Massey 135 Perkins Gas High Idle Issue

[musamisa]

I just bought a 3 cyl gas 135 not running. I rebuilt the carburetor and got it running great with one exception. Before and after the carburetor rebuild, it has always idled around 1400-1500, when it should be at 700-800. The governor works at max rpm and the linkage SEEMS fine. Even though the linkages move freely, they will not let the throttle go down and carb idle screw touch. I've tried adjusting to no success. I also tried setting the governor rod length per the service manual. Any advice? With no return spring, how does this ever return to idle? In the picture, it seems like the bottom throttle rod would need to get longer.

 

[Dieseltech]

The GOVERNOR SPRING makes speed AGAINST THE FLYBALL GOVERNOR. The weights SHUT ENGINE DOWN, the spring CALLS FOR SPEED. The governor to carb rod is CRITICAL to correct engine speed control. If I recall if rod is TOO LONG governor will be lazy, and TOO SHORT can cause a surge problem. Try this with engine OFF, disconnect the carb rod, pull hand throttle wide open. Now set the rod length to JUST match the carb throttle hole with the throttle WIDE OPEN, now SHORTEN the rod TWO TURNS and connect the rod and try again. With engine warmed up, if still lazy shorten it more. If engine surges LENGTHEN the rod a bit. If the weight set in the cam gear is in good shape this will work. If there's trouble inside nothing outside will help.

 

[musamisa]

Thanks. Shortening the governor rod lowered the max rpm, so the governor appears to be doing it's job at high rpm, but it did nothing to change idle. A few questions...With the engine OFF and the hand throttle to idle position, should the carburetor idle screw be touching the carburetor (carb throttle all the way down)? Also, could the high idle issue be a vacuum leak or distributor timing issue? The tractor seems to run smoothly.

 

[Dieseltech]

Thanks. Shortening the governor rod lowered the max rpm, so the governor appears to be doing it's job at high rpm, but it did nothing to change idle. A few questions...With the engine OFF and the hand throttle to idle position, should the carburetor idle screw be touching the carburetor (carb throttle all the way down)? Also, could the high idle issue be a vacuum leak or distributor timing issue? The tractor seems to run smoothly.

Yes, the idle screw should contact the stop with throttle moved forward to idle, at least my Perkins 135 does. If timing is too far advanced engine will run faster than it should. I use an ether can and spray around the intake to check for leaks, if engine speeds up there's a leak somewhere. My 135 only has 2050 actual hours on it with the eight-speed transmission.

 

[musamisa]

Yes, the idle screw should contact the stop with throttle moved forward to idle, at least my Perkins 135 does. If timing is too far advanced engine will run faster than it should. I use an ether can and spray around the intake to check for leaks, if engine speeds up there's a leak somewhere. My 135 only has 2050 actual hours on it with the eight-speed transmission.

With the engine OFF and hand throttle on idle, carb throttle is not down letting the idle screw touch. I will try to see if i can adjust throttle linkage to make this happen.

 

[musamisa]

I'm stumped. When i made that linkage adjustment, I can get from idle to full throttle, but it takes only a half inch of movement on the hand throttle to get there (no good). The fundamental problem is that I have no idea how the linkage ever sits on the idle screw and how the motions are supposed to be.. Does anyone have a video they could post showing how the throttle linkage and governor linkages are supposed to work when the tractor is running?

 

[Dieseltech]

I'm stumped. When i made that linkage adjustment, I can get from idle to full throttle, but it takes only a half inch of movement on the hand throttle to get there (no good). The fundamental problem is that I have no idea how the linkage ever sits on the idle screw and how the motions are supposed to be.. Does anyone have a video they could post showing how the throttle linkage and governor linkages are supposed to work when the tractor is running?

How many hours on the engine? As it speeds up the governor ball weights fly out to CLOSE the throttle against the governor spring. Sounds like there might be governor problems inside the engine.