Massey 255 not charging

bigjohn8229 · May 9, 2016

I am helping an older gentleman work on his 255 Massey Ferguson. The voltage at the battery is 12.5-12.6 volts and with the lights turned on drops to around 12.3-12.4 volts. I have had the alternator bench tested and the oil pressure switch tests at least 12 volts on both terminals when the tractor is running. I am not sure what to test next to pin point if there is an issue. Any help would be greatly appreciated!
Thanks,
John

bigjohn8229 · May 11, 2016

Anybody? There may not be a problem. I am just not familiar with this particular tractor to know. I have always thought that it should be generating atleast 13 volts.

MF#1 · May 11, 2016

We have a 255 that did something close but a rebuilt alt fixed it. I would suggest cleaning ALL the connections especially on the alt, checking the belt tension, and getting the rpms up past 1000 to check what happens then. That voltage does seem a little low. Does the battery run down over a few days or weeks?

bigjohn8229 · May 11, 2016

I had the alternator checked at one of the box stores and that is questionable at best. I plan to take it to a local man that specializes in old auto electric components to have him check it as well. A guy at work said that it could be the voltage regulator not allowing it to output the voltage that it needs. The tractor had been sitting for several years, but I trickle charged the battery and it has stayed up for about 2 weeks now cranking it every couple of days.
Thanks for the reply!
John

MF#1 · May 12, 2016

Okay, that sounds good but a diesel with a good battery can last a while without good charging. The voltage regulator is internal to the alternator so that might be the problem. There is a two wire connection on the rear of the alt. that needs to be taken loose and cleaned up, it's wired through the oil pressure switch that can be an issue. If the alt tests good then check the belt tension and make sure you have the rpms up when checking the voltage. You may want to check the amp meter when running to see if it moves any after cranking it up, it doesn't usually move very much. IF the alt. is okay then it may be a short in the wiring, never a good deal. Since it's been sitting for a time I assume that the battery ground and all other connections have been cleaned up, if not then it may not charge good. Hope you can find the problem, I hate electrical gremlins!

bigjohn8229 · Jun 10, 2016

Finally found the problem! The terminal in the weatherproof plug at the alternator for the exciter was broken. The "tang" on the inside of the terminal had cracked and was allowing it to not hold pressure on the male terminal and only make intermittent if no contact. Funny thing- I started tracing each wire and connector at the battery side working towards the alternator. Had I started at the alternator and worked towards the battery this would have been one of the first connectors checked. Just glad it is working now. THANKS for the help and replies!!

Massey 255 not charging

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