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Redland1

(03-25-2023 )DVT873 Wrote: Would be a good idea to replace the belt and the tensioner. Serpentine belts do wear and will slip. Most of the time they don't make noise. The tensioners get weak with age. If the belt is bouncing with engine running it is definately bad. IF it is slipping it can heat damage the bearing at the front of the alternator.
Fun fact. On ProStars slippage will heat up the coil on the air conditioning clutch. That changes the coil resistance which changes the amperage going to it. The body computer watches that closely and it has to be inside a narrow range. If the amps get outside the range the body computer shuts off the clutch. It will leave a code which reads something like "AC clutch over/under current". As soon as it cools down it will work again. For a while. Not knowing this or what the code means can make you lose your mind trying to figure out whats wrong.I've seen a lot of parts, including body computers thrown at that problem.
I do not know for a fact but suspect that most trucks with a body computer work in a similiar fashion.

A few days ago my radiator got a pin hole leak that happened to spray towards the fan and belt and that’s when the squealing originally started but had actually gone away by the time I was having issues with the voltage.I do know that I changed the belt on April 6 2021 when I purchased the truck.How often so they need changed and what is the tell tale sign that they are slipping? Also how do I know if the tensioner is bad?

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!