Irratic gauges = dying alternator?

[david85]

I sure you guys have had the cluster gauges start to read high for some reason then go back down every now and then. High temperature is usually the thing you notice first. Mine does it all the time, but usually only once or twice a day and a gentle tap on the dash resets it to reading normal (notice I didn't say accurate).

Earlier today I noticed a slight belt chirp but didn't think much of it, my bad. I didn't even pop the hood. After about 150 miles, the gauges were going weird everytime I slowed down enough for the engine to reach idle. Then there was a slightly sweet burning smell, time to pull over. One the side of the road with it idling the intermittent chirping changed to an outright squealing. I shut it off.

I pooped the hood hoping not to see smoke or worse but saw nothing. Looked at the AC compressor, that seemed fine and then tried to turn the alternator by grabbing the fan. Nearly burned myself and found it to be VERY stiff. Mystery solved. Thought about taking the belt off as I did have a tool kit with me, but figured the belt was probably toast by now anyway. Pulled out a knife and cut it off.

Drove home without break boost but made it just fine, not the first time I've had to get home with no vacuum. At least the tranny wasn't affected this time (C6=vacuum, E4OD=electronic). I wonder if the gauges acting up more often was a symptom of the problem because they read completely steady for the remaining 50 miles of the trip.

Pulled the alternator and found the front bearing shredded. Thought about trying to repair it, but I think I'll just replace the whole thing. Upon teardown, I found that some of the rotor had ground against the stator from so much play in the bearing. I'll price on out tomorrow.

I have to learn to listen to my truck a little better.

 

[Andylad13]

did you ever see a drop in voltage?

 

[MIDNIGHT RIDER]

YES, gauges going hay-wire is a sure sign of alternator failure.


My gauges used to do that "everything go to the highest setting" thing, about once a month; and, like yours, some light taps in a strategic location would settle everything back to normal.

I haven't done anything that I am aware of to cure the problem, but it hasn't done it in years.

 

[david85]

did you ever see a drop in voltage?

My truck has a amp meter instead of a volt meter (stock). It wasn't really affected much because it was day and I didn't need my lights on. It did read a little low after disabling the alternator, but if you are asking if it did anything strange before I pulled over, the answer is no. The only warning was a slight belt squeak earlier that day and the gauges going wonky every now and then.

It also occurs to me that if I had a serpentine belt instead of the V belts that all 6.9s have, I would have been stranded on the side of the road. Thats one thing this truck has been consistent with, if something goes wrong it can still get me home under its own power. It seems to have built in redundancy that was lost in later years as trucks got more complex.

 

[howards@howard]

crazy guages

If you gages are acting funny try replacing the I think its called the Instument voltage regulator it's on the back of the instument cluster. just plugs in. Your gauges run on less than 12 volts

 

[Andylad13]

the squeak was probably the bearings going on the alt.

 

[david85]

Pretty sure it was the belt. The sound was the same as the constant squeal that I heard when I finally pulled over except it was intermittent earlier that day.

I know about the regulator on the back of the cluster. Never bothered to replace it, but would you happen to know where it might be possible to get one?

 

[howards@howard]

Regulator

My gauges drove me crazy I thought the truck was over heating every time I filled the gas tanks. yes there connected.

In stock at NAPA