Scary Ride today on the B275

Bart Hull · May 22, 2014

Mowing the lawn with a 5ft brushhog, running 3/4 rpm (no tach) for 3 or so hours. When I tried to reduce RPM with the throttle it wouldn't come down, even pulled kill cable, no dice. When I pulled PTO out of gear it sped up more. Finally had to re-engage PTO, put in 2nd Low and drug the brakes to load the engine and then was able to reduce RPM and then kill the motor.

Strange. I fired it right back up did some more mowing and was able to reduce throttle and kill as normal.

Wasn't running hot, it was in the "Run" zone on the temp gauge but it is a 104 degree day here in sunny Arizona. I've been flushing radiator out as it has lots of crap in it and just changed the oil after the high rpm run today.

This has the early pneumatic CAV Diesel injection pump (Tractor Serial number 1420) 1960.

Any ideas? I'd hate to blow up the motor from over-revving it, cuz I have lots of work for this old gal to do around here.

Bart D. Hull
Laveen, AZ

Anonymous-0 · May 22, 2014

Any Natural gas around? Any gas wells being drilled close by?

LMack · May 22, 2014

A little Gasoline in the Diesel will cause this kind of action. If it does take off and nothing will slow it down get clear (run to the rear) so you do not get hit by flying engine parts. You might want to drain the tank and replace it with good clean fuel.

Bart Hull · May 22, 2014

No gas around this way in Arizona.

Wondering if this is a problem with the early CAV pneumatic governors.

Bart

Larry B. 1486 · May 22, 2014

Air governor stuck. Make sure all linkage is free and the governor is freed up. Its been a long, long time but I think there was a oil line to the air governor.

JimB2 · May 22, 2014

Hi Bart, fuel rack could be sticking in injection pump. Try some Diesel fuel conditioner or a couple tablespoons of 2 cycle engine oil in the fuel.
You can stall it by putting it in 3rd or 4th high and braking hard.

Bob · May 22, 2014

Likely, the governor diaphragm in the IP has failed.

Rex in Australia · May 26, 2014

was it blowing lots of smoke at same time? Governor diaphragm. Easy to replace, just make sure the new one is oiled if leather, and CLEAN!
Rx

Bart Hull · Sep 26, 2014

(quoted from post at 09:53:54 05/26/14) was it blowing lots of smoke at same time? Governor diaphragm. Easy to replace, just make sure the new one is oiled if leather, and CLEAN!
Rx

Exhaust is under tractor so I didn't see if it was blowing black smoke. That said I didn't see it rolling out around the tractor like the blue smoke when it starts. I was also a bit nervous at the rpm's it was spinning at the time. Pulling the fuel cutoff didn't shut it down either.

Where can I get a online manual on the CAV pump? I would think that the diaphragm may be stiff and not returning as it should.

I need to find a tach drive for this injection pump as well. My B275 doesn't have the tach drive on top of the oil pump shaft.

Bart Hull
Laveen, AZ

Scary Ride today on the B275

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