Tellite 756 -- Tractor Vet or anyone else....Long

Posted a couple of months ago that the low side is out of my T/A in my 756. High side is very strong. Thought it might be adjustments. Had time to check things out today. I noticed the Tellite never came on at all since I got the tractor in April. Today checked the bulb and replaced it and light works good now. Also added 1/2 gallon oil to the trans. to bring it to the full mark.The problems are as follows:
Start the tractor with T/A back. Let the clutch out and the light goes off if you run it at 1000 rpm or higher. Step on clutch again, lite comes on and won't go off until 2000 rpm or so. Move the T/A lever ahead w/ clutch out and the light comes on and won't go off until you rap it up to 2200 or so. Steering is hard unless you are moving. As you turn the steering whell the lite flickers some but stays on unless you kick up the rpms. The right hyd lever has a power beyond valve on it so the loader can be ran off it. Right now I have my mower hooked up and both hoses of the loader are unplugged inorder to us. the two cylinders on the mower. Could there be a pump/pressure problem indicated by the lite? Could this be related to the lower side of the T/A being weak? I was going to try and adjust the dump valve like Trctor Vet said by watching the light. Didn't figure that would work right now. I changed the trans filter when I got it and didn't see anything to be concerned about.
thanks Dan

You have two issues, one hydraulic and one mechanical. The low side of the TA is mechanical. With the exception of a few "Spragless" TAs made by Hy-Capacity in the late '70s - early 80s, any TA that slips on the low side has an over running clutch failure. On the hydraulic style like you have the hydraulics can offer some assistance to the low side clutch but when the sprag fails they will slip.

Other than sharing a common sump and filter, your 756 has two separate hydraulic systems. The rear pump provides oil for the hitch and auxiliary valves. The front pump provides oil for the controls and lubing the transmission and differential.

The symptoms you describe indicate a loss of flow from the front pump. I do not think that air entering the system is causing the problems. If it were you should have noise and a few other issues. The loss of flow could be a result of a worn out pump but other causes may be a blown O-ring between the MCV assembly and center section or a problem with the flow divider valve. Your tractor calls for a pump rated at 9 GPM at rated engine speed. The flow divider splits off 3 GPM for the steering and other controls and finally TA lube. The indicator light is monitoring the TA lube pressure. When it is on it indicates that there is not enough flow to maintain minimum pressure. The other six GPM goes to the oil cooler and then returns to lube the range transmission and differential. The 3 GPM for the steering and controls is priority so the flow is designed to remain constant. The flow through the oil cooler will vary with engine speed. If the problem were to be found in the TA or brake controls you would not have any steering problems.

I would pull the MCV and check for blown gaskets and O-rings and then check the flow divider and orifice. If that all looks OK it is time for a new pump.

Well , the dump valve maybe sticking or ya may have either a blowen gskt in the MCV or a blowen or missing O/ring in the MCV . If you plan on playen with the DUMP valve then do a full adjustment of the clutch and trans brake also starting off with the free travel on the clutch pedal first then the trans brake . If the steering is weal then you are also having a loss of pressure as it all runs off the MCV pump and NOT the rear hitch pump.as to nailing i down over the magic box that ain't ah going to happen I myself Pete or Owen would have to do some pressure testing and a flow rating of the MCV pump would tell us a lot more. Now we could take a chance and tear into the MCV pump and see what is going on there with a new Gskt. and seal kit and a new spring kit and may help some and maybe a new pump if needed , But that will not cure the low side issue only a new T/A unit will solve that and since you there ya might just as well put a new clutch and PTo input to her and be done with it . It only hurts for a little bit when ya write the check.

Thanks for the info. I figured I'd better get a new t/a in it this winter if I can make it last that long. Dan