3388 Hydraulic pump

haymaker421 · Nov 13, 2009

Getting ready to replace/repair the hydraulic pump on my 3388 for the third time. Why don't these pumps last longer? I have had IH tractors all my life and the only other hydraulic pump I ever replaced was on an 806 and that was 30 years ago. And man are they expensive! Anyone know where I can get one in good shape that doesn't cost an arm and a leg?

bc · Nov 13, 2009

What's wrong with them when you take them apart? I suspect a problem with the filter and screen and maybe some sludge trapped in the system somewhere.

dwag · Nov 13, 2009

www.hy-capacity. They offer a kit to convert back to the gear pump. I believe a piston pump needs to be fed by a charge pump, which IH didn't use at the time, which caused cavitation. imho

pete 23 · Nov 13, 2009

I think you will find the kit referred to will cost less than a new piston pump. Cavitation is indeed the main problem with that system. Piston pumps do not draw oil well, they need to be charged constantly. You will still use the same closed center valves and be able to control the volume of flow to outlets. Engineering did a quite a unique conversion on this system, using a unloading valve spool in place of the priority spool and it works out quite well.

Anonymous-0 · Nov 13, 2009

A company Allied Precision, makes a filter extension which allows two filters to be used with these and other model tractors.Does anyone think that the increased flow of filtered hydraulic fluid might let the piston pump live a little longer?Just wondering.

pete 23 · Nov 14, 2009

I think the extra filter capacity would be a great idea and should help pump life. That being said, there are a lot of different types of pump failure on these series including the wearing out of the pto shaft spline and gear that drive the pump. Lots of time compensator was the problem, sticky spool. Polished several that would stick when warmed up, cool down and worked ok again. Plugged orfices or blown o-rings. The swash plate actuating piston would also stick in no flow positon. Found a couple of them. If you take the pump apart and the ball sockets are worn on the slipper pivots it is definetly cavitation causing it.

haymaker421 · Nov 15, 2009

Well first about the filter. The 2+2's had double filters anyway on the right side where the other 66's just had one. The first time the pump went out, the splined shaft broke and the same thing happened the second time but this time, though I haven't been able to get under the tractor to remove the pump, it seems that the whole housing has come lose some way or other. The transmission oil has all leaked out through the housing where it bolts to the rear frame.

pete 23 · Nov 15, 2009

On the filters again, the 2+2 used two small filters because the steering pump took it's oil through the end cover so due to this configeration the one large filter would not work as you needed the screen cold oil bypass in between. If you broke the shaft I am almost positive you have a worn out pto shaft and gear also. I have had to replace them.

3388 Hydraulic pump

haymaker421

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bc

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dwag

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pete 23

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Anonymous-0

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pete 23

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haymaker421

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pete 23

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