Hydro shudder/chatter
 

Just changed out the whole rear end and hydro pump on my 1250. The reason for the change was my hydro pump was leaking from the hydro pump housing itself where the 2 halves go together. Thought it would be easier to change out the whole business. Don't have any experience since it came from my 1450 parts tractor that I have driven very little.
Everything went well in the change and even put on a new cub filter, new trunion springs and lubed up the hydro plates for hopefully a smooth drive. This one seems very strong in the drive department, it's not a lazy hydro pump. Used it today for the first time to mow an acre and a half and it seems to shudder or chatter a little bit going up the slight grade in the yard. Does go away if I change to a faster speed. Seems like it my be slipping a little. I find it hard to believe as robust as it seems to be. Noticed it more when it got warmed up. The hydro fluid I did not change, just topped off with generic brand fluid. The color of the fluid was kind of yellow/green not clear. What do I do to remedy this? Change the fluid? Switch over my valves? Or change to another pump?

I'd swap the relief valves. Good chance that's the issue.

That would be an easy fix. My valves are near new in the old pump. I'll give it a try. Any other input would be great

I'd also change the fluid. That may help also.

My humble 1/50th of $1.....

Change the relief valves and drain old fluid, put in new Hy-Tran.

Sorry for the delay in getting back to this thread. First time I have had to work on the tractor. Switched the relief valves over from my old pump to this one and mowed the grass again. My observations are that when it is cold for the first 5 to 10 minutes of mowing everything is fine then as it warms up, it starts to do the chatter thing. It only does it at one speed going up a slight incline. If I give it more or less ground speed it goes away. Next thing is changing the fluid I guess. Anymore thoughts?

Not until the fluid is changed. Make sure you use the correct filter. :beerchug:

I agree with everyone esle. change the relief valves, and change the fluid and Filter, using the correct hydraulic filter. Use Hytran..it works!

When you say the oil is a greenish color and that makes me think its quick lift hyd oil the oil that is made by the devil. We just had a sprayer come into the shop that would not maintain speed. And would be jumpy. We found it had quick lift oil in it. We flushed about 20 gals of oil through it and filled it with the proper oil and now it works fine. You can use what ever oil you want but I would not use quick lift oil.

Ahh. I hope that is it. I have some Farm & Fleet generic oil made for Case/IH that I have used before with success in the garage that I am thinking of using. The question is how thorough do I have to be in getting all that stuff out of there? I don't have another rear cover gasket on hand. Was thinking of taking the fill plug out and using a suction siphon to set the fluid out while lifting the front of the tractor up in the air. When the rear was installed last week, I did put a new Cub brand filter on it at the same time. Was not going to change it again yet. Do you think that would be adequate doing it this way? Thanks for all your help!! There is a lot of experience here on the forum to keep these alive