[Food plots]

I have not been on here for a while. I do periodically check for possible solutions to issue I am having with my ‘72 646. I was having hydraulic issues, leaking cylinders, hoses and valves. I have taken care of those, I changed oil and yes 15W40 several times. I started having travel issues, put in a updated banana plate, adjusted linkage, new spring and ball in TCV. I can only get 900 psi while adjusting TCV. Found hole in metal pipe sucking air so I installed a new hyd pump from Grainger with same results. It will travel normal for 10 - 15 min then barely move, fwd/rev. I can’t even push with the bucket down on the ground. I have put things in the bucket by hand and lifted a 5x8 box blind no problem. My guess is I have a bad hyd drive motor. Havent seen for sale for a while. Any help would greatly be appreciated. Thanks

 

[Ben L.]

Both hydraulic circuits are only getting 900 psi? Or just drive circuit?

 

[Food plots]

I only tested on the port at the TCV.

 

[Harry]

Have you tried to get the travel relief valve to squeal yet?
Keep the Peace
Harry

 

[Food plots]

No when I tried adjusting the pressure relief valve the highest pressure I could get was 900 psi. I had the tractor against a tree, the tires spun a little bit. It never squealed.

 

[sdunt]

Just to cover the basics.. You replaced the pump, but did you replace ALL of the rubber hoses from the reserve tank. When the tractor is running and you look into the recovery tank is the oil clear, or are there bubbles in it?
What SIZE of pump did you put in ?
There are two pressure adjustments on the TCV, are you adjusting the correct one: Performance of 644lbh & 646 That WHOLE thread is applicable to this question.

 

[Food plots]

4F667 same pump that it originally had, the tractor has a Vanguard 18hp motor. I did replace hoses on tank with new clamps, the seams on tank were leaking, had it brazed. I do see bubbles in the tank.

 

[Food plots]

I adjusted the pressure valve on the left looking at it from the rear of tractor

 

[sdunt]

When I have worked on TCV's you really need to have them out of the tractor to put the relief ball, follower and spring into them. The ball can fall out of place before you can get the follower and spring in there. So its possible that you are not hearing a squeal, because there is no ball in place to 'pop' and squeal.

I discovered this situation when I was adding a TCV as a PTO valve on my 646, I swapped out the ball and spring while the valve was mounted and after that I could not get pressure. Once I pulled the valve, and while I had it mounted in the vice rear end up, then I dropped the ball and follower in from above. So things were in the right place.. Now the relief works correctly.

 

[Food plots]

I did have the valve out, the original spring was bent inside and I had to take it to a hydraulic repair shop to get it out. The ball and spring were put in before being reinstalled. I guess I will remove it again and check. Thanks