Dmax alternator time?

[JR]

So running my little RV cooler I noticed the running voltage was around 13.5, sometimes goes to .8 and sometimes a little lower than .5. This is on the CTS monitor and the dash shows about the same. This was after I unplugged the cooler to see if it was dragging in some.

Batteries are just a year old, new interstates from costco. Before startup I see 12.4 on the CTS, so think I am good. Think I will through a meter on it first though to be sure, but it 10 years old.

So I am thinking the Alt is on the way out. Now true it has been hot here (107 again today) and all runs fine but I know it should be about 14.5 volts when running.

Called Napa and got a rebuilt (3 yr warranty) and found the Dmax has a clutch on the hub? Look at yours, closed front it has a clutch, nut showing it does not. Never heard of this but it is GM.

[JR]

I did it and the belt. Running over 14 all the time now, both gauges. Belt was worse than the Alt, but 126K it did show some wear.

The right tool for the belt tensioner makes all the diff (HF) Also made a tool from 1/8 rod with a 90 on the end to push or pull the belt.

Now if I can get the #6 glowplug to work normal. Replaced (cheapo) and it does the same. Does each wire have a connection in the module, or is it just a big harness?

[Nate]

so when you replaced the main serp belt, did you have to take off the fan or did you just fit around it or?

[JR]

so when you replaced the main serp belt, did you have to take off the fan or did you just fit around it or?

It goes around the fan hub and crank, so no. Just a pain as there is no room. I took the upper shroud bolt out (allows much easier tension access) and the lower cover off. Then I cussed for a half hour. 

[EL TATE]

I feel your pain, literally. I did my belt in a campground in 20 deg weather with a cracked rib when my idler pulley took a dump on me. Not easy at all. I have noticed my alt puts out less than 14 volts for the first few seconds at start up, then cranks up to over 14 and the lights brighten up. not sure if this is the clutch you're talking about or not, but it's consistent with each startup.

[KensAuto]

The clutch just allows the alt. to "overrun" which keeps the belt from vibrating (think one way sprag). It's normal for the pcm to ramp up output on startup....it makes things last longer.

...some of the older 7.3s took up to 15 seconds for the alternator to engage....don't ask me how many I replaced before learning about that one.

[JR]

Yes. I read up on it after i asked.

Still at camp. Be back sat late

[JR]

I'm back and all went well. Glad I did it as we used the truck for charging the whole week. Idled a few times with no issues and it pulled 14v.