IH 756 Diesel

[beef88]

The IH 756 diesel still has the nagging problem of running ruff or loping when I let out on the cluch to move the tractor. It will also do this sometimes just sitting at an idle. I've changed fuel filters and also have cracked all the injector lines one at a time. All have fuel. Any help is appreciated

 

[DeltaRed]

I would say you have a governor/pump problem.Either live with it,or pull pump and have it rebuilt.If it were mine(I too have a 70/56 german diesel)I would wait.

 

[kub6040]

Delta red is right if you leave it and run it it will eventually need a rebuild you have early warning signs .

 

[Highwayman]

Longer you wait the more it's gonna cost

 

[pete 23]

I ran into one of them and replaced the head. There is a check valve in the governor circuit (has hydraulic governor) that either gets some tiny bit of crap under it or just the seat gets beat up. In those days it was not a serviceable item but I believe it is now. It probably won't show up on a test stand though. The original fuel filters on the 706 D-310 engine was made of ( I'll call it horse hair not knowing what it actually was) but they claimed that tiny parts of that was getting through and causing the problem. They quickly went to a paper style filter. Later on it was decided that the check valves were actually wearing also and the ball did not always seat. If you would read the book on those governors you would see why a leak in the control side circuit would cause a problem and then you will wonder how they ever actually worked as well as they do. No easy cure though but I would talk to a good pump man before I tore it off to see what he thinks. One with lot of experience on those pumps. You have to realize the problem I am talking about took place in late 60's, long before most pump men were even around. The engines would just take off and then slow back down. Maybe do it once a day, or maybe every time you throttled down as a slight change in fuel delivery at idle conditions is much more noticeable than under a load.

 

[Dieseltech]

A BIG Xs two what Pete said!! Bosch did say at service school once that "SOMETIMES" several sudden accelerations "MAY" clean/ reseat the check ball. Special tools are used to drill out the small retainer to replace the spring and ball, but if the hydraulic head area where the ball sets is worn much that may not help either. VA models AR, BR, and CR use the same system. Sure like the mechanical VE much better!