Deere 670 Hydraulics

[CoyPatton]

Thank you rScotty.

Yeah, thats pretty much what happened. In my case, I believe that the water may have entered the system through a broken rubber hose for the vent on the top of the rear diff/tranny. I have a tendency to store the tractor with the seat up, to keep from getting a wet rear end. LOL. But when I saw that hose, I replaced it right away, but I have no idea how long it was that way.

A cheaper hydraulic fluid for a few hours of work seems like sound advice...as does the cover/tarp.

Thanks again!

I am not against the cover ideal even if the cover is a tarp. However, I suggest several small tarps in key areas. 3 due to water into oils!
1) the gear shift and top of the tranny
2) the steering column as the Yanmar and Yanmar build tractors of this vintage are prone for water to run down the steering column and force the oil out of the steering box
3) the top of the differential/hydraulic housing under the seat.

Small tarps are suggested as tarps over stuff just seems to attract every type of climbing and flying critter to collect under them to build a home.

 

[Edhead]

I am not against the cover ideal even if the cover is a tarp. However, I suggest several small tarps in key areas. 3 due to water into oils!
1) the gear shift and top of the tranny
2) the steering column as the Yanmar and Yanmar build tractors of this vintage are prone for water to run down the steering column and force the oil out of the steering box
3) the top of the differential/hydraulic housing under the seat.

Small tarps are suggested as tarps over stuff just seems to attract every type of climbing and flying critter to collect under them to build a home.

Thanks for the comment. Agreed on the critters - I've got plenty of experience with those. LOL

 

[Edhead]

Everyone - THANK YOU! Last weekend I drained all of the hydraulic fluid from the multiple points. During the week the new o-rings, screen, another hydraulic filter, and another 5 gal of the Hygard arrived. Today, I buttoned everything up, added the HYgard, and low and behold the hydraulic system is functioning like new (including the power steering). I drove the unit around a bit today and cannot believe how solid she feels. Whooo hoo! I do still have a hanging right rear brake to look into, but it looks like the hydraulic issue has been resolved. THANK YOU ALL for the solid advice. After resolving the rear brake issue, I'll put her to work and after a few hours of work I plan to drain the hydraulics again, clean the screen, replace the filter and all of the fluid once again as recommended - need to ensure that any compromised fluid is out of there. This is such a relief - and I cannot thank you all enough.

If the rear brake give me any headaches, I'll post a new thread after searching for relevant information.

Once again - THANK YOU!

Ed

 

[RustyShackleford]

Where did you find a new screen ? I cannot find it in the parts diagrams. Although I'm told you can fabricate your own from stainless 200-mesh hardware cloth.

 

[CoyPatton]

Where did you find a new screen ? I cannot find it in the parts diagrams. Although I'm told you can fabricate your own from stainless 200-mesh hardware cloth.

For forever the go to place for these yanmar built to JD spec tractors was Hoye Tractor in Texas. Unfortunately for us yanmar owners,Aaron decided to retire (good for Aaron and best of all for him).
You can still find lots of parts for Yanmar built tractors through other sources.
Try Yesterday’s Tractors for the screen. It will be located basically in the bottom of the sump. Find your suction tube, then look on the opposite side for a removable plate (Be a while but I believe mine has 3 bolts holding it in place). To control the mess somewhat drain the fluid first.

 

[rScotty]

I just googled "JD 670 Transmission Filter Screen" and got a picture that looks like the one attached.
They are all much the same. Sump filters like that aren't a perfect oiltight fit - the ends of the flter slide rather loosely over a couple of locating projections in the sump. After all, they are only a safety filter for large chunks of crud and designed to be cleaned. Some are nylon and some are metal screen. I've bent them back into shape and even patched them. The problem they cause is that they get completely coated to easily, and not having a bypass valve they then starve the hydraulcs.

The disposable screw-on filter takes care of whatever the sump filter misses. And that screw-on filter does have a bypass valve.
rScotty

 

[RustyShackleford]

I just googled "JD 670 Transmission Filter Screen" and got a picture that looks like the one attached ..

Yeah, that wasn't so hard . Looks like it's $130+ though ...

 

[rScotty]

Yeah, that wasn't so hard . Looks like it's $130+ though ...

You don't need a new one, just clean up the old one.