I posted a lengthy description previously but after some more troubleshooting this is what I have found. I have pressure gauges connected to the pump and torque converter (TC) test points with hoses so I can watch them. Several people suggested I had problems with inching valve so I removed the brake line from the inching valve and capped it - opened inching valve and spool seems to be moving freely - left the brake line disconnected so nothing can actuate the inching valve. When first started I have to rev the engine a lot to get it to move in both forward and reverse. Pump pressure 60 to 70 psi at idle - up to 190 psi at full throttle. TC pressure zero even at full throttle. As it warms up the truck shifts into gear more crisply and moves better with less throttle but still slipping some - wont spin the tires if I push against something with the forks. TC still zero pressure. When it is moving pretty good I take it on the driveway and get it moving quickly at full throttle - TC pressure starts to climb to 40 psi as truck gets to full speed. As soon as TC pressure starts to climb the pump pressure jumps up and stays at 150 psi minimum even when I let it idle. Once this happens there is no slippage - it will spin the tires if I push the forks against something solid. TC pressure still zero increase to about 40 psi max at full throttle. Summary - pump pressure stays low at idle like flow is going back to sump and TC pressure zero. Once it warms up and TC pressure starts to climb when driving pump pressure goes to 150 psi minimum at all engine speeds like the pressure regulator valve starts working but TC pressure still zero at idle. I think I have eliminated the inching valve by disconnecting it but not sure what to try next ???
make sure no one has tampered with the valve body and all pieces are intact..usually there is a pair of springs in the valve body that centers the inching valve..if one is missing the valve spool will find it's own center and it may be partially diverting or blocking flow depending..I went thru hell working on one of these until I determined the valve body was tampered with and discovered the spool and missing spring.Went thru two valve bodies until I got one that was good,what a PITA.It sounds like you have good pump flow and possibly a bad torque converter. If you replace the TC be sure to partially fill it with oil before installing it and check oil level when first starting it up after replacement as it fills under operation..Not to start a flame war but dont buy anything from TruPar i went thru a lot of BS with them on my TC core return and they got me for a $250 core even when the one I shipped back was without dents bulges or external damage..its a game they play because they know you wont pay for shipping a 'bad' heavy TC core back to you..beware FWIW
I am having very similar issues with my glp050. I believe my inching valve control body has been gone through before and might be missing a spring. Are there any diagrams available showing this part and what is inside? Also where do you guys order parts from? Seems to be hard to find online? Thinking I may be missing a spring. I only have one spring behind the plunge valve inside the control box nothing on the front side of the valve or in the inching valve body. Thanks for your help in advance
A little more info. I have not done any pressure test yet. My machine shifts correctly and immediately with no lag. When driving in forward or reverse it is very sluggish, will not really climb any incline. Motor will not turn up when on an incline. It will turn up and moves very fast going downhill. It turns up great when in neutral. It does get a little better as the machine gets hot. I guess this is expected but still very sluggish when on inclines. I have blocked the front tires off the ground, motor and tires spin up quickly when off the ground.
Here is the parts list for the GLP050 - the inching valve is parts 21 to 28 and the spring is part 2. PArt 21 is the fitting where the brake line connects.
Thank you. Very helpful. Where did you order parts from? What ended up being the fix to your problem stated above?
Parts were available from the local Clark - Hyster dealer however I never ordered any parts - I wasnt really sure what the problem was and I figured it could be something internal like the torque converter. I didnt want to get that far into it soI ended up selling it as is to someone who had a lot more experience working on them.