John Deere 755 crawler

Hello
This is my first time on this site and hopefully someone can help me with my 755. Last week I busted the transmission line coming from my reservoir to the transmission pumps and now only got one track wanting to move. The trans pressure gage will go up into the green until I move it 10-12 ft and stop. I loosen the bleed screws at the pumps but no air will come out of them. With the reservoir cap on it builds all kind of back pressure and it sounds like boiling water inside the tank when the air is released.
If anyone on here can help me I sure would appreciate it.
Thanks
 
Sounds like an air leak on the suction side and fluid level low. Sucking air causing oil to bubble/foam in the
reservoir.

Don't keep trying to operate to correct the problem!
 
Ok Roger I appreciate the advice and I will look at the suction line to see if its sucking air. The fluid level is right at the level mark on the glass. If that doesnt fix it what should I do after that as far as the bubbling in the tank?
Should I put pressure in the tank with my air compressor?
A local guy here said to try that but I dont know if that would be ok or not? anyways Im gonna do what you said to do.
Thanks
 
If memory serves, I think there is a shuttle valve in the control valve under the floorboards that will shut it
down if one side has pressure loss from the other transmission. Did you bleed the transmission control valve ?
It's been so long since I've screwed with one of those crawlers.. You may need to find a tech manual on those
machines. I'll bet it's been 30 years since I've had to turn a wrench on a 750-850 series machine..
 
(quoted from post at 11:17:52 07/11/20) If memory serves, I think there is a shuttle valve in the control valve under the floorboards that will shut it
down if one side has pressure loss from the other transmission. Did you bleed the transmission control valve ?
It's been so long since I've screwed with one of those crawlers.. You may need to find a tech manual on those
machines. I'll bet it's been 30 years since I've had to turn a wrench on a 750-850 series machine..
Hello Roy
Are you talking about the valve that you have to pump up under the floor board ? If so I did pump it up and it did not help. I also bleed the pump bleed screw at the bottom side of the left pump. Its bubbling inside the reservoir and I havent had a chance yet to go take it off yet. Roger said yesterday its sounds like the return line going to the reservoir that creating the bubbles.
He is talking about the big 2 line on top of the pump to the bottom of the reservoir its he ? Im sorry to ask a stupid question like that but Im no hydraulic expert lol . If you can help me with this I sure would appreciate it. Oh I did order me a 755 manual off eBay this morning and maybe that will help some. Well anyways thanks for your input Roy.
 
The valve that you pump up is to release the brakes.. The control valve is sitting directly below the floorboard
right in the center. All the linkages that are operated by either foot pedals or hand controls go to this valve..
This valve operates the steer , direction and counter rotation.
 
(quoted from post at 12:46:12 07/12/20) The valve that you pump up is to release the brakes.. The control valve is sitting directly below the floorboard
right in the center. All the linkages that are operated by either foot pedals or hand controls go to this valve..
This valve operates the steer , direction and counter rotation.
Hello Roy
Yes, I know the valve youre describing. I didnt want to loosen the lines on it because I didnt know if I would make it even worse. should I bleed all the lines going to this valve ? What about the other ones going to the right side drive pump from this valve ? Thanks
 
Oh heck Bobby.. It's been too many years for me to remember, but I seem to think there is a way of bleeding that
valve without breaking lines loose.. I kind of remember putting a clear hose on it and bleed the air out that way..
I'm going to try and find a picture of that valve and get back to you..
 
I wasn't able to find a tech manual for that machine to bleed the hydrostatics.. Tomorrow [ Wednesday] after my doctor appt. I'll slip into the local dealer to see if they can shed some light on this..
 
Ok Roy .Hopefully you can find out something on the 755 at the dealership tomorrow . I really appreciate your time on this problem for me
Thanks
 
.I went to the local dealer today, and they were no help. the individual branches don't want to waste their time on the older machines here. I've got a call into main store to talk to old former employee I had when I was service manager at another dealer.
 
(quoted from post at 20:18:15 07/16/20) .I went to the local dealer today, and they were no help. the individual branches don't want to waste their time on the older machines here. I've got a call into main store to talk to old former employee I had when I was service manager at another dealer.
Good morning Roy ! I just saw your message about you going by the John Deere dealership. Yeah, I kind of run into the same problem with the dealership around here . Put it this way, you get put on hold a lot and nobody has a tech manual for this machine.
I saw on line where I can pay to download a manual for it for 39.99 . I also saw where someone has a original John Deere dealership service manual for sale for 149.00 . Do, you think I should buy the original service manual ? Its a big thick black John Deere Book. Please; Let me know what you think when you get time. Thanks
 
I'm not Roy, but John Deere wants $400.00 for that manual new. If I had a 755 with problems and no manual, I would have bought it, or the other one on eBay, already.

JD wants about $360 for a download or CD. I don't know as I would trust what I was getting with a $39.99 on line download. Some have gotten good ones, some no good.
 
Hello Jim!
I appreciate your info on the 755. I was wondering if it was worth it or not lol. The manual Is the old dealerships service Manual and I think I will buy it.
Thank you sir .
 
Update on John Deere 755.
Roy
I have replaced all the suction lines on the pumps and now I do not have any bubbles or foam in the reservoir now.
I bled both pumps screws with very little oil coming out Of the left pump. I have not bled the control valve that’s under the floor of the crawler because I don’t know what to do. I ordered a service manual but it has not came in yet. I have run it forward and reverse for 10 to 15 minutes with no results. It will move 10-15 ft and it will lock down and go in a different direction . Roy; do you or anyone else on here have any ideal what I should do next to get the left Pump to move ?
I would appreciate any info on this problem that someone could offer
Thanks
 
Good morning Roger
Roger, you told me a little over a week ago that my pump lines probably need to be replaced because all the bubbles in the transmission reservoir on the John Deere 755 track loader.
Well, i replaced all the lines and I don’t have no problem with bubbles or air anymore .but, the left track still want move. I’ve bled the pump at the bleed screw and no air or fluid is coming out. I was told by Roy that on here it has to be bled at the control valve under the floor board. To make a long story short, do you have any idea what I should do? I order me a tm-1137 manual but it hasn’t came in yet. If you can think of anything I would appreciate it
Thanks
 

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