John Deere 755 Tractor Transmission Issue

Yourkie · Aug 31, 2020

My JD 755 tractor which I purchased new in Sept 1988 has 1088 hours on it. Today the transmission started to whine more than normal. Tractor moves but is reluctant, and the tractor steering became stiffer (normally no resistance), and steering wheel started to kind of chatter under load too. I'm assuming it must be a transmission issue. The transmission fluid level cold looks OK. Any suggestions on this? I still have loader and mower deck on it. Haven't posted on here for a while.

I was dealing with a health issue and have not been using it much since summer of 2017. Prior to I usually did most of my own maintenance and repair. At that point I had the dealer go over it and do a major maintenance including changing all fluids including trans oil and trans filter and cleaned sump screen. etc. I don't think I put over 5-10 hours on this in 3 years since. Odd I just noticed their invoice for this shows less hours on it when they took it in than what it had. This little guy has mostly been trouble free. Thanks for any help.

CADplans · Aug 31, 2020

The FIRST thing I would look at any quick connects that might possibly be partially disconnected,,
That can cause oil heating, and similar symptoms,, and it is the cheapest thing to check!! :thumbsup: . , ` ~ ,:laughing:

Other than that, the tractor is pretty rock solid (we have an 855) , I would change the hydraulic oil, and filters,,

This can be a suction filter issue, if it has a suction filter?

Yourkie · Sep 2, 2020

CADplans said:
The FIRST thing I would look at any quick connects that might possibly be partially disconnected,,
That can cause oil heating, and similar symptoms,, and it is the cheapest thing to check!! :thumbsup: . , ` ~ ,:laughing:

Other than that, the tractor is pretty rock solid (we have an 855) , I would change the hydraulic oil, and filters,,

This can be a suction filter issue, if it has a suction filter?

Wanted to thank you for the tips. Was wondering if anyone has run into this. Sometimes it is a common easy fix. That x55 series was a solid CUT.

When you say suction filter issue do you mean oil filter at front of transmission (AM102763) The hydraulic oil, filter, "screen" were supposed to be cleaned serviced by dealer about less than 10 engine hours ago (but 3 years ago ) by dealer. The only quick connects I have on this are for the FEL which seem OK. Tractor reluctantly wants to move, power steering stiff and not functioning / chattering, transmission noisy as though it is in relief and fighting itself. the problem started out of the blue. I'll probably end up taking it to dealer. Im not as interested getting under it with a wrench. Looked at hydraulic troubleshooting section in manual.

jd110 · Sep 2, 2020

I am suspecting you may have a suction leak allowing air to be drawn into the system. Check the rubber Manifold at the rear of the tractor #14. I have seen some crack as they have gotten older. Also check hose and hose clamps at lower end of suction tube. Hose #18 and clamps #16. You might also take a look at the hydraulic oil since it has been sitting idle so much. Could have collected condensation from sitting and gummed up sump screen.

Yourkie · Sep 3, 2020

Thanks for the info and parts break out. That really helps. I'd really like to find a good theory of operation on this hydraulic transmission and the configuration. It helps to understand how something works. Here are a couple of photos of the #14 rubber type manifold on my tractor and the lower #18. As you can see they have seen wear. Is it obvious to you that they are a likely source of a vacuum leak? Looks likely to me. I have tightened up the clamps. I had tightened clamps earlier and it didn't make difference.

PS. I thought I had read on a pop up on the JD parts catalog that they were ending that service in 2020. It sounded like they wanted customers to go to dealer. Did I mis-read that? That documentation is an excellent service. The newer version is much better than the old that never made much sense.

Yourkie · Sep 28, 2020

I wanted to close this thread out. The hydraulic transmission problem was due to the sump screen at the rear and bottom being closed up with sludge build-up. The transmission oil had been changed by a JD dealer in Sept 2017 who had completely serviced the tractor and supposedly changed all fluids and cleaned the sump screen. It only had 10 hours put on it since then. Perhaps the sitting caused this sludge buildup because it looked like trans oil fluid was cloudy and may have moisture.