Rear Main Seal

ChuMaDD

ChuMaDD

Meh
Joined
Aug 6, 2012
Messages
613
Well it has been almost 6 months since I had the nv4500 off my truck to put in the DD clutch I had purchased. I also replaced the rear main while I was back there, but as I was driving to work today I smelled something like burning oil. As soon as I got to work I looked underneath the truck, I couldn't believe it but there was oil slung all over the place. It seems to be coming out of the bell housing so I think it is safe to assume the rear main went. Now I need to dig into it and find out why... I have never had this happen before to me with nothing else being broken so you can imagine how happy I am...:bang:bang:bang

Now I have changed the oil about a month ago just like I normally do at 4000 miles with amsoil. Truck has no performance issues that I could put my finger on. Any ideas as to what could of caused this without effecting performance?

I hope I can salvage the clutch will try and post some pictures if I remember with what I find. Any tips on what to do to try and save the clutch from further damage from oil contamination other than removing it from the trans and wiping it clean?
 
Improper install is the typical reason for premature failure.
 
Make sure it is the rear main leaking for sure. I've had the soft plug on the oil pressure galley leak and run down and make it look like the rear main is leaking. The cam bore plug can also leak. Try to pin point it down if you have to tear it back again, so you don't have to do it a third time.
 
Good points.

As to the seal itself, the most common installation mistake is that the seal and the crankshaft must be bone dry. No oil or grease.
 
I will look in those areas as well, the seal went on bone dry when I installed it and used the installation tools as well that came with the seal itself. Had too much going on today to tear into it so it is still sitting in the corner of the shop
 
I could nearly swear to it but stock cummins rear mains for like 6bt's call for a mild detergent soap as a lubricant for installation. I could be totally wrong but I tink I remember this.
 
I'm pretty sure they say install dry right on the lip of the seal. I always install them dry though.

Also another thing to check is to make sure there aren't any grooves worn into the surface of the crank from the old seal. This will cause premature failure too.
 
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Like dieselwrencher said check the seal grove. If it has one then buy the sleeved seal. Amsoil Will find leaks. Doesn't help that these engines have a terrible front/rear main seal design.
 
RyanH said:
Like dieselwrencher said check the seal grove. If it has one then buy the sleeved seal. Amsoil Will find leaks. Doesn't help that these engines have a terrible front/rear main seal design.
Click to expand...

Yea it is a love hate relationship with Amsoil because of that. But iirc I don't remember anything drastic as far as wear on the crank.

Will have to wait till next week to tear into her though due to work keeping me busier than usual.
 
Rick James said:
I could nearly swear to it but stock cummins rear mains for like 6bt's call for a mild detergent soap as a lubricant for installation. I could be totally wrong but I tink I remember this.
Click to expand...

They recommend that for installing the seal into the seal housing. The actual seal face goes on the crank dry.
 
Little update, truck is back up and leak free. There was a very minute metal burr (that was from the previous owner) that I must of missed on the housing that caused the leak in the rear main.
 
I'm pulling off the flexplate and bellhousing adapter today to replace a suspected rear main leak, basically I need to inspect the cam plug and oil pressure soft plug as well?

Tips? Other common leak areas? I've never been back there with the adapter plate off before, but I developed a nasty leak in that area.

Did I make a mistake getting a Felpro replacement?
 
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I pulled the flexplate and even though I saw some oil it didn't seem to be relative to what I was seeing on the ground. Pulled the adapter and bam, a little river of oil running down from the rear cam plug.

I've got some searching to do, not sure whether to replace it or....

[ame="http://www.youtube.com/watch?v=RUSFM5Rjbws"]adam.just.tap.it.in - YouTube[/ame]
 
I would check to make sure your cam gear has not walked, pushing back on the plug.
 
I just read that in another thread. That'll make this fix a little more involved, lol. Time to grab a snack and head back out.

The cam plug and oring are a week away according to the local Cummins store. Plug: 3900687 - $4.66, Oring: 3926047 - $3.38.
 
I'm borrowing a scope to check the cam gear. As much as I need my truck back on the road, I do have a Hamilton 181/210 that's been laying around for a while...

Does anyone know if you have to get a new oring and plug for a fix or perhaps just pull and reinstall?

A picture for inquiring minds:
attachment.php
 
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Bersaglieri said:
I'm borrowing a scope to check the cam gear. As much as I need my truck back on the road, I do have a Hamilton 181/210 that's been laying around for a while...

Does anyone know if you have to get a new oring and plug for a fix or perhaps just pull and reinstall?

A picture for inquiring minds:
attachment.php
Click to expand...

My cam gear walked and pushed the plug out, I was in a hurry and didn't have a new plug so I put a piece of rubber on top of the old plug so the bellhousing adapter would hold it in place. I also rtv'ed around the plug and sealed the block to the adapter plate. Worked for me.

If its a stock cam with no retainer I bet that gear walked off some. Would be a great time to install the hamilton cam and retainer...:D
 
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