Do I have an electrical problem?

[BIOBEV]

Hey Guys can you give me some advice? I have a 1988 6.2L 3/4 T Suburban. I recently changed out my batteries and replaced the belt, shortly after I notice my amp. guage nearly goes up to the red zone and fluctuates between the danger zone and just past the 13 mark on my gauge. Do I have an alternator problem, bad batteries(they are new). I am doing damage driving it. As you can tell I am no mechanic, but here in Arizona most garages look at diesels like they are from Mars. Any advice is appreciated.
Thanks

[john8662]

Mines been doing this for years, especially with a set of hot batteries.

I thought it might be a problem too, but has settled downs slightly.

J

[BIOBEV]

Well today it went into the red zone !!! It starts out just past the 13amp mark for a few minutes when I start then creeps up and back and shortly after goes up to the red and fluctuates. I am afraid to drive it as I do not want to cause damage, Should I drive it? Are one or both of the new batteries defective? Is my alternator going? Am I causing any damage? Please advise!
BIOBEV

[DmaxMaverick]

You need to confirm your voltage gage readings with a meter. If the meter concurs, then the VR in the alternator is failing. Driving it isn't too bad if you have to, but turn all the accessories you can to keep the voltage down. Headlights, blower, rear blower (if you have one), radio, dome lights, etc. If you drive it for a long period, or let it go too long, it will kill new batteries. Headlights and wipers will work extremely well for a while, though. Be wary of a "rotten egg smell", which means the batteries are getting cooked. A worst case scenario would be ruptured batteries, but happens rarely with single batteries, and more rarely with duals.

If you find the VR is the problem, I think the 1988 alternator still had the voltage regulator module, and can be replaced very easy for $12-$30, depending on the alternator model, and the good kits come with bearings and brushes. Napa, Autozone, Kragen, etc. only needs the amp rating to get you the correct module. Replacement requires removal of the alternator and splitting the case. If that's what you need to do, we can walk you through the process. It's easy to do, but takes a little time the first time. The module is the part the connector plugs into, and looks similar to this:

[N9Phil]

I would check the voltage at the battery with the engine running. Your alternator should be putting out between 13.6 and 15.0 volts. Gauges in the car can get flakey and give false readings. I just read 14.6 to 14.8 on one of my 95's. My Milton battery load tester says anything over 15 volts is high output. Any place that sells batteries should be able to put their load test meter on your battery and tell if you are OK


N9Phil

[BIOBEV]

Thankyou so much for your inputs, this site is a real help for me. Anyway! I just took it to a nearby Checkers and had it tested, it showed excessive charging on their meter, so it sounds like the voltage regulator from the advice you guys gave me. I am relly not comfortable tearing it apart and probably if I did I probably wouldn't be able to get it together right and have to buy an alternator anyway. So one last opinion! Who would you guys buy an alternator from and what brand would you buy. Checker carries Autolite but not convinced that is the best choice. I read from other post that certain alternators have pulley problems and throw belts, don't need that problem. If I am going to replace it I want to do it right.
Thanks
BIOBEVl

[DmaxMaverick]

Give the regulator a try. Seriously!

All you need to do it is some tools and a couple tooth picks or paper clips.

Once it's out, you just remove the 4 bolts that run the full length of the case, then pull the case apart. The regulator will be bolted to the bottom/inside of the rear case half (1/4" or 5/16", IIRC). Remove the screws, replace the VR and screws. Bearings just pull out/push in. The tooth picks or paper clips are for holding the brushes during assembly. There are 2 holes in the case bottom just for this. Hold the brushes in and insert the picks/clips through the holes from the outside. This will hold the brushes back while you assemble the case halves. Replace the case bolts and you're done. It's just too easy not to try. There's only 3 parts to deal with....2 case halves and one regulator. There's nothing to "screw up" that can't be cheaply replaced. If you get it apart and it looks like it's totally gone inside, well.......you were going to buy one anyway. I can do them in about 5 minutes, but anyone should be able to gitterdun in less than 30 the first time.