Mnie is powershift, yes...

I'll look for serial numbers today...

Here's the numbers I got:

HYD Control 163
39G4409

Pump has a label with hand engraved numbers: (I had trouble reading them)
79079681
6J 7400
8-03

I'm assuming it was rebuilt in August 2003?

The sight glass for the HYD was full this morning, as I ran the machine, the sight glass was empty. When I shut the machine off, the sight glass filled up with oil again.

When I started it this morning, the trans oil was halfway between the two marks designating full.

After I ran it today, I checked the trans oil again, when the machine was hot, it was at the lower of the two lines... Shouldn't it read higher when the machine is hotter?

Here are some pic's... The leak is most definitely coming from the adapter plate where it bolts to the bell housing, it runs right out. The bolts were not loose. Problem is it looks like it's leaking from both front and back of the bell housing...








I sure as hell hope I don't have to take the pump off that is behind the bell housing, looks like the entire ROPS and maybe dash would have to come off to get that out...

OK,
39G4409 is the serial number. There also should be an arrangement number on there somewhere. The 6J7400 is the pump number that probably was replaced or rebuilt 8-03. The tank & valve group is a #3J3898, and uses a #5J9869 valve group (two valve). My books do not show the later #6J7400 pump but I am including a (best guess) parts breakdown of a typical pump.

You need to get a good power wash of the leaking area and see if you can pinpoint where all the oil is coming from. It's hard to tell where all the oil travels too but origin seems pretty high up.

Hate to say it but cracked bell housings have come up as a topic a time or two.......

Thanks for all the help OM.

Yes I need to clean the area, but in this next picture, the red circle represents where the majority of the oil is coming from (the clean band running down). Abaout a 3/4" wide stream of oil running down, pretty much right in-line with the shaft of the HYD pump...

The red line shows where it seeps out a little bit...



I certainly hope it's not a cracked bell housing, can't imagine how I could have done that...

I'm still confused as to where this oil is coming from... I guess I have to let it leak more, and see where I lose it, HYD tank or transmission?

Draw down on the operating hydraulic tanks is pretty normal. Does seem like your losing ground on transmission level.

When did all this start??? recent or all along??
Could be anything from a sloppy pump installation...no "O" ring....to something more serious.

Is there some type of real bright DYE I can put in the HYD tank?

Might help me determine which one is leaking...

So if I'm losing transmission oil, it's either this pump is leaking:


Or I'm losing it via a cracked bell housing, or a leaky bell housing o-ring...

I think for the volume of oil I see, and considering it's getting worse day by day, it would seem like a pump seal going?

I mean, if it was a cracked bell housing, why did it take months to leak more and more, would it not have leaked the instant I cracked it the same it does now?

From memory OM, this started to leak maybe 4-5 months ago, in the middle of winter. If I left the blade up while idling and moved, I'd see a silver dollar sized oil spot. If I put the blade down, no leak...

Now, you can see the oil spots in the picture, are from about 2-3 minutes of idling in one spot with the blade down...

This did not leak last summer when I put a good 200 hours on the machine digging a pond...

Don't know about dye but using automatic transmission fluid (the red stuff) in the hydraulic system has been done for just that purpose. The only reason I would think cracked housing is if both pumps were leaking in the flange area. Ya need to do some more sleuth work before jumping to conclusion.

I have a vision of a hydraulic pump installation goobered up with silicone and used or no "O" ring. Always check the last work done first.

Yeah, I was going to try the ATF, but figured 1 or 2 gallons would just get diluted into the rest of the oil and not show up as red...

I figured a more concentrated DYE would be better, all I found on the net was UV dye, in which you need a UV light to see it...

Hi ETD66SS,
Cat uses a black "O" ring in that application so it is most likely that the seal is cooked hard. It is subject to T/Conv., engine, and hyd. heat in the adaptor's location. Your red line clearly shows the leak to be at the pump drive adaptor/flywheel housing face joint. The Hyd. pump needs to come off to get the adaptor out, then you can inspect the flywheel housing opening and engine mount areas.
Other possibility is that the T/Conv. scavange pump is worn and not emptying the flywheel housing properly or the T/Conv. is leaking excessively and the scav. pump can't keep up or both. This in turn puts extra sealing load on the "O" ring.
There was discussion on this subject recently for a 977 I think. The flywheel housing and the pump acessory drive gears within are lubed by trans. oil. I am sure at the dealer we had to remove the intermediate pump drive gear to Dyno these engines as the gear bearings are lubed from the trans. and would run dry and seize up.
As for the red dye we used it at the dealer for such oil transfer tests and we used the dye used to colour the roller/idler/Salt track pin and bush oils. I think it is available in the Cat system, P/No maybe in a One Safe Source.
Cheers,
Eddie B.

Ed, that engine doesn't look like it has the adapter and gear between the flywheel and crank so the pump drive must be lubed by trans oil not engine oil like a 966 pump drive.
Later Bob