Engine/Transmission (1994 - 1998) Rear main seal replacement

[edgeman]

I plan on putting a new clutch in my 98,12 valve, on the Thanksgiving weekend. while I have the trany out I plan on changing the rear main seal, since its leaking quite a bit. I have not done this before, and im hopeing that some of you have and can give me a few pointers. Thanks in advance.

 

[SRadke]

Drill a small hole in the perimeter of the seal and insert a screw half way.
Grab the screw head with a slide hammer of pair of vice grips and tap/pull it out.
Clean up perimiter and crank surfaces.
Tap new seal in using Cummins install tool. (buy the $50 kit, comes with the tool)

Takes about 15 minutes

-Scott

 

[TBartlett1]

I've replaced mine 3 times, the 1st & 2nd time I did as SRadke mentioned and they both started to leak prematurely. It was also difficult to get it to slide over the crankshaft as I installed it into the seal retainer.

I later discovered my seal failed prematurely because it was not aligned to the crankshaft.



The third time I removed the closure plate which allowed me to properly press the seal into the retainer.



I also removed the gasket between the retainer and the oil pan which allowed the seal to align itself to the crankshaft; I then carefully tightened the screws holding the retainer to the block.

To seal the gap between the closure plate and the oil pan I forced silicone into the space previously occupied by the gasket.



It is very important that the surfaces that will be sealed with silicone be clean and dry.

Also the crankshaft and seal must be absolutely free of oil.

I REPEAT NO OIL IS ALLOWED ON THE SEAL OR CRANKSHAFT DURING ASSEMBLY OR IT WILL LEAK.

The seal is made of Teflon and must be dry to seat to the crankshaft.

 

[SRadke]

Your seal wasn't aligned with the crankshaft? The install tool does that for you. You tap it in until it bottoms the tool on the crank and it will be square. I've done dozens of them, never had a leaker.

 

[TBartlett1]

That's correct; it was not properly aligned with the crankshaft.



It has nothing to do with the seal not being square, too deep or shallow.

The installation tool aids installing the seal over the crankshaft and into the retainer and sets the depth.

The issue was the seal retainer was not properly installed or moved during engine assembly. How it happened I do not know but it did.

I purchased this truck new in 1990 and currently the 3rd seal is still leak free after 100K.



I'm a mechanic myself and I installed the first 2 seals as you mentioned but after 2 failures I knew something was not right. What I noticed after the 2nd seal failed was heavy wear on 1 side and light wear on the other.

During installation of the 3rd seal I noticed the seal was being crowded on 1 side as I attempted to install it so I removed the retainer.



Removing the seal retainer and installing the seal in 2 steps makes it a bit more manageable and adds less than 1 hour to the job.



Edgerman may have better luck (results) if he does as I mentioned and will require only 1 additional gasket and a bit of silicone.



Tim

 

[edgeman]

Thanks, sounds like I should be able to change it. Is the $50 kit available at the local NAPA store or from Cummins, I think its best for me to use the tool.

 

[SRadke]

So it was an off center issue, not an out of square issue. Makes sense. Hard to believe the original one lasted as long as it did.

I buy them from Cummins or a Cummins dealer. The part number is easy to find here with a search but they can look it up with your engine number.

 

[RyanStewart]

I'm interested in this too as I plan on doing mine pretty soon. TBartlett1, it sounds like you had to remove the adapter plate on the back of the engine in order to do the job properly but SRadke didn't have to, correct? Could this be because the adapter on TBartlett1's engine wasn't lined up 100% correct so the seal would go in properly with it in place? Just a theory, but in any case is its true would there be any way to tell if the seal was going to go in properly before removing the adapter?

 

[Ol'TrailDog]

Just to pass along one of my "learning experiences"



I replaced the rear seal on my 97. Did the clutch and replaced the pilot bearing with one of the fancy pilot bearings that required the hole being machined a bit. I also now remember getting the flywheel off was one incredible challenge involving a come along and slide hammer... . amazing.



Anyway, when I got it all back together the rear main still leaked just like before. That is when I came across the bit o' TDR advice to check your last two rocker cover gaskets because they can make it look like you have a leaking rear main... ... ... ... DOOAH!!! Another lesson from the school of hard knocks for OTD. Thanks TDR.



Perhaps relating this can help someone else in the future. By the way, I'm now trying to figure out the miss on the Subaru's #4 cylinder under load (code P0304). Changed the plugs, wires,... coil... will be looking at the injector connections tomorrow and then pulling the injector??? Don't think its the fuel filter or it wouldn't be consistently #4. Any advice would be appreciated before I get around to eventually replacing the entire engine piece by piece.

 

[Extreme1]

I'm now trying to figure out the miss on the Subaru's #4 cylinder under load (code P0304). Changed the plugs, wires,... coil... will be looking at the injector connections tomorrow and then pulling the injector??? Don't think its the fuel filter or it wouldn't be consistently #4. Any advice would be appreciated before I get around to eventually replacing the entire engine piece by piece.

Pull the injector and have it tested at an injection shop. It's only a few dollars and they will be able to tell you quick if it's the problem.

 

[TBartlett1]

Ryan Stewart

Yes I needed to remove the seal retainer to do the job properly.

Doing so allowed me to use a press to install the seal into the retainer.

I didn't remove the retainer because the seal was difficult to install, I removed it because something did not look right.



If I ever do another seal on any Cummins I will do the same and remove the retainer again because then I will know he seal is aligned perfectly with the crankshaft.

I prefer to assume nothing is perfect and take a few extra steps to satisfy myself that no details are missed especially with something as labor intensive as a Cummins crank seal.

Tim

 

[edgeman]

Thanks again! I ordered the clutch today, and will be getting the seal with the tool to install it with on Monday. I will be looking at the valve covers real close tomorrow also. I think that the oil leak has let oil get on the clutch, and that is what has caused the clutch to start shuddering at take off. Thanks for the tips.