D69U How to rebuild the hyd pump without removing from the machine?

Before you tear in to it do you have parts located? Recent similar project indicated the pump cartridge/parts were no longer available either new or used exchange.

What's the problem with the pump you have?
If it's low pressure, check the main relief valve in the tank first. They have been known to have broken springs which are still available.

Thanks OM... My next question was what is a lady to do, but but now I've seen your edited answer.

Hyd pump has no pressure at operating temp. Thanks for the heads up on the spring issue, this will be checked first.

We have bought another dozer for parts , it's a 1943 D69U. Don't know if its hyd pump is in any better shape due to the fact that it doesn't run. Either way one of them will have to be rebuilt eventually. Tank is in better shape on the 1957, the 1943 has been mashed in on the front.

Get serial numbers on the hydraulic units. Usually are hard to see on the rear surface of the tank, at top near the fill pipe. Look for the typical CAT small aluminum tag riveted on the tank.

The parts machine may be a 53, but cannot be older than a 48 and still be a U model. I suppose a #44 control could have been added to most any old tractor. I have a 46 model D2 that has one. Pretty sure it is at least a few years newer than the tractor.

You are going to have to drain the oil and take off the front cover of the unit to inspect the workings in there. I think you will have access to everything but the pump cartridge itself and the drive connecting it to the engine which comes in from the back.

This is a #46 Hydraulic Control. They date back to D6 4R/5R1 (1941) but there were many changes between then and the 1957 models. The serial numbers I'm after are found on top near the control lever. The older one s/n will start with a 1w____ the newer with a 25C____. I can tell you right now there is going to be limited interchangeability. Hopefully you may find out they are both of the 25C series.

Y'all are great and I'm an idiot for not proofing better and for doing replies with my little phone screen.

The parts dozer IS a 1953, not a 43. The only difference that we readily see is that the 53 is a dry clutch and the 57 is a wet clutch.

Hubby will be pulling numbers this afternoon while I do weekly shopping trip to town. I will post numbers this evening.

Does anyone have an expanded diagram of the innards to the hyd pump assembly and possibly a list of parts?

HAPPY MONDAY Y'ALL! and thanks again!

Obviously today is Monday and I have my head somewhere we won't mention... I just pulled my files and I HAVE diagram 4F9988 and 6F9393.

Just get the s/n's from both hydraulic units. I have all the diagram info needed.

Went to pull numbers on the hydraulic control unit and thisois the result :

1957 has plate that reads #1W2454 model #46
1953 has no plate
Stamped on the front cover of both units is 7F2704

OM..... I found my diagrams in my files..... Thank you!