Has any one had problems with rear crank seals on a D339. I have a D7C 17A4242 that I rebuilt the engine, put in new piston liner mains and rods and both crank seals but I keep getting engine oil in my clutch housing. I but a jobber seal in first then I got a new seal and bearing from my cat dealer (new seal from finning was worse than jobber seal flush on one side of bearing and 1/4 " short on the other side and not nearly as high as it should have been. lip 1/16" lower than bearing) so I got another jobber seal a fraction of the price of cat and looked a lot better but that one also started leaking. any one have any suggestions. Thanks Jason

"Jason" wrote:

Has any one had problems with rear crank seals on a D339. I have a D7C 17A4242 that I rebuilt the engine, put in new piston liner mains and rods and both crank seals but I keep getting engine oil in my clutch housing. I but a jobber seal in first then I got a new seal and bearing from my cat dealer (new seal from finning was worse than jobber seal flush on one side of bearing and 1/4 " short on the other side and not nearly as high as it should have been. lip 1/16" lower than bearing) so I got another jobber seal a fraction of the price of cat and looked a lot better but that one also started leaking. any one have any suggestions. Thanks Jason

Here is a picture of the OEM seal and bearing. Hope the picture works

Hi Jason,
do not think this will help but here is the Service Bulletin:- Oct 02 1956, announcing the 2 piece seal.
Obviously some mismatch of parts or perhaps the seal steel case lip may distort further onto the bearing lip that it mounts to when the bearing cap is tightened or not.
Cheers,
Eddie B.

"edb" wrote:

Hi Jason,
do not think this will help but here is the Service Bulletin:- Oct 02 1956, announcing the 2 piece seal.
Obviously some mismatch of parts or perhaps the seal steel case lip may distort further onto the bearing lip that it mounts to when the bearing cap is tightened or not.
Cheers,
Eddie B.

Thanks Eddie for you reply. I sent the seal and bearing back to finning and got another seal, it fits a lot better so we are going to try it again and see what happens.

Hi Jason,
I had a silly thought over night that maybe the two piece seal could have one piece larger/longer than the other so that the main bearing cap to Cyl. block parting line and the seal sections parting lines do not coincide, to help prevent leaks--I am sure I have seen this in a Cat application at some time in my career--as ever I stand to be corrected.

I hope you have better success with the new seal pieces this time around.
Cheers,
Eddie B.

I rebuilt an old 65, 352 Ford eons ago. When I did the two piece rear main seal, the directions told me to off set the two half's of the seal so the seam would not line up with the seam between the main bearing and engine block. When you set the bearing the halves would draw up and seal together with an offset seam to the main bearing/block and when torqued they vulcanized to each other creating a single seal. Around the the outer edge between oilpan an bearing cap was a packed Oakum type seal.
That's what the offset seal reminded me of in the picture. Don't want to muddy the water here I just wanted to give a little deferent insight.

I got the new seals and they looked a lot better. both haves matched up with bearing haves or a little longer. I could not off set seals because of installation / bearing crush (seals fit pretty tight in cap and block and bearing has a grove for seal to sit in) going to try it out to day and see what happens with the new seal. Also seen after over haul that oil pressure was all the way on high side so I backed off oil pressure adjusting screw a bit. going to see what happens. We did a old D8 two piece seal about 4 or 5 years ago and had no problems, not sure why this one doesn't want to work for us.

Hi Jason,
thanks for the feed back and Dan for his addition too.
Good to hear the new set of seals seemed a better fit, but worrying none-the-less that there are faulty ones out there to catch someone out--good call to question the poor fitment.

We await your test results in due course.
Cheers,
Eddie B.

Put new seal in and it seemed to look real good. thought we had fixed the problem. Had a lot of dirt to push yesterday (perfect test) and we didn't make out to good. with cold oil i could go about two before I lost about 5 gallons of oil into the clutch as oil warmed up I was down to every hour stopping and draining oil from clutch and putting int back in the engine. starting to think I might have some thing else happening back there. once we have time I want to pull the bell housing off and see if maybe there is a missing or bad / popped out frost plug or some thing. Seems like a lot of oil getting pumped to clutch and it's getting hard to believe it's all coming from crank seal. Starting to think it has to be some thing else. Tore down engine a couple of years ago then the shop got extremely busy and the cat got put on the back burner. engine was apart for a couple of years so maybe we missed some thing back there.

The graders of that time shared to engine and clutch oil......successfully it seems. I wonder if you might be able to make an external connection to return the excess oil.

The first oil clutch graders (Late 8T series) used the flywheel to sling it up and back into the engine through a channel cast in the clutch housing and block. I’m guessing it still had the standard return thread on the crankshaft.

The 12E that came later just didn’t use a rear main seal as I remember but it doesn’t have the channel cast into the clutch housing

Seems unlikely you’re missing a plug back there since you’ve got normal oil pressure??