After getting the D4-6U # 2831 unstuck recently, I replaced (for the first time) all the oil in the engine, hydraulic system, transmission and final drives.

The engine (bypass system) filter cannister had no inner element, just the metallic strainer element , probably because it was such a pain to get the filter cover thread to start.

After working the CAT for about a half hour, the left rear sprocket was covered with oil that leaked out of somewhere. Why would oil leak that much after a change? It leaked before but not all over the sprocket. What kind of a repair job am I looking to?

I have another question - After starting the pony engine and disengaging the starter clutch, the pinion engages the flywheel ring gear in only about one out of a half dozen attempts. The gears do not clash - they just will not mesh. Once the gears finally do line up the meshing is smooth. What causes the apparent misalignment of the gears? Is there an easy fix for this? Would running the pony too fast cause the refusal to engage?

I'm having a lot of fun with the perpetual challenges of this CAT. Thanks to all you experienced guys on this forum the various hurdles are gradually fading away.

Fred (tinytec)

Most of these old Cats got converted to full flow oil filters many years ago. The conversion used to come in a kit but I don't think it is available anymore. Takes these parts to convert. Any D2/D4/D6 with the can type filter housing would be a candidate for salvage parts. The conversion will have a new stem and screw so your thread problem should get resolved.

You might try tightening the final drive outer bearings but there is a good chance the final seals are shot. Fairly big job....split track, detach track truck...pull sprocket to get at seals. I suspect the oil level was not high enough to leak out much until you refilled it.

Yes, turn down the revs to engage pony pinion.

OM maybe he,s not applying the clutch brake on for the pinion shaft to stop rotating. Fred, as OM said idle the starting engine down and the brake is applied by pulling the clutch lever back hard & hold it there then snap the pinion engaging lever up to engage it and see if it goes in better now & then you can push the clutch lever ahead to turn the diesel over.

OM and SJ Thanks again for the new info. I'll try slowing the pony down in the future. I operate the clutch and pinion levers as you instructed.

The final seal sounds like more than I want to get into at this time.

Fred (tinytec)

Can you tolerate a couple more questions about the D-4 final drive anatomy?

1. Is the oil circulated only by splashing of the gears or is a pump involved?

2. When the oil leaks through the seal, and the level is down to its lowest point, about how much oil is left?

3. When it has leaked down to the lowest point, are the gears still lubricated enough for safe light and operation on level ground?

Thanks again!

Fred

Sure can:D
There is no pump involved. Just the bull gear dipping into the oil and carrying it up to the drive pinion and bearings for lubrication.
The oil level is fairly low (well below the dead axle level).
The oil just keeps being circulated by the bull gear and drains to the bottom to go around again. A certain amount would leak by the seal. So long as there is enough for the bull gear to pick up you are probably ok. Just keep adding some until you get around to repairs. There is no minimum or reserve level. The bull gear runs pretty close to the bottom of the housing and is capable of pretty much draining it.

I only just mentioned it before but it would be worthwhile to check for outer bearing adjustment. Jack up the rear of the tractor to take the weight off the sprocket and use a five foot crowbar between sprocket and track frame to see if you get any lateral movement. Loose bearing adjustment can effect the final seal operation causing leakage. Post your findings if you need instructions on tightening.

Thanks OM. I'll probably check the bearing adjustment some time this week and post the results. It would sure be nice if an adjustment took care of the leakage - certainly better than a major repair job.

Any work I do on the machine is very awkward because my tools are seven miles from where the CAT lives - that's where I still own about 20 acres of farmland where I gew up as a kid 76 years ago.

Fred

OM, today I checked the end play on the leaking final drive sprocket. It moves back & forth about 3/16 inches I also checked the other side which does not leak oil - it has no end play

That sheds some hope on a solution to the problem. I don't have a spanner wrench so will have to come up with some alternate way to tighten the bearing adjustment.

Why would one side wear so much as compared to the other side - any ideas?

Fred

Hi Fred,
That sure would qualify for a leaker......also can result in bull gear and pinion damage if left unattended. Can't remember if you said you had a manual or not so instructions are attached. That spanner doesn't work so hot with the track on anyway. Try using a combination pry bar and intermediate lever engaged in the nut.
Wear/looseness tends to be aggravated by the direction most frequently used in turning. More common on discing tractors but applies to dozers as well.