I have a D2 5u.
Do all the cat 44 pumps use 10w or 30w motor oil in the pumps???? If they do I made a big mistake.

Thanks

"tinytec" wrote:

The hydraulic fluid was low so I added regular hydraulic fluid. Apparently it's not compatible with whatever is in the reservoir as a grey-colored fluid oozes out from around the control shaft on the pump reservoir. Does this sound like water in the hydraulic system?

Thanks again for any help.
tinytec aka Fred in upstate NY

More than likely you will need to replace the seal around the control shaft. My D4 had the same problem. Years of sitting with rainwater landing around the top of the resevoir leads to pitting of the shaft and will allow water to enter the resevoir. To replace the seal, you will need to remove the front cover of the pump (after draining the fluid), then you will need to dis-assemble the shaft from the bell crank and internal control rods. There are a couple of woodruf keys, so be careful when you remove them, or keep a strong magnet handy to search the ground once you drop them. The seal part number is 11223 (Chicago Rawhide) and can be bought from Motion Industries for about 4 bucks a piece. Or you can go to your Cat dealer and buy the same part for about 40 bucks. There is enough room to install 2 seals, which I did just to allow sealing around a non-pitted area of the control shaft. Good luck.

Hi timb,
The Operators Manual clearly states that you should be using crankcase oil (detergent) in all the #44 units. It depends on what hydraulic oil you have in there now as to how concerned you should be. Hydraulic oil is non-detergent but if you are using a correct viscosity oil it's not that big a deal. The best choice of oil should be based on the following info:

ISO grade SAE grade Viscosity SUS@100 deg F.
32 10W 155
46 10 215
68 20 325
100 30 525

The original weight recommended by Cat is on the light side (10 or 10W)
For general use hydraulic systems I run the ISO 68 (in Calif. climate)
For a tired pump and system (again in Calif) I run the same 30wt as the engine.
To me it is a case of judgment with choices available that didn't exist back then.
I believe the thinking back then was to use a detergent oil to keep crap in suspension so that it is removed by the filter but this by-pass filter is restricted to a very low flow. In my opinion there is nothing wrong with considering this system to be like a modern hydraulic system which will operate fine, maybe even better on current hydraulic fluids.

Well I see the format does not allow columns. The first number is ISOgrade, second number SAEgrade and then viscosity

ccjersey, Old Magnet, SJ, B4D2 . . .,

Thanks again for all the information! I removed the carb. top end again today and found a totally-plugged little jet that's in the middle bottom of the bowl. Cleaned it then set the float to where it was about level with the top plate and whoopee! the pony started right up and runs superb. I never saw that little jet until you mentioned it.

Topped off all the oil levels and bulldozed a creek bed that I started on a while ago. It is so mucky the cat almost got buried.

Bought 8 gallons of 10W for the hydraulics but was too pooped after working all day to do the oil change. Have to do that next time.

Love the story about the guy's nuisance "ex-car". Looking forward to 20-20 vision in a few days too.

Thanks again guys. As always you're the greatest bunch!

Fred in upstate NY (tinytec)