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7720 hydrostat problems

9327 Views 3 Replies 4 Participants Last post by  brickwalker
Have an 88 model titan ll with 5500 hours. The hydrostat was replaced 2 seasons ago with a rebuilt one from worthington. Seems to be getting very weak again already. Plan to change the filter tommorrow, but not very optomistic. this never seems to work for us. It seems to act different this time though. when you first push the lever forward or backwards it doesn't want to move at all, but then once it builds up a little momentum it seems to lunge forward.
the hydraulic belt tensioner seems to be working fine. Could it be the surge pump? and if so is there any way to tell without pressure testing?
the machine has a factory 4x4 option. I have been told the hydros last forever on these, except for the ones with four wheel drive.
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I'm having a hydro issue on my 6620 titan II also. My ground speed slows way down when on a grade, especially on the road. JD service guy put in a new forward relief valve (after much pressure testing). I'm gonna have to have him come back out and put some more shims in it though to bring it all the way back to normal.. He did tell me that he'd been working on Deere's for 18 years and only had to replace 1 hydro. That was a new machine and the hydro was factory defective.
How did yours act before it was replaced before?

Maybe Jacob will lend you the money to buy a new combine, since that's his solution to the problem....

We had a 6620 that did the same thing. The first time, it was the hydrostat ; but seems like the second time things acted up, it was the charge pump. I, too, have heard that 4x4's are more prone to hydro. problems than the others.

I would get a pressure test done before doing anything else. Sounds like once it builds up pressure, it wants to go for ya'.
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