John Deere 670 with weak hydraulics

[RustyShackleford]

My old (at least 20 years) John Deere 670 Compact Utility Tractor has gotten to where the hydraulics are quite weak. In particular, the Model 60 loader (bucket with tilt and lift) has gotten much weaker than it used to be.

I'm wondering how to fix the problem. Is it likely I need a new hydraulic pump ? There's a new after-market one available here:

https://www.fridayparts.com/hydraulic-pump-am876753-for-john-deere-tractor-3005-4005-670-770-790-870-970-1070

... but I wonder how good its quality is, and how difficult to replace ?

Other factors such as pump adjustment or clogged filter ?

I'm clueless here, and would appreciate anyhelp.

 

[oldnslo]

The first thing to check is the Hydraulic pressure to see what it is vs what it is supposed to be. Then if lower than specified start diagnosis to determine if simple as the relief requires adjustment or something more serious.

Does it lift slower than it used to when empty?

 

[gstrom99]

My old (at least 20 years) John Deere 670 Compact Utility Tractor has gotten to where the hydraulics are quite weak. In particular, the Model 60 loader (bucket with tilt and lift) has gotten much weaker than it used to be.

I'm wondering how to fix the problem. Is it likely I need a new hydraulic pump ? There's a new after-market one available here:

https://www.fridayparts.com/hydraulic-pump-am876753-for-john-deere-tractor-3005-4005-670-770-790-870-970-1070

... but I wonder how good its quality is, and how difficult to replace ?

Other factors such as pump adjustment or clogged filter ?

I'm clueless here, and would appreciate anyhelp.

Fluid, filter (and screen - if equipped) change/flush first. Then check pressure.

 

[rScotty]

Fluid, filter (and screen - if equipped) change/flush first. Then check pressure.

First things first. For hydraulics, the first thing to do on many small Japanese tractors from that era is to clean the wire screen in the transmission sump. Yamar/JDs especially.

 

[5030]

Begs to ask... In 20 years have you ever changed the fluid or filters??

 

[RustyShackleford]

The first thing to check is the Hydraulic pressure to see what it is vs what it is supposed to be.

Does it lift slower than it used to when empty?

Ok, need to get some kind of pressure gauge. Where's a good point to attach the gauge ?

I think it does not lift slower; just can't pick up nearly as much weight.

Fluid, filter (and screen - if equipped) change/flush first. Then check pressure.

First things first. For hydraulics, the first thing to do on many small Japanese tractors from that era is to clean the wire screen in the transmission sump. Yamar/JDs especially.

So it doesn't have a replaceable filter like an oil filter ? Dunno if it's Japanese, but sounds like it probably is. This looks like a spin-on hydraulic filter: Fits John Deere 650 670 750 770 790 850 870 950 970 990 RE27284. But looking at the service intervals (see attached file) it looks like it doesn't.

Begs to ask... In 20 years have you ever changed the fluid or filters??

Uh, I think not, but let me check.

Thanks, guys !

 

[RustyShackleford]

I actually located a 1000-page service manual ! Too big to attach here, even the section on hydraulics.

One question though: they keep talking about the SCV (selective control valve). My tractor has a lever that you can move in four different directions, to raise and lower the bucket, and to tilt the bucket back and forth. That means I *do* have an SCV, right ?

 

[JimRB]

1989-1997 were the production years. Produced in Japan by Yanmar. On my 870 that metal screen is before the metal can filter. You might be amazed at how much junk is in that screen. The small owners manual should have to how to remove info and also mention if you have a can filter. When I say can filter I mean a filter that looks like an oil filter. On my tractor the oil filter and screen are under the left foot panel.

I replace lift arm seals. They fell apart. Not much power when seals are leaking internally.

 

[gengine]

@RustyShackleford Your SCV('s) are the hydraulic ports for 3pt attachments on the rear of the tractor, if equipped. If one of those control levers on the side console are not in neutral, you are losing pressure for your loader. It will be separate lever than your 4 position lever for your loader. It is possible it was used to run your loader, but not likely on that new of a unit.

 

[RustyShackleford]

There's a another sliding lever to the right of the seat that raises and lowers the rear 3-point hitch.