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John Deere 670A Motorgrader transmission issues-stops moving after a few minutes

beav

Member
Joined
Sep 13, 2015
Messages
22
Location
san saba tx
Can anyone tell me what is causing motorgrader to stop moving shortly after starting and running a few minutes? The transmission pressure gauge show zero.

Any help is very much appreciated....!!!!!

Paul
 

beav

Member
Joined
Sep 13, 2015
Messages
22
Location
san saba tx
Yes..!!! I've drained the hydraulic reservoir and the clutch pack. Poured 5 gallons of Barsol through reservoir.Cleaned sump strainer. New transmission filters. Filled with new hydraulic/transmission oil. Started great and transmission pressure and transmission lube gauge working, hydraulics working. Started driving down the road, then stopped moving and lost hydraulics and gauges went to zero. You can turn machine off for a few minutes, restart and it would move for a few feet then stop again
 

AndrewC

Senior Member
Joined
Feb 2, 2013
Messages
458
Location
Miles away
So this machine uses transmission oil in hyd system so it has to be something common with both systems. Now there is a engine disconnect on these so start there make sure it isn't engaged. The next logical place to me would be to check the transmission oil pump by putting a gauge into the trans circuit. After that there are a couple regulating valves. How did the oil look? Did you cut the filter open and see how it looked?
 

beav

Member
Joined
Sep 13, 2015
Messages
22
Location
san saba tx
No didn't cut filter up, but cleaned up sump screen.... Full of friction material
 

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beav

Member
Joined
Sep 13, 2015
Messages
22
Location
san saba tx
Oil wasnt too bad... Maybe a little milky. Machine hasn't been started for a couple of years.
Don't have gauges nor expertise to do checks, so probably gong to have to get a field tech to come out to ranch.
 
Last edited:

AndrewC

Senior Member
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Feb 2, 2013
Messages
458
Location
Miles away
I think you'll be doing a transmission with that much material. Probably a pump or your losing too much oil through the clutches. Might want to start looking for a used one to save on rebuild.
 

mg2361

Senior Member
Joined
Jul 5, 2016
Messages
5,057
Location
Pennsylvania
Occupation
Equipment Mechanic
Check that screen again. It may be plugged again because it is very difficult to get all the material out of the sump. I agree with Andrew in that it is too much material. The clutches are obviously whooped:(. If the oil was milky like you said then that could have been the cause of your clutch degradation. Starve the transmission pump then you lose hydraulics because the transmission pump charges the hydraulic pump. If screen is clean then it is probably excessive leakage in the transmission circuit and pressure/flow testing needs to be done to confirm.
 

mg2361

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Jul 5, 2016
Messages
5,057
Location
Pennsylvania
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Equipment Mechanic
Oh crap. This is an old post. DUH:confused:!

What line is that screen in?

I believe it will be the right side of the transmission near the filters. There will be a casting (screen under this casting) with two bolts holding it to the case with a steel tube coming off of it.
 

Auctioneerhere

Well-Known Member
Joined
Jan 26, 2009
Messages
138
Location
USA
I took the line with the two bolts off on the opposite side of the filter side, Noting in the line there. On the filer side I took out a plug with a 1/2 inch ratchet & found a large plastic screen. Mine was not clogged or dirty. I am guessing someone had changed it out or cleaned it before I got the grader.
 
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