[GNvsTA]

I have been noticing two possible problems on my 77 GP, 400.

First, at night, when I have lights on, they start going dim when I am stopped at a stoplight,etc. I notice that the amp gauge will drop down too, and if I have a turn signal on, the needle will bounce back and forth. When I accelerate and driving, the gauge is up where it should be and lights are bright. The battery is newer and the alternator is newer. I replaced both at the same time, getting the stock alternator. I have had Advance Auto test it a couple times and never shows a problem. Any thoughts on what to look at?

Second, the temp gauge will not go up much past 100. I am guessing it is sitting at 130-140. I have never messed with the thermostat, so I am not sure what temp is in there. But I am guessing it should read higher anyway. Other than the starter acting up when the car is hot, car runs great.

[2002Z4CSS]

Put a volt meter on the battery at idle with the turnsignals on and see what it reads. Does the problem go away with a bit of RPM? Is the alt belt tight?

[GNvsTA]

Goes away with RPM increase. Belt appears to be tight, no squealing or anything. Gauge reads just above 13 with no lights or other load.

[2002Z4CSS]

Originally Posted by GNvsTA

Goes away with RPM increase. Belt appears to be tight, no squealing or anything. Gauge reads just above 13 with no lights or other load.

Almost like your alternator pulley is too big of diameter causing the alternator to turn too slow. Have you had the alternator tested?

[GNvsTA]

Tested alternator too where I bought it. Said no issues. Were there two options for the 77 GP as far as alternators go? Maybe I just need one that puts out more juice?

[1967Tempest]

I have the same issue. Volt meter jumps in idle with the turn signal on. I have a 100A alt and a new Optima Yellow top battery. Fully charged. Still does it. 2 things that will help are.

1. Add a second charge wire from back of alternator to battery. Use a fine stranded 4 or 6 GA wire. Usually at auto part store in the battery section.

2. Get another 4 or 6 GA black wire and ground the alternator. Over time the ground is not the best. This will help the alternator get the amps to the battery and have the ground to keep it cool.

I just learned both of these as I killed ANOTHER alternator. I think my issue is that at idle I am exceeding the output of the alt.

http://www.alternatorparts.com/do_i_...ttery_wire.htm

HTH,
Dave

[mike nixon]

Originally Posted by 2002Z4CSS

Almost like your alternator pulley is too big of diameter causing the alternator to turn too slow. Have you had the alternator tested?

DIng Ding Ding, have the Alt test on the car with a LOAD on it at idle.

Mike

[GpFreak]

Does it have a stat in it? Might be stuck open.

[1967Tempest]

Originally Posted by 2002Z4CSS

Almost like your alternator pulley is too big of diameter causing the alternator to turn too slow. Have you had the alternator tested?

Just got this one. Should be here soon. Might help both of us..

http://www.qualitypowerauto.com/catalog.php?item=67

Dave

[dedsleds]

check alt output running w/load....maybe the voltage reg in alt is weak.....do a load test on battery while you are at it.

[1967Tempest]

I just rebuilt my 100A 1 wire alt. Volt gauge in car was reading 13.5V. Hooked up mulitmeter to battery. Reading 14.7 just as it should be. So I might have a loose wire on the gauge or a ground issue.

might help you to put a multimeter on it and watch the voltage at batt with load.
.02$

Dave

[GNvsTA]

Thanks for the suggestions all. On vacation starting today, so I should have time to tackle it!