Terex (asv) PT 80 Sluggish drive controls

[zzvyb6]

I'd bet that they changed the oil and put the wrong hydraulic fluid in it or added a quantity of the wrong fluid. Same symptoms occurred with a friends kubota. Corrected the fluid to recommended type and off to the races.

Terex Premium All Season MV Hydraulic Oil
Service Capacity: 12.25 gal.(46.4l) incl. filters

Also check flow in low and high flow settings.

 

[jayburmister]

I finally figured out your problem since I had the same problem with my sr 80. Water is in your hydraulic tank. Your joysticks are hydraulic over hydraulic. Oil does constantly purge through the joystick. It remains stagnant in the line. You need to drop one line at a time in a bucket and flush the dirty oil out. I posted a YouTube video on how to remove water from hydraulic fluid. Search water in hydraulic fluid separation. It痴 not the best video but the process worked and saved me from buying 3-4 oil changes. Just a heads up, the fuel filter/water seperator isn稚 the best. Water in fuel will also jam this up. Use water and slime remover for diesel fuel additive. It will change the water to methenal at any temperature. I have had plenty of problems with this skidsteer and fixed them all. I have been running problem free for a couple hundred hrs now and it outperforms any other machine I致e had.

 

[Yoshiboldor]

Thanks for your interest and help!
I also suspect a charge pressure issue. I have ordered a coupler for the test port and hope to have it before the end of the week to test the pressure in the charge circuit. The manual states that low charge pressure can be the cause of sluggish operation. here is a link to the manual, hydraulic schematics are page 15-20. http://manuals.gogenielift.com/Parts%20And%20Service%20Manuals/data/Service/Terex/IO/2046-310.pdf

What did you find was the problem with this ?? Did you solve it??

 

[Knucklehead11]

What did you find was the problem with this ?? Did you solve it??

Unfortunately, I have not solved the problem, but here is what I know;

The charge pressure was on the low end of normal (reading a gauge installed in the test port) I cranked the posi-power relief valve all the way out and now the charge pressure is on the high end of the spec. This made a slight but noticeable improvement in the control response.
I changed the filter on the charge system....this made no improvement.
The control response "sluggishness" ranges from a minor annoyance when the oil is warm (+60 degrees f) to rendering the machine nearly unusable in very cold temperatures (-30 degrees f)
The slow response is limited to the drive controls, the lift and aux controls are unaffected.
The hydraulic quick-couple is also noticeably slower in cold weather...Both the feed out to the drive joystick and the quick coupler cylinder feed come off the same side of the pilot generation block, making me suspect that there is some type of obstruction in the pilot generation block. This could be foreign material, or perhaps the drive control safety solenoid is not opening completely.
My next move may be to pull this valve, and switch it with one of the others to see if there is an improvement. I may also try disconnecting the feed line at the joystick to see what I get for a pressure reading there.
BTW..it is MUCH easier to work on the pilot gen block by tilting the cab and pulling the footwell, but you will still need access from below..
It would be nice to have a schematic diagram of the pilot generation block, but so far I have been unable to find this...

Any help or experiences that others may have would be welcome!

 

[Yoshiboldor]

Mine is the opposite, when the machine is cold it has drive, but after about 20 mins is looses drive power, the loader seems fine. When it cools it seems to get power back
I haven't checked charge pressure yet, i am planing on buying the fittings to test this today.

Have you tested drive pressure?? This would probably tell you more?