Wanted to get some opinions on what I may have. Based on what I have read on this forum, it looks like I have a rear main seal leak. This started just after labor day weekend. Only seems to drip while driving around because it's dripping several drops as soon as I pull in anywhere, but once its done dripping it wont leak any more.

Seems to be leaking from the rear pan and the front of the transmission. I checked the drain tube and the surrounding area, and that's not it. I removed the inspection plate on the transmission and can see black motor oil collecting in there. Here are some pics.

What do you guys think?

 

It is possible that the rear main is leaking but I'd almost put money on the table that it's the cam seal causing the drip. Either way the trans has to come out. Went through the same scenario about 5yrs ago and again 2 weeks ago when I installed a new clutch.

 

Well, since the transmission has to come out, what other seal should I go ahead replace since I'm in there? Stupid question, where is the camshaft seal?

I'm undecided if this is something I want to try and do myself with a help of a friend or just have a shop do it. I have done front end work and am mechanically inclined, but have never removed or installed a transmission. I mean, I'm no master mechanic but can get around stuff pretty well. How difficult of a job is this on a 2wd? What do i need to know?

 

2wd makes it easier to pull the trans. Once it's removed there is an aluminum plate bolted to the back of the block. Remove the bolts holding it on and when you pull it off just flip it around and you will see the $4 cam seal....it's a square faced o-ring. As for the main seal...there is another plate that needs to be removed in order to get it removed and re-installed. May be able to do the main seal with the plate in place but for me it was easier to remove it.

 

Johnny77..I had almost the same problem. Turned out to be the bolt was loose on the center plate on the injector pump. It would allow fuel/oil to collect in the same area as yours (except under inspection plate??) You can only get just a few turns on the bolt. It holes on a round plastic plate on the IP...thanks

 

Justin, thanks for your input on this.

Rushman, I don't see the leak coming from further up the block and it's definitely motor oil. I wish it were something else and I don't have to get the transmission pulled to fix it. But I will check the bolt you are talking about just in case. Rushman, I dont see the leak coming from further up the block and it's definatly

 

Mine would drip down and the fan would blow it to the back. At the lube shop they thought it was a rear main seal, but at the diesel shop they went straight to the bolt and leak stopped. Is your's a 06 5.9? I dont think you list type of truck...thanks

 

Dropped my truck off at the shop yesterday afternoon to have the rear main seal replaced.

 

I have a 2007 with the 5.9 and its a 2wd. I assume that the setup between the 06 and 07 are the same. I can get to this bolt from the top of the engine or the bottom?

Justin, called Cummins here in town and asked them about the camshaft seal, they couldn't help me. They gave me the part number for the Front camshaft seal 3937111. But he couldn't figure out what the seal was that went in the back with or near the rear main. Is there something else that it's called?

 

The tech got to it from the top. He used a 3/8 drive and socket and turned it a little short of one turn. He stated that there was very few threads on this bolt. I didnt get a good look at it, but it looked like it was in the center of a round plastic disc. Mine is a CP3-IP. I want to say it had some fuel in it but I have never been able to get the few spots off my cement drive way. So I think it was mostly oil. The lube shop did tell me the pump was wet, but never tried to tighten the bolt...dought they new to. Tech said he had seen this several times.

JJ

 

Johnny77....Cummins can tell you every part on the engine if you gave them the S/N. The cam seal is just an square o-ring that sits in a groove on the engine side of the aluminum plate bolted to the back of the block. They are very prone to leaking. They're less than $4.

 

Justin, got a hold of someone that was more helpful than the last at Cummins. They gave me P/N: 3947328 for that Camshaft seal you mentioned, it's $2.69

JJ, thanks for the info. It's worth a check at least. But I don't think that would be my problem. Doesn't explain why I have oil inside the transmission when i removed the inspection plate. But you never know, stranger things have happend.

 

Yea, the cam seal came up with my leak also. The tech was explaining that if it was the source of the leak, he would have to remove the radiator and alot of additional stuff and added cost. That was just a moment before he put the wrench on the bolt. It was a great relief when the leak stopped. I dont let anyone work on my truck unless I check it out on this forum first....Good Luck!!

 

Johnny 77, should you decide to dig into this yourself this might help little.

https://www.dieseltruckresource.com/...y-t304887.html

 

Rick, good post on the rear main. To the OP.....once you pull the plate that was pictured in TRads post you'll see the little seal I'm talking about.