Help! Truck on side of road. Voltage steadily dropped to 7.5 volts and died

[DVT873]

Never found a hard and fast spec. If you see any bounce in the belts with the engine running that is a clue. Class where I first learned about this the instructor said 5 yrs for both. That was about 14 years ago. He was from Gates so he may have been a little biased!! There is a wear guide tool for the belt groove depth but I never found it useful.

Same overall lack of info for the tensioner. Anytime we do an alternator or AC clutch/compressor replacement we recommend replacing the belt and tensioner if there is no replacement history. There usually isn't. Give the idlers a spin while your in there. Once in a while a bearing will be rough.

Get an OEM belt if you can. A belt marked Cummins w a Cummins part # should be a better belt than one that says Gates even tho Gates may make both. The Cummins belt is built to Cummins spec which is their spec. Or Detroit, or CAT etc. You can kind of feel and see the difference between an OEM belt and say a NAPA belt. Not a huge deal but IMHO OEM is better. Have seen fleet data in the past that tends to verify that.

FWIW we have fixed AC compressor cut out problems with just belt and tensioner replacement.

So your belt is coming up on two years old which means it should be good for three more. But if you do replace the tensioner I would replace the belt again so I'm starting over with everything new. Throw the other belt in your roadbox that way you will never need it!