1978 Allis185 surging by 100 to 200 rpm's

[kbrad1956]

I have had this 185 for a year and have not worked with it a lot . I surges by 100 to 200 rpm's most of the time and when I take it up to 1500 or so it might jump by as much as 500 a couple of times and settle back into 100 to 200 surges . When under load it is not as bad but still unstable . It starts well in warm or cold weather . I have read that a bad or clogged return check ball at the injection pump could cause it but my pump does not have the check ball fitting . I also have read that not all 185's have the check ball fitting there and may be inside the pump . Bowl is clean and I have no fuel restriction out of the tank or to the new fuel filter . Any help with things to look for would be appreciated . And have great 4th .

 

[DrAllis]

Your injection pump return line fitting on the top cover of the pump DID HAVE a glass check ball and spring in it when built at the factory. If the fitting has been gutted (glass ball and spring removed) it is because it was plugging and someone removed it. That is a stop gap repair to keep the tractor useable until there is time to overhaul the injection pump, which is what it probably needs. All diesel engines with a RoosaMaster/Stanadyne injection pump has this check ball and spring regardless of what someone told you or you read. The final thing that happens when let go long enough is the governor fails and the engine speed over-revs.

 

[Dieseltech]

Sounds like it's time for injection pump repair. DON'T run it much longer or you WILL shear off the weight retainer pins, SIEZE the hydraulic head and BREAK the drive shaft. Have seen that happen too many times in fifty years and counting of injection pump service.

 

[m16ty]

Yep, your governor flex ring has failed.