[73deereh3]

Mowing with my new to me 318 today I noticed that when climbing an incline the tractor would actually slow right down. When coming back down the hill the tractor would speed right up again, almost acts like the trans is losing pressure or something. Anyone know where to start checking for problems??

 

[dkarst]

Typical symptoms or worn linkage parts in hydro control... very doubtful of serious transmission problem if it has fluid and hasn't been very abused as they are very tough. Pull the seat/fender pan and wiggle some control linkages... very little wiggle will cause speed problems you mentioned.

 

[73deereh3]

That's what I was thinking too, we pulled fenders off today and checked some of the linkages out and didn't see much play. I'll have to check into it a little more and see what I find. We were honestly leaning towards the two free wheel valves on top of the trans as they both lose pressure almost immediately after the tractor is shut off. Could these valves cause this?

 

[chuckv]

Andrew,

You don't normally see the wear/slop in the linkages that are more than enough to cause ground speed variation with grade/load. You will need to take the linkage apart to verify the wear. Lots of members here have had the same experience -- no real visible play but worn parts sufficient to cause the variations... A search of the archives with show many pictures of what can wear.

...here are some to review:
Since it takes very little motion at the control input shaft of the hydrostatic transmission to make a very substantial change in ground speed, each little bit of wear in the linkage joints along the way all add up even when you can not "see" the wear/slop. There are lots of threads here about ground speed variation. Here are a few:
http://www.wfmachines.com/discus/messages/335/302749.html
http://www.wfmachines.com/discus/messages/335/250766.html
http://www.wfmachines.com/discus/messages/335/172019.html

Chuck

 

[73deereh3]

Thanks Chuck, Hopefully I get around to taking it apart tonight and Ill post what I find!

 

[73deereh3]

Thanks for your help with this guys. Turns out the tractor had a worn roll pin on the side of the trans. New roll pin and the problem is history. Can anyone give any insight as to how long these onan b43g engines last before needing a rebuild? This tractor has about 2100 hours on the clock and seems to run great with around 95 psi in each cylinder. Just trying to decide if this 318 will be the replacement for my 140 or not!!

 

[deereman84]

Andrew-
At 2100 hours, if the clock is correct, you are close to rebuilding. Many have rebuilt before they get to 2,000 hours. Does is burn much oil? Minimum PSI in each cylinder is listed as 75 PSI with no greater than 10 PSI difference between the two cylinders.

 

[chuckv]

Andrew,

A well cared for Onan can go well over 2000 hours, particularly if it gets de-carboned every 500 hours like the service manual states.

Run them out of oil, and they will last about another 10 minutes...

Chuck