My D7H pumps oil out the breather on the hydraulic tank, had Ziegler Cat mechanic check it out and said dont know why.. I said how about hydraulic pump... he says no pump pressure 4000 psi tranny pressure 400 psi so oil wont travel that way. Transmission oil goes down, hydraulic oil comes up. Seems to me shes getting into the hydraulic system somehow anybody got any ideas other than hydraulic pump?
grandpa, I don't know anything about a D7H, but I'm curious nevertheless. If, in fact, your tranny fluid is dropping in level and hyd reservoir fluid is rising, it seems there has to be a connection of the two. And I agree with you, the only place that hyd and tranny fluid is even near each other would be the hyd pump for work equipment. I assume the hyd pump is mounted to the convetor housing and is driven by the torque convertor. If so, is the convertor housing a wet sump housing? If it is, is the pump mounting within this oil sump level? I assume it's a wet housing because something has to lubricate the gear that drives the pump. Here's what I'm getting at, and this depends on if what I said above is correct. The Cat mech was correct that the pump develops XXXX psi pressure. But, he's overlooking that it develops this pressure "after" it has a vacuume to draw oil to develope this pressure. And this vacuume could draw oil from a wet sump convetor housing by the shaft seal of the pump, effectively draining you tranny fluid level. But it would be highly unusual for this vacuum to draw oil or fluid by the shaft seal, unless something was restricting the flow of oil through the oil supply line to the pump. It could be a kinked suction hose to the pump, could be a foreign object in the supply line. I worked on a Komatsu D41 once that kept trashing hyd pumps. I tried everything I could think of to resolve this problem until I finally told my helper to take every line off the hyd system looking for a problem. When he removed the hyd tank, we found a large stick lodged in the suction pipe that feeds oil to the hyd pump. In this case, the obstruction in the suction line caused an increase in vacuume by the pump. This vacuume caused the pump to suck air by the shaft seal of the pump and cavitated the pump with air, which destroyed numerous pumps. If your pump is within/below wet sump level, and you have a restriction in the pump suction line, you will draw oil by the shaft seal of the pump.
Over full hydraulic tank? Check for correct level. You need to be more specific. Are you assuming the oil coming from your hydraulic tank is diluted with transmission oil or do you know for a fact? And are you just assuming that there is oil being transferred into the hydraulic tank and overlooking the fact it's not over full? For example, say its overfull and the implements are on the ground. If you raise them, the oil level in the tank will increase due to the difference in volume from the piston to rod side of the cylinders.
Thanks Ateco for your input. The machine has about 2weeks work in the field yet before I can dig into it.(problem not detrimental to the machine, just makes a mess of the outside) I like your train of thought on the vacuum side of the pump.I am going to get to the bottom of this problem if I have to tear her clear to the frame to fix it. LOL. Needs to be done anyways just to get this sucker cleaned up again. When I figure it out I will let you know what it was! Again thanks for your help.....you got me on another train of thought!
Grandpa, The only place where the two systems meet is where the hydraulic pump is driven off the engine transfer gears which are lubricated by power train oil. Power train lube oil is very low pressure however and should not be able to get into the high pressure hydraulic system unless the torque were flooding but then you would have a whole new set of symptoms that you do not mention. Got a serial number? There are many D7H’s and I would like to make sure we are talking apples to apples.
Is this a diff steer tractor?Maybe oil from diff steer motor leaking into trans otherwise id say hyd pump shaft seals.
How's your hydraulic oil level there? :yup P.S. Love your name Grandpa!
yes it is a differenial steer machine. Ziegler Cat told me they had an episode where two hydraulic lines had rubbed together and the oil transfered from one hose to another without any external leakage...freaky. This cant be the case here because because transmission psi 400 and the hydraulics pressure is 4000. As atco stated gonna concentrate on the suction side of the hydraulic pump first. That the only place where pressures are low enough to allow for the transfer of fluids. Like I say it will be a bit before I can ger her in the shop to find out. Just trying to formulate some ideas into a plan of action Thanks for everybodys imput.... will save me time and money and ya gotta like that. Thanks chris the name grandpa just happens to fit. LOL
D7h Hydraulic problem Hi My guess is that the pumps for the transmission and implement hydraulics is mounted in serial. meaning that the transmission pump is bolted to the converter housing pto and the other pumps are bolted to the transmissionpump. If the transmission pumps starts leaking oil into the cavity between the pumps there is a real chance that oil may leak into the hyd.pump. The 40bar pressure from the transm.oilpump is enough to force oil trough the shaft seal of the hyd.pump. The pressure inside the housing of the hyd.pump should be around 1-2bars and is made only by the internal leakage in the pump. Hope you understand what i am writing here, my english is somewhat rusty at best
LoL, for someone from Norway, your English is quite well, even better than some in our "English speaking" country. :cool2