My Rear Main Engine Seal Went Bad After Only A Year in My M1009 6.2L

[jplace1011]

In March of 2021 I had the Rear Main Engine Seal Replaced in my CUCV M1009 6.2L. It’s already starting to leak again. Is this normal? If not, any ideas what could have gone wrong? What is the Best Seal I can use this time around?

I recently had the Valve Cover Gaskets Replaced, as well as the Harmonic Balancer and Seal. I suspect that has nothing to do with it, but still want to mention it.

Thank you in advance for any input, I greatly appreciate it.


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[cucvrus]

I am going to say the person that changed it aligned the seal seams with the main cap. I seen it many times. Getting the rear seal in can be a bear at times. I have had to loosen all the main bearings on a few just to get the crank to drop a bit. Others I oiled and slipped right in. Getting it in the correct way is also key. i found them in backwards on one side of the seal. Good Luck. Do it right. Do it yourself.

 

[jplace1011]

I am going to say the person that changed it aligned the seal seams with the main cap. I seen it many times. Getting the rear seal in can be a bear at times. I have had to loosen all the main bearings on a few just to get the crank to drop a bit. Others I oiled and slipped right in. Getting it in the correct way is also key. i fond them i backwards on one side of the seal. Good Luck. Do it right. Do it yourself.

@cucvrus I have been suspecting/wondering if they did it wrong. This may be a stupid question, I had the Front & Rear Driveshafts replaced. Is it possible they could have disturbed the Rear Main Seal during all of that?


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[nyoffroad]

@cucvrus I have been suspecting/wondering if they did it wrong. This may be a stupid question, I had the Front & Rear Driveshafts replaced. Is it possible they could have disturbed the Rear Main Seal during all of that?


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I don't see how the drive shafts could have effected the rear main, someone would've had to work REAL hard to do that! It's kinda like blaming your oil leak on the guy that recovered your seat cushion.

 

[jplace1011]

I don't see how the drive shafts could have effected the rear main, someone would've had to work REAL hard to do that! It's kinda like blaming your oil leak on the guy that recovered your seat cushion.

So It Was a stupid question!


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[Squibbly]

I second @cucvrus. People put the seals in, in the 9 & 3 position all the time. I even see them do it wrong in instructional videos on youtube. You have to offset them.

You sure it's the rear main, and not just something leaking down from the valve covers or someplace else?

Pull the inspection cover off, clean all the oil off real well, spray some desitin foot itch spray on it (including ABOVE where you *think* it's coming from), and go drive it around. When you get back look for the highest spot you see the stream of oil come from.

 

[jplace1011]

I second @cucvrus. People put the seals in, in the 9 & 3 position all the time. I even see them do it wrong in instructional videos on youtube. You have to offset them.

You sure it's the rear main, and not just something leaking down from the valve covers or someplace else?

Pull the inspection cover off, clean all the oil off real well, spray some desitin foot itch spray on it (including ABOVE where you *think* it's coming from), and go drive it around. When you get back look for the highest spot you see the stream of oil come from.

That’s a great idea buddy! I just had the Valve Cover Gaskets replaced. We checked them, but they aren’t leaking.


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[jplace1011]

That’s a great idea buddy! I just had the Valve Cover Gaskets replaced. We checked them, but they aren’t leaking.


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One thought I’m having. When taking apart the current Rear Main Seal, can’t I check it to see how it’s oriented and if it’s in backwards? If so, that could answer the question as to why it’s leaking?


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[Squibbly]

One thought I’m having. When taking apart the current Rear Main Seal, can’t I check it to see how it’s oriented and if it’s in backwards? If so, that could answer the question as to why it’s leaking?


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Do you have a torque wrench? If so, yes you can.
You’ll need some RTV sealant and some assembly lube for the bearing when you put the cap back on (the same orientation it came off), and depending on your oil pan a new gasket and sealant. You will obviously need new oil unless you just changed it and you’re putting it in a new container (not recommended).

Torque specs should be in the manual.


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[cucvrus]

I would check everything up top. I would pull vacuum pump and use some sealer on the mounting surface. I would inspect the vacuum pump closely. I had one leak up the shaft. Only one but if it happened to me it could happen to someone else. Check your valley under the injection pump. But putting a rear main seal in is a job that you must do correctly. No half fast almost got it or good enough. There is enough of that work going on everywhere that I could work the rest of my life repairing. I quit doing jobs that people tried to fix and failed. If it is failing after they done it I have no idea how or why it failed and am not interested in getting in on the blame game. and as far as warranty goes on 40 year old trucks. That is a NO GO. I fix it if it works at the moment of repair and a similar condition occurs a week later. I say you are getting the wallet out. I can't warranty anything. I never got warranties on any CUCV I ever bought. Never. Good Luck. Follow instructions to the letter and it can be done.