C-120 Auto No Reverse

[Tom Rochon 3]

I grew up on and learned how to drive on my Dads 67 Wheel Horse. I have a C-120 Auto that runs mint, but no reverse.  I changed the filter and fresh 10-30W oil and made sure the hand push valve is closed.  Tractor is a type  10491 serial 119527. Transaxle is a Sundstrand 90-1136 serial  03-PD 22618.

 

i have no history this tractor. The guy I bought it from said it didn’t run. Ran some emery cloth through the points adjusted them and this thing runs like new.

 

recommendations are appreciated.

[gwest_ca-(File Mod) 12,178]

Welcome to Red Square.

Here is a link to 24 subjects on your model and they in a random order.

https://www.wheelhorseforum.com/search/?q=1-0491&quick=1&type=downloads_file

[pfrederi 20,365]

welcome  

This manual may help click on the picture. It has good diagnostics.

 

 

[953 nut 65,503]

There is a plastic cam plate that connects the motion control lever to the Sundstrand transmission motion control. They6 tend to become worn and I would start by looking there.

[Tom Rochon 3]

Hello, it's me again. I downloaded the manual you guys sent me, but my unit does not look like the one in the manual.  I drained the unit overnight by removing the filter and drain plug. I removed all valves, inspected them and put them back in the same place just as they came out.  I replaced the filter with a NAPA 1410 filter and 10W-30 oil. I removed the plastic cam so I could move the valve by hand.  Now I don't have forward or reverse. What did I miss or do wrong?  Thanks for all your help!

[pfrederi 20,365]

From the picture you have the piston to piston unit. Which the manual covers. Can you push it with tow valve closed

[Tom Rochon 3]

Hello, I drained the fluid (10W-30) last night and a lot of micro air bubbles came out with the oil.  I cannot push the tractor with the tow valve closed, or open. I noticed (see pictures attached) that there is a flat spot on this bullet. Does this have to align a certain way with the flat surface on re-install?

[ineedanother 2,152]

1 hour ago, Tom Rochon said:

Hello, I drained the fluid (10W-30) last night and a lot of micro air bubbles came out with the oil.  I cannot push the tractor with the tow valve closed, or open. I noticed (see pictures attached) that there is a flat spot on this bullet. Does this have to align a certain way with the flat surface on re-install?

 

If I'm not mistaken, I don't think there's any need or way to align that. The flat side just allows fluid to pass, not intended to hold it in a specific orientation to the motor housing.

Edited 6 hours ago by ineedanother

[ineedanother 2,152]

On 5/2/2026 at 3:47 PM, Tom Rochon said:

Hello, it's me again. I downloaded the manual you guys sent me, but my unit does not look like the one in the manual.  I drained the unit overnight by removing the filter and drain plug. I removed all valves, inspected them and put them back in the same place just as they came out.  I replaced the filter with a NAPA 1410 filter and 10W-30 oil. I removed the plastic cam so I could move the valve by hand.  Now I don't have forward or reverse. What did I miss or do wrong?  Thanks for all your help!

 

It's likely that there just isn't any oil in the pump if you filled it through the filler tube into the gear box. When the system is empty, I much prefer to remove the drive belt and run the drive pulley with a drill and 7/16" socket (in reverse) filling through the top port on the pump housing (11/16" plug at the top of this photo). If you're not turning the drive pulley with the drill, oil will not go in. That will fill the pistons in the pump and motor.

[Bar Nuthin 2,351]

On 5/2/2026 at 3:47 PM, Tom Rochon said:

Hello, it's me again. I downloaded the manual you guys sent me, but my unit does not look like the one in the manual.  I drained the unit overnight by removing the filter and drain plug. I removed all valves, inspected them and put them back in the same place just as they came out.  I replaced the filter with a NAPA 1410 filter and 10W-30 oil. I removed the plastic cam so I could move the valve by hand.  Now I don't have forward or reverse. What did I miss or do wrong?  Thanks for all your help!

 

 

Is it just me, or does something look amiss here?

 

[Bar Nuthin 2,351]

These are the charge valves mentioned in the trouble shooting chart.

There shouldn't be anything in the front one - the back one should have a spring and a metal cone. Make sure the cone is clean.

 

 

 

[ineedanother 2,152]

32 minutes ago, Bar Nuthin said:

 

Is it just me, or does something look amiss here?

 

Without question. Good catch.