601 Hydraulic symptoms?

Looked at a 641 yesterday, the lift was almost vibrating while lifting, almost a clatter it was that pronounced. I don't have my manual with me here at work but I am thinking the only thing in the system that would cause pulses like that would be the pump right? The pump was not making noises as I have heard with some.

I have yet to rebuild one of these, looks fairly straightforward am I right? My Dad had to put a new bearing in one and that was a bear.

So, is this a pump symptom? Thanks

If my lift clatters, I bleed the air from the pump and it works fine.

Should be a pipe plug in the top side of the Hyd. Pump on the right side of the engine.

Of course you might not want to fix it while you are trying to negotiate price....

Others might now other causes for chatter.

Pump was slow to start so it may be losing it's prime and sucking air somewhere, if what you describe is the same, that could be the culprit? Fluid was a little milky so there is that too, but I haven't experienced that in the past with water in the system.

Can't claim the credit on this one, Tony Jacobs told me there is a 2 way seal that is on the shaft of the hyd pump, it seals off hyd fluid from the engine and engine oil from the hyd pump.

He said if that seal is loose or leaking a bit, it can allow air into the system.

Up side, its not hard to change.
Down side, it only comes in the pump repair kit..

Tony, Ken, Adam, Sean, TOH, Soundguy, and a ton of other guys here have been loads of help to me while working on my tractor, just trying to pass it on.

What you are describing sounds like a suction side air leak to me. You need to verify that before moving forward. Try bleeding the pump, if that helps you have found the problem. If you want to get more creative, plumb in a clean plastic tube from the bleeder hole to the sump fill hole under your seat. Run the tractor, if you see bubbles you have have a suction side leak. If the bubbles keep coming you have the cause for the jerk hydraulics.

There are two primary reasons for a suction side leak. You could have a leaking ring seal on the manifold. You might get lucky and that is it. But more likely, the seal in pump is shot. Probably the shaft on the pump wobble shaft is worn also. I would plan on replacing both if that is the case.

The problem with the pump rebuild is that to get the seal out, you have to remove the pump bearing cup from the housing. You usually trash the needle bearing doing that. The main pump bearing is pressed on the wobble shaft and if you replace to wobble shaft, you will need a new bearing here.

I would plan on the following.
1. New wobble shaft
2. Bearing, cup and cone.
3. New seal
4. Needle bearing

The pump rebuild kit usually has the seal, but not the bearings. This kit address the check valves and is probably worth the effort.

If you plan to do this rebuild post back and we can help. It will take a press to install the bearing and some creativity to get the bearing cup out of housing.

Keep us posted.

That's a helpful answer, thanks!