15.2 volts at idle too high?

[zak]

In figuring out why my battery died I noted 15.2 volts at the battery posts with engine idling - did not change when I put headlights on.

Time for a new alternator?

1995 MTX.

 

[luigisho]

Sounds like the regulator is failing. That voltage is a little too high especially under load.

 

[93markVIII]

yep. what he said.
15.2 is too high. bad regulator.

probably replaceable if you have the skills/tools.

 

[typhoon5000]

I'm with these guys, been there before. You can replace just the regulator, not the whole alternator, but taking the alt out to replace the reg makes it a much easier job IMO.

 

[hawkeye18]

Yup, regulator's gone.

I've replaced several, and as long as you have a 100w soldering iron you'll be good to go. It's not too hard. Just make sure you use a paper clip or needle or something to hold the new brushes down while you're assembling the two halves. There's a hole in the back of the alt for that purpose. You'll see what I'm talking about when you get there.

 

[zak]

Thanks Hawkeye. Based on storm-chasers write up here:

http://www.shoforum.com/showthread.php?t=96798&highlight=alternator

it seems like its the rectifier (diode trio) that needs a soldering iron (think I have a 30 watt). The regulator and brushes/brush holder are supposed to be bolt in on the 3G alternators (which include 94-95 MTX).

Perhaps soldering of the regulator is needed on the 89-93 2G type alternator?

 

[Ishodu]

Ya the 94-95 mtx reg and brush holder assembly is a few minute job once you have it out. And requires no soldering.

 

[hawkeye18]

I seem to recall needing to desolder two little arms that connected the regulator to the rectifier pack, but honestly it's been so long since I did that repair my memory might be fuzzy. This was on a 93-95 ATX alternator too, so yours might be different inside. If it's only bolts, then sweet! Less work for you.

 

[Ishodu]

Here is a pic of the voltage reg brush holder unit upside down. I had a issue with flickering lights and voltage drops. You can likely see why.
2 screws hold the bush holder in place as well as the 2 terminals from the regulator.

 

[zak]

Found a 1997 2.0L Countour alternator with 17 K miles on it, and put a new 1994-1995 SHO regulator in it.

14.45 volts loaded (heat, headlights, rear defroster, radio) or unloaded at idle.

The Countour "rear ear" insert was unthreaded. I thought of just putting a nut on the long bolt but not much thread engagement. I drove the bushing out using a 22 mm socket, 9 mm deep socket, and a vice under the socket, so that force was only on the one ear. Used the bolt itself, fully threaded, to pound the threaded sleeve into the Countour alternator - will add this to the 1994-1995 MTX alterantor sticky.

Thanks to all for your advice - zak