Another alternator question.

[keith haw]

Ok, on my 87 4.0L the volts read almost down into the red at idle with the a/c or lights on. When the rpm's come up it gets up to almost 14V, most of the time. I've done the alt wiring upgrades and am running 0/1 welding cable from the battery. is it time for a new alternator or is there something I'm missing?

Thanks
Keith

 

[Urban Redneck]

Could have a dead cell in your battery. Have seen batteries with one dead cell still run lights and everything but not start a vehicle.

 

[5-90]

Before you suspect the battery, I strongly suggest you back-check your panel gage with a good multimeter, and read straight from the battery. My wife's 89 reads about 10V at the dashboard, but the last time I checked it (last week) I was still getting 15V at the battery and alternator. It's probably a connexion I need to clean and haven't had the time to do so just yet...

The voltage feed for the panel VM is pretty shonky - I don't take that particular gage as 100% reliable. Most of the others have been pretty solid - I check those signals as part of a quarterly inspection (when I rotate the tyres, check the brake linings, relube EVERYTHING, ...)

5-90

 

[keith haw]

Thanks for the replies.. It is an old battery. Maybe a good reason to buy a Optima. Checking the voltage at the battery sounds good also. Guess you really can't trust old stock gauges.

Keith