dad has built a few engines before, but this one just did not take. I’m probably going to go with a Mopar one, if I can. 

Let us know what techniques work for you guys , I remember being so disappointed after completing the job and having it leak oil still :mad:

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hope its not in backwards. :doh: biggest thing is getting oil pan off. in order to do that on stock lift jeeps, need to disconnect trac bar and possibly upper control arms, shocks, to get axle to droop down far enough to allow you to drop pan and slightly forward to clear the oil pump. be sure to dapple some rtv on the ends when replacing bearing cap    

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Don't forget to check the valve cover gasket, CCV system, and last but certainly not least, the oil drain plug. After I replaced the RMS, 90% of my oil leakage was from a drain plug that just didn't seal anymore. The sealing surface on the plug has a finite number of uses, and will leak eventually.

 

Also, the current Mopar recommendation is to apply an anaerobic sealant (the dealer sells one which is what I use) to this location:

1519128517_rms515.jpg.515f3fc770b1a2d812e8b4ecb1fd237e.jpg

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9 hours ago, MiNi Beast said:

hope its not in backwards. :doh: biggest thing is getting oil pan off. in order to do that on stock lift jeeps, need to disconnect trac bar and possibly upper control arms, shocks, to get axle to droop down far enough to allow you to drop pan and slightly forward to clear the oil pump. be sure to dapple some rtv on the ends when replacing bearing cap    

I know it is not in backwards. I have a little bit of lift, but I have no problem with removal no stuff to fix this dang leak. Thank you!

8 hours ago, Pete M said:

RTV placement is key.  also be patient enough to let the RTV cure before you fire it up.  :L: 

We did put RTV on it and it sat for a few days before we fired it. I think the seal was just no good. Thanks!

2 hours ago, ghetdjc320 said:

Is your PCV working correctly? A plugged system will blow oil out every seal

Yup, everything is working as it should be. Thank you!

1 hour ago, Minuit said:

Don't forget to check the valve cover gasket, CCV system, and last but certainly not least, the oil drain plug. After I replaced the RMS, 90% of my oil leakage was from a drain plug that just didn't seal anymore. The sealing surface on the plug has a finite number of uses, and will leak eventually.

 

Also, the current Mopar recommendation is to apply an anaerobic sealant (the dealer sells one which is what I use) to this location:

1519128517_rms515.jpg.515f3fc770b1a2d812e8b4ecb1fd237e.jpg

Thank you for the tips and diagram. I have been able to trace the leak to the RMS. 

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I'd put the brakes on and do some poking around first.

 

Here's why.

 

REAR MAIN SEAL DIAGNOSIS

 

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. 

 

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44 minutes ago, cruiser54 said:

I'd put the brakes on and do some poking around first.

 

Here's why.

 

REAR MAIN SEAL DIAGNOSIS

 

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. 

 

Thank you. From

our checking, it is coming from the RMS. 

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1 hour ago, JMO413 said:

You can definitely change it without pulling the trans. Only tip I have is use dish soap as lube when you install it. 

Thank you! Never thought of using dish soap. 

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18 minutes ago, 89 MJ said:

Thank you! Never thought of using dish soap. 

I actually got that from nickintime. I have read that from multiple places in the wonderful internet.

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