Hydraulic Pump Seals - My turn to cry

[thclimer]

Hi Jim,

Sorry to learn about your leak. Good catch on your part.

What would be your guess if it continued to leak and you didn't see a puddle on the ground?

How difficult is it to access and remove the pump?

Looking forward to the pictures as well.

Tim

 

[wdchyd]

Jinman,

Is that a KAYABA Hyd gear pump..??

 

[jinman]

Jinman,

Is that a KAYABA Hyd gear pump..??

I know it's a gear pump, but I haven't pulled it yet and don't know for sure if it is a KAYABA. That does sound familiar, but I'm just not sure. I've had a contractor at my house doing siding most of the week and we've been finishing up our garden. Since all the tilling/bedding is done, I don't have a lot of need for the TC45D right now, so I've put off pulling the pump. I'll check the brand after I get it off. It's a 9.8 gpm pump at 2500 rpm. I know the spec, but just don't know the manufacturer.

EDIT: Oh yes. . .almost forgot. I pulled the engine dipstick and looked at the oil level yesterday. You really can't see the dipstick that well in this photo, so I pointed at the spot where the engine oil level is. It is WAY above that full mark where my finger is pointing. I'm guessing at least 3 quarts overfilled. It wasn't running out of the dipstick hole yet, but the crankcase vent was running a solid tiny stream and making puddles on the ground.

 

[Jerry/MT]

I know it's a gear pump, but I haven't pulled it yet and don't know for sure if it is a KAYABA. That does sound familiar, but I'm just not sure. I've had a contractor at my house doing siding most of the week and we've been finishing up our garden. Since all the tilling/bedding is done, I don't have a lot of need for the TC45D right now, so I've put off pulling the pump. I'll check the brand after I get it off. It's a 9.8 gpm pump at 2500 rpm. I know the spec, but just don't know the manufacturer.

EDIT: Oh yes. . .almost forgot. I pulled the engine dipstick and looked at the oil level yesterday. You really can't see the dipstick that well in this photo, so I pointed at the spot where the engine oil level is. It is WAY above that full mark where my finger is pointing. I'm guessing at least 3 quarts overfilled. It wasn't running out of the dipstick hole yet, but the crankcase vent was running a solid tiny stream and making puddles on the ground.

Jim,

Sorry to hear you are having problems. But machines always fail, eventually. You apparently have violated Murphy's law because you say you didn't really need the tractor right now. (Can you share the secret on how you managed that? (Grin)).

Since I'm not familiar with your tractor, can you explain how the oil from the HST pump ends up in your crancase. The engineer in me wants to know.

 

[jinman]

Since I'm not familiar with your tractor, can you explain how the oil from the HST pump ends up in your crancase. The engineer in me wants to know.

Jerry, it was the main hydraulic pump for the 3PH and loader, not the HST pump. Since the main pump is gear driven off the engine, if its input shaft seal fails (actually two seals: inner/outer) all the fluid goes directly into the engine. The first clue you have is the engine oil pan or crankcase breather overflows. Now, my tractor has a separate power steering pump and that one could be the problem, but it would only have about 1 liter of fluid before draining the reservoir. Since my oil pan is 3 quarts over, there can only be one source, the main hydraulic pump.

The reason I don't need my TC45D at the moment is I am doing most work with my New Holland LB75B TLB. It's not as nimble as the TC, but it gets the job done in a pinch.

 

[Jerry/MT]

Jerry, it was the main hydraulic pump for the 3PH and loader, not the HST pump. Since the main pump is gear driven off the engine, if its input shaft seal fails (actually two seals: inner/outer) all the fluid goes directly into the engine. The first clue you have is the engine oil pan or crankcase breather overflows. Now, my tractor has a separate power steering pump and that one could be the problem, but it would only have about 1 liter of fluid before draining the reservoir. Since my oil pan is 3 quarts over, there can only be one source, the main hydraulic pump.

The reason I don't need my TC45D at the moment is I am doing most work with my New Holland LB75B TLB. It's not as nimble as the TC, but it gets the job done in a pinch.

Let me make sure I understand this. Your main hydraulic system pump is directly engine driven and is located in the engine crankcase or in a location where shaft leakge can get to the engine crankcase? So if a hyrdraulic pump seal leaks you contaminate the engine oil. Have I got that right?

 

[Jbrink64]

Jinman, I've been looking at this thread with interest.

The pump shaft seals are on the suction side of the pump. When those seals fail, and the engine is running, the pump will draw engine oil and air into the hyd system. With the engine off, hyd oil can pass into the engine, but the pump is very close to the hyd oil level.

I guess the hyd oil level has dropped the 3 quarts that went into the engine? If not, could the engine be filling with fuel?

I just hate to see you spend the time/money fixing a pump that wasn't the problem.

 

[jinman]

Let me make sure I understand this. Your main hydraulic system pump is directly engine driven and is located in the engine crankcase or in a location where shaft leakge can get to the engine crankcase? So if a hyrdraulic pump seal leaks you contaminate the engine oil. Have I got that right?

Jerry, you have it exactly right. Below is a photo of the main hydraulic pump (on the left) and the power steering pump mounted on the engine boss so they can be driven by the engine oil pump gear located inside the engine.

 

[Jerry/MT]

Jerry, you have it exactly right. Below is a photo of the main hydraulic pump (on the left) and the power steering pump mounted on the engine boss so they can be driven by the engine oil pump gear located inside the engine.

Thanks Jim. After I posted, I went to the NH parts sites and found a dwg of how the pump system is set up. Sure looks easy to get at.

 

[jinman]

Jinman, I've been looking at this thread with interest.

The pump shaft seals are on the suction side of the pump. When those seals fail, and the engine is running, the pump will draw engine oil and air into the hyd system. With the engine off, hyd oil can pass into the engine, but the pump is very close to the hyd oil level.

I guess the hyd oil level has dropped the 3 quarts that went into the engine? If not, could the engine be filling with fuel?

I just hate to see you spend the time/money fixing a pump that wasn't the problem.

Well, I can assure you it is hydraulic fluid from the main pump. Not only is the oil not thinned at all, but it smells just like hydraulic fluid instead of engine oil. The dipstick for the hydraulic reservoir shows no fluid. It really only measures the last gallon of fluid in the reservoir. When you lose a gallon, there will be nothing on the stick.

Jbrink64, thanks for your concern and respoinse. I'm a bit fascinated and confused that you would say the gear pump shaft is only on the suction side of the pump. If you look at a cross-section of the gears in a gear pump, the bottom half is low pressure suction and the top half is high pressure outlet flow. Neither is isolated from the shaft seal. The gear pump works because more fluid is forced around the outsides of the gear than can flow back (leak) to the low pressure side from the high pressure side. Below is a flow diagram of my hydraulic system showing the pump and fluid flowing top to bottom through the pump. Also here is a link to a website discussing gear pump operation. I don't see anything that would isolate the high pressure fluid or low pressure suction from being felt by the shaft and seal. The pump is a bit of a "magic box," but gear pumps have been pumping fluids for longer than I've been around, so they must work.:thumbsup:

BTW: The reason I said, "My turn to cry," in my title is that at least three other TBNers have reported the same problem with the same symptoms during the last year to year and a half. In each case, new pump seals solved the problem. One member had to have his pump rebuilt twice when the dealer failed to replace all the seals the first time around. Once all the seals were replaced with new ones, his pump worked normally.

The fact that so many of these pumps fail this way is exactly why I caution people against shimming their relief valves for additional pressure. My pressure is exactly 2500 psi. If my pump fails with that pressure, shimming to 2700 psi is really playing Russian Roulette.