1980 John Deere 401C will not move forward

[patricku421]

Good morning all!

I am working on a John Deere 401C for a friend that owns a feed store and boy does this thing have me stumped! To start off with, I have very, very little knowlage about shuttle shift in general, especially on the older machines. The problem all started a few weeks ago when he was using the machine to run a square baler. He was running along just fine and suddenly he lost all forward gears. The tractor still has all of the hydraulic functions (loader, 3 point, power steering and power brakes) along with all reverse gears, just no forward. I have already cleaned the hydraulic screen, flushed the hydraulic fluid and refilled with hyguard and verified that it is exactly on the full mark at idle. Does anyone have any idea what to look at next?

 

[Tx Jim]

Check linkage from lever on dash to shift valve. Linkage at valve has a history of a pin in linkage breaking. Also check pressure at shift valve. Pressure should be 155-165 psi.

 

[patricku421]

Check linkage from lever on dash to shift valve. Linkage at valve has a history of a pin in linkage breaking. Also check pressure at shift valve. Pressure should be 155-165 psi.

Linkage is all moving as it is supposed to. Forgive my ignorance, but do you have a diagram or a picture that shows the test port location? The shuttle shift on these tractors is totally new to me, but I am trying to help a friend out and save him some money.

 

[Tx Jim]

My knowledge of JD ind tractors is limited as I was formally employed by an "AG only JD dealer" but I think test port is on this control valve on RH side of trans case. It's possible gasket(key 3)has a bad place in it. I suggest you acquire & study a JD ind tractor tech manual.

 

[Zebrafive]

Linkage is all moving as it is supposed to. Forgive my ignorance, but do you have a diagram or a picture that shows the test port location? The shuttle shift on these tractors is totally new to me, but I am trying to help a friend out and save him some money.

System test port is key27, key 29 are test ports for the clutch packs

 

[Zebrafive]

If pressure is not correct you add or subtract shims key 21 (should have 6pc) access through plug 15

 

[Zebrafive]

If system pressure is OK move to the clutch pack test ports.
Make sure clutch pedal is adjusted correctly.
Check clutch pressure. Clutch pedal UP CAUTION TRACTOR MAY MOVE! Move reverser lever to F or R and clutch pressure should match system pressure.

 

[Zebrafive]

It is also possible an internal oil line is broken Key 4 is forward, key 6 is reverse

 

[patricku421]

It is also possible an internal oil line is broken Key 4 is forward, key 6 is reverse

I am thinking this may have been my problem. Once I pulled the control valve off, what appears to be the forward internal oil line was loose and out of place. I assume the only way to replace this, along with all of the o rings is to split the tractor?

 

[Zebrafive]

Yes, you have to split to replace internal oil lines. I would replace the reverse line too.