Maroon belly 7000 oil leak from inspection plate

Hello all, my 1st post here. Many this question has been answered, but I can't seem to find it.
I have a AC 7000 maroon belly that works great. The issue I'm having is that once the pto is engaged, trans/hydraulic oil comes out of the front seal on transmission. The diff oil is lost and over fills the transmission compartment. I can use the tractor all day and not have any leak at all until I engage the pto and then ALOT of oil comes out and stops shortly after I disengage the pto. I'm not afraid of working on the tractor but have not had one split before. All help is appreciated, thank you.

When I engage the pto, oil goes from the differential compartment into the transmission which over fills and comes out the seal on the shaft that goes to the engine. I hope this makes sense.

The trans and diff are the same compartment use the same dip stick hyd uses the sight glass on the right front

Such a strange problem. On the model 7000 tractor, the 4-speed transmission is the rearmost part of the hydraulic sump, which is the torque housing. There is an oil seal on the main shaft/pinion shaft of the transmission, keeping the differential oil (and 540/1000 PTO gears) in their own little compartment. So, there is a large lip seal on the pinion shaft and double seals on the lower PTO shaft up in the front of the transmission housing. The differential/PTO gears oil level is checked and added at the dipstick behind the cab. You CANNOT check that oil level with the PTO running. Engine should be OFF and tractor sitting on the level.  There is a reverse idler shaft that could SEEP oil from diff to trans but it wouldn't be a fast transfer of oil I wouldn't think. An oil leak in the bellhousing when the PTO runs would require a split of rolling the engine away from the torque housing. I don't know why it only leaks when the PTO is engaged, but the PTO clutch is in that general area. I would be da&& sure to remove that belly cover and make it leak to see where the oil is coming from.

Edited by DrAllis - 27 Nov 2024 at 9:59am

That doesn't concern me as much as WHY the differential area is going down on fluid as you say.

I'm not doubting the oil leak inside the bell housing when the PTO is engaged. I am seriously questioning the complaint of the differential oil disappearing into the hydraulic sump. Never ever seen that and why are there two problems at the same time all of a sudden ???

Well, this is where I have a problem trying to diagnose this accurately. I am having a very hard time believing that oil is disappearing from the differential area to the hydraulic sump in a fast manner. I've also never had a leak in the bell housing area like that ONLY when the PTO was operating. Not saying it isn't leaking, just questioning why it's leaking. Are you SURE the hydraulic system is really OVERFULL?? Like  truly above the upper sight glass ??

The vent on the differential compartment is built in to the dipstick handle. If it was plugged it would take heat to push oil forward and that would take time to make the heat, so I don't think so, at this point. I asked and never got an answer: The differential oil level must be checked with the tractor sitting on the level and engine AND PTO OFF !!   That oil level cannot be checked with the engine running and PTO engaged as the 540/1000 RPM PTO gears are churning the oil inside the differential area. I see no way how checking the oil under that scenario would yield an accurate reading.

These are the 2 vents on the top plate of the rear diff. The rear dipstick does not have a vent on my tractor.

I see! Thanks for the clarification.
I've added about 2 liters in the back and that's about what came out of the front. I'll empty some as you say and see if it fills up.

Tractor has to be split, separating the engine from the bellhousing. Disassemble the PTO hollow shaft and see what's going on. It is related to the PTO clutch and it is in that area that you'll be working. I'm thinking the foot clutch may be oil soaked after all of this. New clutch and pressure plate and throwout brg and pilot bearing and rear crank seal/sleeve and both input shaft seals and gaskets. AND, try and figure out why the leak is coming from the area it's coming from. Might have to air check/test the PTO clutch while apart to see what's happening.

Thank you all for your patience with me and for your wisdom. One thing I noticed was that today I heard a rattle when the pto was engaged. Not sure that was because the hydraulic tank was lower on oil?
I will look into splitting the tractor. Not afraid of getting my hands dirty, but I am afraid of flipping the tractor as I've never split one before.

The "rattle" when the PTO is running is when the engine speed is under say 1200 RPM and is very NORMAL, so don't go thinking there's some else wrong.

Split the engine away from the bellhousing. Fix the massive leak that is going on the ground. If there is an "oil transferring" problem from the differential to the hydraulic system, fix that after the fact. Prove that you do have an oil transfer problem. 1/8" of an inch isn't a convincing problem. 2 inches would be.

My black belly seems to do the same thing when the PTO is on, and I have tried multiple front input shaft seals with no long term success.  I'm interested in what you find.  Granted they are quite a bit different design in regards to the input shaft, with the black belly having a solid shaft, but I do believe there may be something going on in the PTO clutch that is causing oil to be forced past the seal.