Antique hydraulic system quit - how to diagnose

[J_J]

You may have worn a groove in the shaft where the seal sits.

With the seal off, run your thumb nail along the shaft to check.

 

[lhfarm]

Am I just wrong in thinking the problem may be in the control valve? The seal blows whenever the heavy plow is lifted and remains lifted. If the control valve is not working correctly, could that result in the pump continuing to build pressure until something gives? I guess I'm going to have to figure out a way, to replace the control valve, at least temporarily, to eliminate it as the problem. There isn't a simple way to do that because of the location of the reservoir and control valve are located under the body of the jeep.

My other alternative is to try a different pump. My concern is that if it is the control valve, I could end up ruining that pump too.

Perhaps I need to do some reading on how simple control valves work....

 

[oldnslo]

Am I just wrong in thinking the problem may be in the control valve? The seal blows whenever the heavy plow is lifted and remains lifted. If the control valve is not working correctly, could that result in the pump continuing to build pressure until something gives? I guess I'm going to have to figure out a way, to replace the control valve, at least temporarily, to eliminate it as the problem. There isn't a simple way to do that because of the location of the reservoir and control valve are located under the body of the jeep.

My other alternative is to try a different pump. My concern is that if it is the control valve, I could end up ruining that pump too.

Perhaps I need to do some reading on how simple control valves work....

Since we don't know how your control valve works it is possible. A couple of questions on the failure.
1) When lifting the plow do you here any change in noise from the hydraulic pump especially once the plow is fully lifted? If yes then you are potentially still building pressure.
2) Does the failure happen after you lower the plow and then try to raise again? (I suspect yes since since how would you raise it again)
3) Could the problem be when lowering the plow you get a sudden rush of oil back to tank and the reservoir vent isn't large enough or partially plugged. This causes pressure to build up in the reservoir and blows the shaft seal. Long shot since I would expect the reservoir to burst before the shat seal failure.

Internet diagnostics is sure a guessing game..

 

[wdchyd]

The symptoms you describe I've seen worn out pumps do exactly the same......many times

when cold (first started) they pump barely enough to work, then as the pump warms to operating temp there is too much wear and clearances in the pump....leading to less pressure the more you run it.....also revving is another sure sign of a bad pump

Flow/load meter will prove this beyond doubt

^^^^^^read this

 

[lhfarm]

Since we don't know how your control valve works it is possible. A couple of questions on the failure.
1) When lifting the plow do you here any change in noise from the hydraulic pump especially once the plow is fully lifted? If yes then you are potentially still building pressure.

The pump runs off the crank shaft and I can't hear it over engine noise.

2) Does the failure happen after you lower the plow and then try to raise again? (I suspect yes since since how would you raise it again)

My son and I rode up/down on the lift before attaching the plow. We didn't continue to hold the lift in the up position with out weight. Both times we have attached a plow, raised it, moved the jeep, then lowered the plow, the pump failed (wouldn't lift the plow again).

3) Could the problem be when lowering the plow you get a sudden rush of oil back to tank and the reservoir vent isn't large enough or partially plugged. This causes pressure to build up in the reservoir and blows the shaft seal. Long shot since I would expect the reservoir to burst before the shat seal failure.

The system isn't vented. The only possible way to add a vent to the reservoir is to put a pipe extension on the fill opening. In this drawing http://farmjeep.com/img/newgren_instructions/diagram4.jpg you can see the reservoir as it sets under the jeep bed. The filler pipe is accessible at the back of the jeep.

Internet diagnostics is sure a guessing game..

^^^^^^read this

Showed this to my wife who said "Takes instructions - eventually." Think I'm going to try a different pump, although I'm not sure it is working. There isn't a local shop that works on pumps, but if it leaks, doesn't work, might try to get it repaired, since it is supposed to be NOS.

Thanks to everyone for putting up with my slow learning curve.

 

[wdchyd]

Make sure the rotation is correct on the replacement pumps you are using......wrong rotation can blow shaft seal easily (or severely worn pump)

 

[J_J]

I would recommend having the pump tested by a hyd shop.

If you need a cheap valve , Surplus has a cheap log splitter valve that will work.

20 GPM 1 SPOOL SPEECO LOG SPLITTER VALVE

 

[lhfarm]

I would recommend having the pump tested by a hyd shop.

If you need a cheap valve , Surplus has a cheap log splitter valve that will work.

20 GPM 1 SPOOL SPEECO LOG SPLITTER VALVE

J J,

The only repair shop is an hour away and they don't really seem interested in non-commercial jobs. Guess they have enough business. The last time I took anything there it was weeks before they even looked at it and then told me it was worn out and they couldn't find a replacement. That was when I did the research and found that the pump was the same as used on the IH-C. So I purchased the current problem pump off of e-bay. Very possible it is worn out too.

But maybe I should try to take the NOS pump there for testing and see what happens. A "new" IH-C pump is in the $500-$600 range and I'm trying to avoid that.

 

[J_J]

There are lots of repair shops on the Internet but there is shipping to add to the process.

If you can get the tractor to any hyd shop, they should at least do a flow and pressure test and determine the condition of the pump.

What the flow and pressure test is designed to do is to see if the pump is pumping at least 75% or rated flow and pressure. . That test should be about $45 to 60 in labor.

The alternatives is a used pump , rebuild the pump, or a new pump.

 

[lhfarm]

Removed the coupler from the pump shaft and the seal was blow completely out of the pump! The first time I thought I hadn't seated it properly so was careful with this seal, but this time the seal could be pushed around with my fingers.


Hard to tell from the picture, but the red is edge of the seal. I'm assuming the excess pressure just pushed the seal out. Going to have to figure out how to put in a different control valve (after the weekend show).