Hydraulic Pump Seals - My turn to cry

[Jbrink64]

The inner plumbing of the pump can be complex. There are 2 wear plates that squeeze the sides of the gears. Behind the wear plates, there are a series of formed oring seals. High pressure from the outlet port gets behind the wear plate. Pressure pushes the plates tighter against the gears to help efficiency. The orings separate the high pressure from the low pressure side. Small ports are cut into the wear plates to port oil from the seal side to the suction side.

I could guarantee those lip seals would not hold up to 2500 psi without failure.

Shaft seals will let hydraulic oil into the engine, without a doubt. If the hyd level is dropping a corresponding amount that the engine is taking on oil, then a reseal is needed.

 

[jinman]

I took my hydraulic pump to my dealer this morning for a new seal kit. I removed the hydraulic pump this weekend with the help of my grandson. He was a terrific help just handing me tools and even wrenching a few bolts. The pictures attached are a photo series of the process.

Picture #1 is me under the tractor loosening the connection on the suction line so it can be rotated off the pump to allow the pump to move to the rear once it is unbolted.

Pic. #2 shows the pump with the suction side before removal and pic. #3 shows the suction pipe unbolted and rotated away from the pump.

Pic. #4 shows the pump completely removed. It turns out that I could not find my univeral joint adapter for my rachet and could not get to one of the 17 mm bolts holding the high pressure line attached. I had to remove the line from the diverter block and take it off with the pump because I could only get 2 of 4 bolts out of the pump. I also had to remove a bolt in the banjo fitting shown in picture #4 because the pump would not come out without hitting the bolt. The tubing and banjo bolt is in the camshaft oil drain line returning to the engine oil pan.

Pic. #5 shows the pump removed with the drive gear attached and both bearings. Pic. #6 shows the bearings and drive gear removed from the pump.
Pic. #7 shows the whole pump and pressure tube still attached.

Pic. #8 shows the drive shaft into the pump and the external seal. You can see a piece of the seal all blown out at the 10 o'clock position. This seal blowing is a result of the inner seal blowing. Both seals must be replaced for a successful repair.

I should get my pump back by the end of the week. and be ready to reinstall. Hopefull, I can find my 3/8 universal adapter. If not, I'll be buying a new one.

 

[jinman]

Jinman,

Is that a KAYABA Hyd gear pump..??

On the end of the pump is KYB stamped in capital letters. I would say that stands for KaYaBa. I think they are pretty common on compact tractors.

 

[wdchyd]

Jinman,

That same pump was brought in to me a couple weeks ago and the customer broke 2 previous front housings......he was looking for me to weld up the cracked housing which I refused....

Come to find out he boosted the PRV on the FEL controls for more lift capacity and that's what broke his pumps.....He had to back the pressure down to factory specs....but ended up with buying another new pump and saved the others to order front housings for backups......

 

[Eastbx]

Jinman,
Thanks for the lesson. This is some good reading. Very interesting for a novice like myself. :thumbsup: Please post pics when you put it back together.

 

[jinman]

Come to find out he boosted the PRV on the FEL controls for more lift capacity and that's what broke his pumps.....He had to back the pressure down to factory specs....but ended up with buying another new pump and saved the others to order front housings for backups......

I sure understand your position and agree with it. I firmly believe in leaving relief valves right where they are. That just affirms my belief. If I can blow seals with the relief set at factory spec, I don't want to find out what any higher might do. If I need more lift, I'll get my other/bigger tractor.

 

[LarryD]

Well Jim, as soon as I saw your first pic all I could think was you really are a shade tree mechanic.

You bring credit to that heritage.

 

[Elviscaretaker]

Great pictures. Sort of looks fun too.

 

[jinman]

Well Jim, as soon as I saw your first pic all I could think was you really are a shade tree mechanic.

You bring credit to that heritage.

"King of the shade tree mechanics," that's me. Did you notice my "homeboy creeper" made out of an old cardboard box? I have a whole collection of those.:laughing:

BTW: I told my grandson to be careful where he kneeled down with his shorts on. There were young poison oak plants all over the place.

 

[jonyyuma]

Jinman, Shadetree or not, glad to see you did not just load it up and take it in. I have the same creeper type at home for emergency use...Interesting facts about failure of pump seals and or housings breaking due to Boosting pressures..This article took my interest in pushing my pressures---- away...Hope to see you have it back on the line soon..