oil in the bellhousing d47u

Sum Tin Wong here!!

I wound up taking off my plate that I made to cover the area where the pony motor sat, and I see that it's leaking antifreeze under the block off plate, Im now starting to wonder if water was leaking between the bellhousing somehow? I had just filled it up yesterday and when I checked the water level it was a little lower than yesterday, and when I cleaned the starter I seen a bit of antifreeze as well,
So could my thinking be correct that its just a matter of needing a better blanking plate for the pony motor cover?

be aware that there is a serious design flaw with the rear crank sealing on D47U in that there was no effective seal to prevent oil leaking back into the flywheel housing from where it is almost impossible for it to flow back to the sump. Cat recognised that when working on steep slopes the sump will eventually empty into the flywheel and bellhousing and the engine will sieze. So they brought out a field mod that consisted of a large oil seal that runs on the flange at the back of the flywheeel. But you must split the tractor to fit the seal. The seal is still available but in Aus it costs around 200 dollars!!

If you are finding this trouble when working on steep slopes, that could be your problem. Another solution my neighbour used back in the day was to fill the flwheel and bellhousing with @4 gallons of oil. That way it does not matter if the oil flows back and forth to the engine and ironically it made the clutch plate last a lot longer - something Cat did later on.

PS I learnt the hard way and it cost me Au4k to rebuild a siezed engine😞

Hi Inter,
I have a later model D25U13753 (just after the change to the two-piece clutch shaft) - would I be able to fit an oil seal to my engine? I'm about to pull the engine out to look at the crank so now would be the right time to fit the seal if it's possible. Also, would putting oil in the clutch housing apply to this tractor as well?
Would the seal and clutch oil also work in my older 3J?

Neil, when you get the crank out, bringing the rear main bearing clearance back to spec is going to stop most of the leakage. There were a lot of CAT tractors built with dry clutches and that screw thread-rear main bearing oil retention system and if it was a big problem for most of them, it "never made the news". Of course oil clutches came out in the latter part of the life of that design, so that eliminated the problem quite neatly where they were used.

I can certainly see a tractor working up and down a slope getting into trouble with the oil migrating. I recall discussion on her about similar work situations causing problems even in later tractors when the powershift transmission pump sucked air and the transmission went into neutral. CAT put out bulletin recommending overfilling those transmissions when working on slopes to avoid a dangerous quick ride to the bottom.

Thanks cc - even so, I'll take a look when I have it apart to see if there's even the possibility of fitting a seal in there somewhere - figure if I have it apart, it won't hurt to investigate.

I dont think it is such a problem with the D2 engines due to their design being different. I have a D2 and was panicking that the same issue might arise as happened with the D4 30A (7U). So we closely examined the D2 and noted the design is different to the D4 and in addition the flywheel is much smaller in diameter than the D4 meaning the problem casting pathways are located higher above the sump oil level than in the D4.

On the D4 from memory it is possible for the oil to spill out of the sump into the flywheel housing via casting arrangements essentially by-passing the crank seal on steep slopes such as a dam face. The D2 does not appear to have this problem as the relationship between the flywheel housing and the sump and the shorter track base is such that the tractor would need to be on a very precarious angle for it to happen to any degree.

I have not heard of this being a problem for D2s but everyone who has owned a D4 7U in my area has and it was something they needed to be aware of when operating and or to fit the seal which essentially allows sump oil into the flywheel housing on steep slopes but prevents it from entering the clutch housing. A new hole is also drilled into the back of the sump allowing the oil entering the flywheel housing to flow back to the sump and the existing relief hole which is located much higher is blocked.

Good info guys - only reason I was concerned is because a fellow here in NY was pushing uphill with his 5U and ran a bearing. It's possible he was low on oil in the first place so that might have exacerbated it but still....