I've had a small leak in my HYD pump that is progressivly getting worse.

I lose probably 2 qts of oil in about 4 hours of use now...

What should I check first?

Return line is on top, where is the pressure line? I'm hoping it just needs an O-Ring...

My parts manual shows nothing on this pump...

My service manuals don't give any info on it either

Where exactly is it leaking? Pump is mounted on front left hand side of the bell housing. Pressure line is right next to suction line. The Hydraulic controls are covered in the #163 Hydraulic Controls Service Manual.

I just went to look at it again.

Neither line is leaking, the leak is farther back from the pump.

The leak is between the plate that the pump mounts to, and the bell housing...

I'm not losing any oil out of the tank, according to the sight level.

Is this transmission oil leaking?

Is there a gasket or o-ring behind that plate?

If you are losing 2-qts of oil every 4-hrs, where is it coming from?
I show an "O"ring seal #1H6227 at the face of the pump. What is the serial number of your hydraulic control unit?

OM, the 2 qt/4 hrs is a rough estimate from what I saw today...

During the winter I noticed it would leak a bit with the machine running and the blade in the air. It would stop leaking when I dropped the blade down.

Today is the first day since the leak started I really worked the machine hard, and got heated up. Now it leaks as soon as you start the machine. Not a drip, more like a very fine stream.

What exactly is the hydraulic control unit? The pump itself???

I'll have to get numbers off of it tomorrow. The return & pressure lines go into the top of the pump, it's not the type where they go into the front of the pump.

That intermediate plate that the pump bolts on to, the one that the stud for the blade tilt linkage is cast into, is that just an adapter plate? (or is it a bearing carrier with seals, etc?) If that goes to the bellhousing, how could it be leaking there? There's just a flywheel in there right? I have no section view of this in any of my books...

I'll take my camera tomorrow and get some pictures of exactly where the leak is...

Today is the first day I noticed I was leaving little puddles of oil...

Maybe the seal at the shaft of the pump is leaking and the oil is being thrown up by the flywheel to that joint and seeping out? Looking at that leak on top, that is not where all the oil is coming from, I have to take the covers off tomorrow, it must be leaking more underneath, , because it's a steady stream running to the ground, and not a steady stream coming out of that joint between that plate and bellhousing...

I have not had to add HYD oil in months... But honestly, I have probably only lost a gallon of oil in that time, so sight glass shows half...

Can I remove the pump without having to drain the entire HYD tank?

Check your engine parts book, the seal should be shown with the flywheel housing. The plate is the housing that holds the bushing for the drive gear and is pressure lubed from some place likely the engine oil galley. If it's engine oil lubed there will be an adapter on the crank infront of the flywheel with a drive gear in it. If it's engine oil the leaking oil should be black. If it looks clean not black it will be trans oil.
The Hyd control is the name given the Hyd tank inc valves inside, the pump and control levers.
Later Bob.

"bob" wrote:

Check your engine parts book, the seal should be shown with the flywheel housing. The plate is the housing that holds the bushing for the drive gear and is pressure lubed from some place likely the engine oil galley. If it's engine oil lubed there will be an adapter on the crank infront of the flywheel with a drive gear in it. If it's engine oil the leaking oil should be black. If it looks clean not black it will be trans oil.
The Hyd control is the name given the Hyd tank inc valves inside, the pump and control levers.
Later Bob.

It's definitely not diesel engine oil... It's clean oil...

The Hydraulic Controls consist of the tank with the control valves, pressure regulator and filter plus the pump and associated lines and linkage.
Serial number is on the upper front side of the tank (behind dash).
Along with the service information there is a separate O & M Instruction Manual and Parts Book covering the Serial Number for the unit.

I'm not sure I have the info for your serial number until you identify. The pumps use a variety of sealing, some with just shaft seals, some with "O" rings at the flange joints and some with gaskets.

Yes, could very well be oil coming from bell housing and not hydraulic fluid source.

System will have to be drained if/when it is pump removal time.

The Specifications Manual for the D6C shows the pump to be an 8J3635 which is beyond the serial number of the manuals I have. Going to need some help with later parts identification.

Ok, this is all I could find in my manuals...



The circled portion is where the plate mounts, which in turn the pump mounts to.

Here is a pic of it from my parts manual, but nowhere does it call out seals...



This is the pump unit that is mounted to the rear of the bell housing:



Is the cavity that these pumps are driven from, full of transmission oil? What oil level should I check? This oil is coming from somewhere, and it doesn't seem like it's coming from the HYD tank...

I checked the dipstick under the seat, it was full, that is the transmission oil correct?

Can't remember if your's is power shift or not....either way there is oil flying around in the bell housing....not full but used as sump for scavenge pump.
The seals you are asking about are shown in the #163 Parts Manual, just a matter of matching up the right parts for the serial number.
Transmission level is checked under the seat (engine running)

Here is the cross section of the pump drive and mounting showing a couple of seals and the blank cover where the pump would go. Additional sealing may come with pump. The drive is from a gear on the back side of the flywheel hub through an idler gear and to the pump drive gear.