D6H trans oil level

[tracksfan]

my D6H ser#4RC1088 trans oil level is doing something odd. after it sits unused for a couple days the oil level on the dipstick, cold oil and engine off, is way low, about 4 gallons or so. When I start it up and get it to operating temp its within the high and low marks for engine at low idle and warm oil. When I shut it down and come back the next day it reads between the marks for cold oil and engine off, let it sit for a few days and it reads low again. so where is the oil going?

Can it be drawn slowly into the torque somehow when the engine is off?

Can it leak from the trans case into the sump? (where the trans clutches are) not sure if I'm calling these compartments the correct name. When I open the back cover on the trans the clutches are submerged about halfway under oil. Does anyone know if this too much oil around the clutches? Is the scavenge pump suposed to keep the oil level drawn down to the bottom of the clutches?

This is got me scratching my head in puzzlement

 

[Jimbo]

I am going to bump this back to the top, in hopes of Nige, Lee, Gavinh, or one of the other very knowlegeable Cat tech's on here can help, as occasionally my D6HII does the same thing.
Thanks guys, Jimbo

 

[Multiracer]

I can not help with your situation,
But, I can offer that my D-6H series II never really gains or looses oil after extended periods of running or non use.
Ron

 

[tracksfan]

Thanks for the replies.

Some additional info.

It runs fine except after an hour or two the powertrain oil temp starts to climb towards 250-260 degrees. The temp returns to around 200 real quick in neutral. The temp jumps right back up in first gear when I run it back and forth with the blade off the ground or no load. oddly enough I can operate it in second gear under a moderate load and it runs around 220. This is on days of mild weather of 50-60 degrees.

I've fixed numerous trans problems on this machine over the years:

- routine oil samples indicated problems which led to

- leaking inner final drive seals, replaced the seals and changed the oil.

- oil samples still indicating problems which led to

- replaced worn friction disks and plates and seals in the trans and steering clutches and brakes.

- trans oil filter bypass indicator was coming on at startup due to bad temp sensor, replaced the sensor.

- I thought the trans oil cooler might be restricted with debris, looked ok except the rubber on the ends was deteriorating so I replaced it.

-I've put 2500 hours on the machine since I got it used 15 years ago. The total hours and prior history are unknown to me.

- no issues with the engine temp

- I realize now I should have gone through the torque and pumps at the time of the trans repair but did not.

- pressure tests were within spec although I'm not sure if I did it right. torque inlet pressure was 90 psi, book spec is 100 psi plus or minus 10.

I'm thinking maybe the pumps are worn and lose performance and the torque seals are leaking as the oil heats up? And or the first gear clutch is slipping? I don't see how that applies to the oil fluctuation problem though. If the torque is filling up with oil when I'm running it and the trans sump is overfull because the scavenge pump is not keeping up, then the oil level in the case should go down not up, right? Then maybe the oil works it way back into he case after it sits for a couple days. This would be the opposite of the problem I am having.

 

[tracksfan]

thought of some more stuff

- installed temp guages recently, so I don't know if it was running hot before that.

- Cut open and inspected the trans filter this week, found a few dark specs so small i could barely see them and some small yellow flakes, paint maybe? looked clean other than that.

- suction screens were clean last time I checked approx. 75 hours ago? only a few small particles which I would guess is not unusual after the trans repair.

- I have pulled the suction line off the torque and drained it a couple of times and get about a gallon out of it. Not since the oil cooler repair approx. 75 hours ago.


How much oil typically comes out of the trans sump when you pull the suction screen at the bottom of the trans housing on the rear of the machine? does 20-25 gallons sound wrong? I still had the drain plug in the trans.

 

[jake980]

hey tracksfan... transmission oil levels can be a very tricky thing... and can be very tricky to get just perfect. I typically get the machine to operating temperature and adjust the level if its a bit high or low, while i leave the machine running. Draining it can be done by hooking an open ended pressure test line to the torque outlet and draining into a pale. As for what you said with the torque overfilling and the scavenge pump not keeping up... this is highly unlikey but i guess possible. If your torque overfills that much, you will notice a significant lose in power. This would also likley lead to a failed engine rear main seal, and trans oil entering the engine. If you pull the suction screen at the bottom of the trans.. you will vertually drain all your transmission oil. If you are worried about oil bypassing your clutch seals, try hooking up gauges to each clutch and running the machine. You will see the pressure drop when that clutch is selected. To me your machine sounds like it is in good working order? did you notice while operating it, that it feels like clutchs are slipping or its very low on power? good luck!

 

[tracksfan]

Jake980, Thanks for the helpful info. I don't notice any problems like loss of power or the trans slipping, it runs good. It is noisy like a howling sound though. I would think everything was ok if it wasn't for the oil level issue and high temp reading on the gauge. Maybe I should follow one wiseacre's advice and quit looking at the gauge....

 

[tracksfan]

I removed the trans pump so I could take it apart and see what shape its in.

There is some scuffs on the flat plates of the scavenge section that I can see but feel smooth when I drag my fingernail across it. I slipped a .010 feeler gauge between the gears teeth where they mesh together. That seems like too much but I don't have a spec to go by.

The lube section looks ok.


The charge section has some pits on the flat part of the housing and a scratch that i can feel with my fingernail. There is also some wear visible on the round section of the housing. There are some parallel marks or lines spaced 1/4" apart, are these wear indicators? They are very hard to see where the round part of the housing is worn?

The shafts look ok, I can't feel any ridges. They are shiny where the bearings are. The bearings look a little worn, the color is sort of a mottled light grey. The gears fit snug in the housings according to my eyeball. I have specs for the bearing wear but no precise way of measuring it.

If I could get an idea of how much wear is too much that would be great. If the gears and shafts are ok then I could replace the bearings and the flat section of the charge pump, its the side shared with the lube section, and the housing section that the gears sit in and new seals? Or should I look into a reman pump?

pics next post

 

[tracksfan]

the pump ready to disassemble, the scavenge gears, scavenge plate, 2 pics of the charge pump plate/housing

 

[Gavin84w]

The pump looks fine, those gear style pumps have just about got to not have gears in em before they don,t work as they should.

If you are going to replace the bearings be careful when installing the new ones and take not on the old ones where the split in the bearing was, ensure the new ones are positioned in the same spot. It helps if you have an old shaft/gear to install them as it holds everything in shape while you knock em in. Iused to use a round axe stone to go over the ends of the pump housings to clean them up, usually while in the safety kleen wash.

Have you had a look at the breather as yet?

 

[oldirt]

I had a trans gear pump in my 6D that was worn enough it wouldn't cool anymore.. they do wear out and it doesn't take much case erosion to happen. I see plenty in the faceplate in this picture, probably worse in the scroll area.

 

[tracksfan]

thanks for the replies.

I checked the breather by the filter housing, looked good. nice and clean