TW15 Will not move at times.

Good Morning


I have a early model TW-15, 83-85 After it sits for a few days at times it won't move, just lurches ahead a bit when letting out the clutch. At the advice of a couple guys on the general tractor forum I checked the low pressure pump.
What I found was this. Started tractor and I had no pressure, after about 5 minutes of trying to move it suddenly the pressure went to 120 lbs and it moves fine. I get 120lbs at idle and just under 180lbs at 2000 RPM.
So my question is. Could something that drives that pump be failing, or do I have a valve, bypass valve in that system that's hanging up? Or can a failing pump act that way?

Any help would be appreciated, thanks
 
Sounds like an issue in the regulating valve assembly, specifically contamination that is causing the
internal valve spool(s) to hang up. Your description does not fit a typical pump failure scenario.

The valve spools in question are #3 & 5 in the link below. Also check the orifice in the valve body between
the two chambers for contamination as well. The valve body is bolted to the RH side of the transmission case
in the area of the shift linkage.
Spools
 

Good Morning

Well after a tough season (Last summer) and losing two friends. I'm back at this TW15.
After taking Berns advice and checking out the circuit relief valve I couldn't really see anything wrong with it but found a good deal on a new one.
Here's what I've done since my last posting.

Replaced the low pressure pump and relief valve. Under advice i replaced the shaft that runs the pump. I took the suction pipe out and made sure that the screen was clean and replaced the o-ring.
My problem remains. I have 0 pressure on start up and the tractor won't move. Sometimes it takes 30 seconds other times 2-3 minutes. I'm checking pressure at the 1/8 inch fitting by the differential lock on the high pressure pump cover.
Another thing I discovered is I'm getting no oil to the cooler when I do get pressure. As Bern had pointed out with the pressure issue (to check out that valve) this problem also points to that valve. Again it's new so I'm a bit lost. I get about 200 lbs of pressure from this pump. Could it be a volume issue? Another words I'm getting enough volume to feed the pressure system but not enough oil remaining to feed the lubricating/cooler circuit.
Any help would be greatly appreciated.

John
 

Good Morning.

Since my last post I've taken apart the dual power valve, inspected it and replace the o-rings, same with the diff lock valve.
Found no issues and i still have no oil to the cooler and it takes to long for the low pressure pump to give me pressure.
I'm thinking maybe the pick up tube is not seated in the rear of the transmission correctly? I purposely over filled it to insure that the area where they connect is totally submerged with no better results. Not sure if that is a accurate test for a bad pick up tube connection.

John
 

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