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Gehl 6625 goes forward & backward but wont turn

DeLong

Member
Joined
Feb 14, 2009
Messages
14
Location
Illinois
Great site .Been lurking for a while and finally decided to join.Been around heavy equipment my whole life since my dads a 40 year operator. I dont know a lot about wrenching on these machines but Id like to learn.

Heres the problem. We bought a 1989 gehl sl 6625 with 2100hrs on it last year and ran it for about 50 hrs.Ran great with just a little creep. We figured we'd pull routine maintance on it over winter so I bought the shop/parts/engine manuals on ebay to guide us through it. We changed some hoses to the drive motors,changed planitary oil,chain case oil ,tightened chains, changed hydo and all the filters. We took it outside of the shop to clear some snow and everything was fine.

While we were in fixing things mode my dad wanted to take the creep out of it. He tried to tweak the boost control servos per the manual. Now it will only go forward and backward on the ground. With all the wheels off the ground it turns and does everything fine. We checked the hose routing and its good. I tried to recenter the servos with no improvement. I had a mechanic buddy that works on gehls "a little" set the servos and still nothing.

Any ideas? Sorry for the long post but I wanted to give as much info as possible. Thanks in advance.
 
Last edited:

Construct'O

Senior Member
Joined
Feb 18, 2007
Messages
928
Location
SW Iowa
Occupation
Dozerwork,tiling plus many more!!!!!!!
Might check all your oil levels again after changing out all the hoses and filters when you run it outside you might have gotten all the air out of the system and now are low on oil or might have air locked in the system:beatsme Good luck:usa
 

DeLong

Member
Joined
Feb 14, 2009
Messages
14
Location
Illinois
Thanks. I was hoping that was the case but no such luck. One of the guys said something about a "swash plate" in the tandem pump could be messed up. I dont have a clue what that is but I may find out.:pointhead
 

willie59

Administrator
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Dec 21, 2008
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Location
Knoxville TN
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Service Manager
I'm not familiar with the workings of this machine, which is why I haven't jumped in here. But I think I can say, you ain't got a problem with the swash plates in either of the tandem pumps. If you can go forward or backward, the pumps are working fine, especially if you can push a load, like loading a bucket full of material. I'd say you have a control problem with the pumps, but I know nothing about the components of this machine, not much advice I can offer with this.
 

DeLong

Member
Joined
Feb 14, 2009
Messages
14
Location
Illinois
Thats great advice. I'll look more into the control end of things. No power loss.It will move anything you want it to in this condition.

It just has to be right in front of you.;)
 

DeLong

Member
Joined
Feb 14, 2009
Messages
14
Location
Illinois
Is there any need to bleed the drive motors/hydro system after changing these hoses? If so, how is it done?
 

bill onthehill

Senior Member
Joined
Dec 27, 2008
Messages
661
Location
pa/ny border
If it rolls smoothly forward and reverse for a fairly long distance it should not be air in the drives. my 4640 has a bit of creep when it is cold but will turn fine. does it seem to have good drive power into a pile? I would be looking for a valve that is not reversing. when you had it on the blocks did it have power to both wheels or could you stall one with a 2x4 while the other side still drove. I would be looking for one side with no power in either direction. Bill
 

DeLong

Member
Joined
Feb 14, 2009
Messages
14
Location
Illinois
It goes like heck forward and backward on the ground. Power to both sides doing what the controls ask on the blocks.Try and turn on the ground and it makes a high pitched whine.

I dont know what it would do in a pile.Now Im thinking not good. I did notice today that working the bucket does drag down the forward/backward speed.Seems like it doesnt have enough pressure to do both. Engine is running fine.
 

DeLong

Member
Joined
Feb 14, 2009
Messages
14
Location
Illinois
Well, something in one of the pumps let loose sending metal into the motors. The tandem pump and the motors are off getting rebuilt in a couple of days.I guess theres a lot of flushing involved trying to get the hoses and cylinders cleaned.

Ill reply with the rebuilders findings asap. I just thought Id let it be known what happened since I hate it when threads arent resolved.
 

AtlasRob

Senior Member
Joined
Feb 8, 2008
Messages
1,982
Location
West Sussex UK
Occupation
owner operator
Well, something in one of the pumps let loose sending metal into the motors.

Ill reply with the rebuilders findings asap. I just thought Id let it be known what happened since I hate it when threads arent resolved.

Ouch! that hurts :mad: Glad you found the problem, must admit I was thinking along the lines that probably only one side was driving and miss leading you, :bash

Thanks for the update, I fully agree on your, unresolved, comment. ;)
 
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