Pentastar 3.6L rear main seal cover plate leak

wwillson

Staff member
Joined
Aug 20, 2003
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Naperville, IL
My friend had a 2017 Jeep up on the lift when I stopped in the other day. The rear main seal cover plate was leaking and causing a small puddle of oil on the owner's garage floor every morning. The job is about $1500, mostly in labor and requires the exhaust and trans to be removed. I had no idea rear mains are sometimes in a cover plate that bolts to the back of the engine. I was also surprised to see some varnish on the wet side of the cover plate with only 50,000 miles on the clock - you can see where I rubbed the varnish off with my finger. The yellow circle indicates where the plate was leaking.

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Joined
Jun 3, 2005
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Santa Barbara, CA
My friend had a 2017 Jeep up on the lift when I stopped in the other day. The rear main seal cover plate was leaking and causing a small puddle of oil on the owner's garage floor every morning. The job is about $1500, mostly in labor and requires the exhaust and trans to be removed. I had no idea rear mains are sometimes in a cover plate that bolts to the back of the engine. I was also surprised to see some varnish on the wet side of the cover plate with only 50,000 miles on the clock - you can see where I rubbed the varnish off with my finger. The yellow circle indicates where the plate was leaking.

All of the Ford modular based engines have a plate as well as the GM LSx engines. Its a nice setup I think.
 

AZjeff

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Jan 14, 2011
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northern Az where the Antelope play
How much does that plate cost? It's wrong to have to spend $1500 to replace a $50 part on any vehicle. :mad: Our Xterra has a leaking RMS and I just can't spend $1000 to replace a $20 seal on a 20 YO 155k mile vehicle.
 
Joined
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WA
How much does that plate cost? It's wrong to have to spend $1500 to replace a $50 part on any vehicle. :mad: Our Xterra has a leaking RMS and I just can't spend $1000 to replace a $20 seal on a 20 YO 155k mile vehicle.
It's the perimeter O ring & actual seal replaced. The labor is in the trans drop.
The aluminum plate thing has been around since, oh, 1980s. Think Europeans started it. If you want to blame someone.
 
Joined
Apr 7, 2010
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Detroit
Replacing a RMS is such a breeze on a RWD (not awd/4wd). I can pull the trans on my 1991 Toyota Van in 2 hours.

Disconnect driveshaft, slave cylinder, starter motor, bell housing bolts, transmission shifter lines, and drop.
 
Joined
Apr 7, 2010
Messages
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Detroit
It's the perimeter O ring & actual seal replaced. The labor is in the trans drop.
The aluminum plate thing has been around since, oh, 1980s. Think Europeans started it. If you want to blame someone.
My Toyota is exactly the same way!
 

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I remember doing an RMS on my S10. Drop driveshaft, lift engine as much as I could, so as to drop oil pan. Then remove main bearing cap so as to get to the seal. No fun. Guessing that larger RWD vehicles had better access to the RMS than that S10?
 

D60

Joined
Nov 6, 2017
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Colo
Yep, as mentioned Toyota does exactly this. The problem is that several threads on bigger Toyota forums tell you not to disturb the plate if doing the RMS because you're just creating extra work for yourself and opening a can of worms.

In reality this logic is flawed -- there's a good chance it's the RTV leaking and if you ONLY replace the seal you're only doing half the job. Pulling the plate -- at least on Toyota 3.0/3.4 -- is not difficult and does not run the risk of creating other problems if you're just conscientious

I learned the hard way but in the future when I'm already that deep in I will always re-seal the plate and replace the RMS
 
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