# Diesel Alternator Question



## Tomko (Jun 1, 2013)

Might be time to change your serpentine belt. Mine snapped at 95,900 miles.


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## ChevyGuy (Dec 13, 2014)

I'd suspect the belt first. A higher voltage means more power going into the battery, and a bigger load on the belt and more likely to slip.


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## MP81 (Jul 20, 2015)

Tomko said:


> Might be time to change your serpentine belt. Mine snapped at 95,900 miles.


And ours did the same around 127k miles...150 miles away from our house, halfway up the state to vacation. Did yours also appear visually fine like ours did?


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## Tomko (Jun 1, 2013)

There was no warning. It snapped on start-up in a Home Depot parking lot. Drove the car home. But dealer insisted on towing the car in the next day. They were concerned about seizing In the accessory drive system. But none was found.

Only time I’ve ever lost a belt in 42 years of driving.


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## MP81 (Jul 20, 2015)

OK - so similar to ours. I don't know _when_ it snapped, but we pulled off to swap drivers halfway up, and when I started the car and was backing out of the parking spot, that is when I got the "Service Charging System" message on the DIC. 

I suspect it let go right on startup, since that makes more sense of when it would have had the most stress, versus on a running engine (since I determined none of the pulleys were seized before I ordered the new belt for pickup 60 miles away for our friend to grab on her way up to drop it off, with some tools so I could install it - aka: really saving our ass). And since I drove it 15 miles after that happened (through a downpour, because of course, so plenty of accessories were on) there was clearly plenty of charge left to do so.

Belt looked completely and totally fine with an extremely clean break. I kept it for about a month after on the kitchen counter so people could look at it and also come to the same conclusion.


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## 15cruzediesel (Sep 30, 2019)

Easiest way is to get it squealing and use a squirt bottle of water and spritz the belt a few times. You'll know right away if it's the belt and the water is harmless.

Most likely the belt and it is squealing as the alternator load changes.


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## BDCCruze (Jul 12, 2017)

I did put a new accessory belt on at around 150k miles (at 205k now). But I didn't replace the tensioner, but I will when my next timing belt goes on.

I guess it's possible the tensioner is getting weak.


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## MP81 (Jul 20, 2015)

BDCCruze said:


> I did put a new accessory belt on at around 150k miles (at 205k now). But I didn't replace the tensioner, but I will when my next timing belt goes on.
> 
> I guess it's possible the tensioner is getting weak.


It's possible...but at 127k miles...that belt was an absolute _bitch _to put on.


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