What is causing my crank seal to leak?

[basilry]

In the last 4 months I have replaced my front crank seal 3 times. The first time I put in a new seal and resealed everything up good. It didnt leak for about a day and then it started leaking again. I put it off for a couple of weeks and then tore everything apart again figuring maybe I didnt seal it right because it was the first one I ever did. The second time I had the same outcome. It wouldent leak for a day and then right back to leaking. So lask weekend I tore it all apart again and resleaved the crank and figured there would be no way that its going to leak. Three days later it started leaking again. What is causing this to happen? Is the crank building pressure and not able to release and blowing out the gasket? Is there some sort of vent that I dont know of that may be clogged? Any help would be appreciated, Im getting very frustrated!

 

[TBartlett1]

It's possible that the front cover has moved (creeped) slightly causing the seal to leak.

The rear seal on my 1990 leaked and I replaced it twice before I noticed that the closure plate that the seal was pressed into was not centered to the crank.

I removed the closure plate cleaned all parts then installed the plate with seal installed allowing the seal to properly align itself the crankshaft then I carefully tightened the screws and sealed the gap where the gasket use to be with silicone. .

This cured my leak.

It's possible that you may need to remove the front cover, install the new seal then reinstall it with the seal positioning the cover.

Also in the past seals that were made of Teflon usually stated that they needed to be installed dry so they can seat to shaft.



Hope this helps!!

 

[lmills]

And you are using the install tool to slip the seal over the nose of the crank?

 

[jakprince]

Im pretty sure it has to go in dry too. Get all the oil off the crank where the seal runs

 

[basilry]

Yeah each time I have used the tool to get the seal over the crank. And I made sure everything was very clean and all the old silicone was off of the cover before redoing it and putting it back together. The third time I even had a buddy help who has done them before on a 2nd gen and still the same results.

 

[jelag]

Have you checked your crankcase vent... crankcase pressure can easily force oil out a seal...

Also, a little lubrication on the seal is needed to prevent it from being damaged. .

 

[WM-300]

You mentioned removing all the old silicon but did you thoroughly clean all grease/oil off the seal surface on the crank shaft ?



Cummins Shop manual procedure 001-023 clearly instructs you to be sure the crank seal surface and seal is completely free of oil during installation. Failure to do so will damage the seal. These seals are installed DRY, No lubrication



Its also possible that the crankshaft seal surface is damaged ie, has a worn groove, pitting or other damage. If the seal surface is not perfect, Cummins makes a 'Service Wear Sleeve' this is similar to a speedi sleeve but has a much thicker wall.

A special tool is needed to install the wear sleeve, Cummins Part Number 3824500.

Believe me, without this tool, you will do damage to the Service Wear Sleeve, its that tight a fit. A damaged seal surface on the crank will take a new seal out quickly.



WM300

 

[WM-300]

You mentioned removing all the old silicon but did you thoroughly clean all grease/oil off the seal surface on the crank shaft ?



Cummins Shop manual procedure 001-023 clearly instructs you to be sure the crank seal surface and seal is completely free of oil during installation. Failure to do so will damage the seal. These seals are installed DRY, No lubrication



Its also possible that the crankshaft seal surface is damaged ie, has a worn groove, pitting or other damage. If the seal surface is not perfect, Cummins makes a 'Service Wear Sleeve' this is similar to a speedi sleeve but has a much thicker wall.

A special tool is needed to install the wear sleeve, Cummins Part Number 3824500.

Believe me, without this tool, you will do damage to the Service Wear Sleeve, its that tight a fit. A damaged seal surface on the crank will take a new seal out quickly.



WM300

Ooops, forgot to mention. If you use the Service Repair Sleeve, then a SPECIAL seal is required due to the larger diameter of the crank with the Service Repair Sleeve added.



WM300

 

[JamesStevens]

Are U sure it is leaking from the front seal? There is also a cam seal, and there is 1 more gasket behind the timing cover. I don't know what it seals or does, but the parts guy at Cummins gave it to us incase we needed it (we didn't) Check that timing cover for cracks to.

 

[InfernoB]

Also check end play.

 

[basilry]

I have not checked the vent yet, where is it located? I did make sure that all the old silicone was off of the cover and the front of the engine. The third time I changed the seal I put on the wear sleve and the gasket for the sleave. I have not had time to look at the truck but hopefully this week Ill have some free time again to tear it apart.

 

[basilry]

I finally got tired of all the oil that my truck was leaking everywhere and also getting tired of not having any time to tear it apart so I decided to drop my truck off at the Cummins dealer to have them deal with the oil leak. It turns out that the front cover itself had a very tiny hair line crack in it and that was causing all the oil leakage. They told me that they cleaned everything off and ran it for a while and could not find the leak until they put some die in the oil and then they found the crack. Im just glad its done with, one less thing for me to deal with. Just thought Id post what the result was. Thanks for all the help and suggestions.

 

[SShafranko]

TY for posting the result. Good info.

 

[JamesStevens]

Glad U got er, they can be hard to find. We still havent got my buddys