Exploding Hydraulic Pump

All,
I am new to the forum. My 1952 8N has blown up the hydraulic pump twice now, following my replacing the pump guts (both valve packs, pistons, cam bushings). The pistons were ripped to pieces, the cam bushings worn to a frazzle and broken, and the second time the hydraulic fluid had huge amount of powdered brass throughout. I did not allow the pump to 'center' prior to tightening the pump to the tractor in either instance. Is this enough to cause the problem, or is there something else?

Thanks

Hi Mark, welcome to the forum. You didn't say if you found water in the sump. If it freezes and you try to run the pump, that will tear things up. Other that that, the others may have more suggestions.

(quoted from post at 13:52:22 11/19/20) All,
I am new to the forum. My 1952 8N has blown up the hydraulic pump twice now, following my replacing the pump guts (both valve packs, pistons, cam bushings). The pistons were ripped to pieces, the cam bushings worn to a frazzle and broken, and the second time the hydraulic fluid had huge amount of powdered brass throughout. I did not allow the pump to 'center' prior to tightening the pump to the tractor in either instance. Is this enough to cause the problem, or is there something else?

Thanks

Click to expand...

That is a lot of damage across a lot of parts and I doubt it's from centering. Is there any oil inside the pump when you tear it down?

TOH

No water. Second time pump exploded just a few hours of running time after I had put some of the original parts back in. Same issue, pistons broken into small pieces, cam blocks mashed up bad. One of the valve packs (one of the originals) had a corner broken off and valves and springs exposed. This had to be mechanical damage, not over pressure.

Sorry not used to system. Hydraulic oil was full. Lots of bushing shavings, almost a powder, in the oil, clearly a sign of wearing of parts.

If I am understanding correctly you rebuilt the pump twice and each time it blew apart. Maybe a suggestion if it is a mechanical failure.....

Shop manual:
Note: The pistons on the scotch yokes are off center. Position the scotch yokes such that the pistons are at the closest position to each other. The recessed end of the cam is installed to the rear of the pump and fits over the shoulder of the power take-off bushing.

I know there is a popular video out there that if you do exactly as the video shows you will assemble the pump incorrectly. The scotch yokes will assemble incorrectly if you are not careful.
JB

Thank you. I just looked at my broken scotch yokes and the pistons are slightly off center, as you noted. I was not aware of this, and I'm sure that at least one if not both of the pistons were off when I rebuilt the unit. That accounts for the huge damage. I will put this together correctly this time.

Any suggestions on how to get the minute fragments of brass out of the hydraulic system? it is deposited wherever the hydraulic fluid settles. I do not have a parts washer or any special cleaning equipment.

Thanks much

I was probably given fifty different suggestions from fifty different owners on cleaning the common sump, Trans, Hyd, Diff.

To become acquainted I made my mind to go as per pictures..

Before I removed AXEL housing, I drained all OIL...added Diesel fuel.. inserted 1/4" steel line into top of Transmission..added 15 psi of air and agitated Diesel . Drained Diesel and repeated procedure.

I'm satisfied with the end results

Bob...Owner 2-N

(quoted from post at 08:54:31 11/20/20)
Thank you. I just looked at my broken scotch yokes and the pistons are slightly off center, as you noted. I was not aware of this, and I'm sure that at least one if not both of the pistons were off when I rebuilt the unit. That accounts for the huge damage. I will put this together correctly this time.

Any suggestions on how to get the minute fragments of brass out of the hydraulic system? it is deposited wherever the hydraulic fluid settles. I do not have a parts washer or any special cleaning equipment.

Thanks much

Click to expand...

Garden hose and some Gunk SC mixed with diesel. Brush or spray the Gunk on, agitate with a parts cleaning brush, and flush with the hose. Repeat as needed.

TOH