Hi SJ,
On the D7-17A a rear main seal was added at about sr. no. 5223. The crank stayed the same and the engine block did not change until 5065. My D339 Service Manual states the bearing bore stayed the same and a new bearing assembly accommodated the seal. My question is......do you recall if there was any problem converting prior engines to the rear main seal configuration?

OM I don,t have any parts books on the D7 or D8 But I know there was couple different types of sealing used in both these engines but I wasn,t aware there was a changeover you could put in the early one to the later style.If I recall early ones used the thrower & piston type ring & wear ring in the bell housing for it to ride against & later engines if I,m thinking right used the lip type seal. Cat was always up grading things so they may have brought out the kit to change things over but as I said I,m not aware if there was one.

In this case the early units just had the slinger and the oil return threads. The upgrade mounted a horizontal split seal to the new style bearing itself. I can't find anything that shows the upgrade to earlier units is ok. Not in field changeovers or attachments. Guess it would be best to leave it alone;) unless it shows up in a service bulletin. edb...got anything on this??? Thanks

Hi Team,
here you go, your lucky day, Service Bulletin (Engines)-- Oct. 02 1956--
should be what you require.
Cheers,
Eddie B.

Thanks edb,
WOW, that was way to easy:D . Sure glad you rat packed all that good info:)
Don't think I would of tried for conversion unless I had all the parts on hand to compare.

The question came about through a post for help in identifying why oil was flooding into the wet clutch housing on an early 17A. The rear main leakage and possible oil getting past the pony pinion shaft seal is all I could think of.

Hi OM & SJ,
is the oil leaking in, seeping in, or FLOODING in ?
Check engine and clutch housing breather (if oil clutch) for blockage, and engine blowby for starters.
The only parts book I have is for 3T, after a quick look through it, a 5 3/4" bore Serviceman's Ref. Book and a D7 Tractor SRB, all I can come up with is maybe the camshaft rear bore welch plug has dislodged, loose and/or fallen out flywheel housing studs, in back of block-- although I feel sure they are in blind holes, the rear of the sump gasket fretted out over the rear main cap or the rope packings between the block and rear main cap hard and shrunken, the seal you mention, or just plain worn out rear main bearing.
Loose/cracked flywheel housing.
These thoughts should give you a start.
Cheers,
Eddie B.

Hi edb,
The key word was "flooding" but I'm not sure if that is an exaggeration or not.
There is a welch plug at the back....at the bottom of a counter bore that would make it a candidate leaker......but it is covered by the bell housing. I'm inclined to think it is just plain wore out bearings on the early non-seal rear main.