Charging Problem
 

I just purchased a 74 1.8L thats a great little car, but has one major flaw...the alternator won't put out a good charge.
What happens is when I start the car when cold, the alternator puts out over 13+ volts according too my gauge, but the voltage slowly drops down to just below 12 volts after approx. 20 minuts driving. This condition is even worse with the headlights on with a voltage of 12 at start, going down to 10 1/2 after 20 minuts. After a few days of driving the car with this problem, the starter is slow too turn, or may not turn at all.
I have replaced the voltage regulator and the alternator, and have checked and cleaned my ground connections with the same problem.
I'm now suspecting the battery, since I know the car sat for long periods before I bought it, although the battery is less then 2 years old and it seems too take a charge from my shop charger. I'm also suspecting my "rebuilt" alternator, simply because it was the least expensive {read cheapest} one I could find in my area, and it's rebuild quailty is questionable.
Any thoughts or suggestions on this problem would be much apprecitated, because I'm running out of options.

I had the same problem when I brought home my 74 1.8L. I solved it by replacing the battery, altenator, VR and cleaning every single ground I could find. Make sure the one on top of the engine case under the intake manifold is clean. It sounds like you did most of this but you might want to take the alt back to where you got it from and tell the to try again!!! Good luck but make sure you clean those grounds. Oh yeah, sometimes people forget to clean where the negative battery cable connects to the body as well as the mounting fixture for the alt...that is its only ground!!!

I had similiar problem with same car. check the belt. Since it will stretch as car warms up. Is your dash light also coming on at idle? Anyway, I cleaned everything, with some minor improvements. Finally replaced the battery with one of these new Optima gel-cell ones. the battery made a hell of a difference.

Hi Bob,

I had a similar situation happen to me recently. I just used one of the AL 75X Bosch alternators and replaced the regulator.

I now have no worries and I can run everything and know the battery is getting a sufficient charge.

Oh, and one more thing. The alternator had its own ground strap attached to the back of the alternator. Make sure you get one, sometimes the alternator loses it's ability to ground on the support bracket and it, over time, becomes less effective.

Good Luck,



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72'914
John@pelicanparts.com

Don't trust the alternator in the center console to measure the health of your charging system. It measures a circuit that is is affected by far too many other things.

To check your charging system, measure with a decent voltmeter directly across the battery terminals. Not the clamps, but the terminals.

I solved a similar problem on my car by removing the alternator and then the alternator bracket, and taking a wire brush to the back of the bracket and to the fan shroud where the bracket rests. The steel bracket and/or magnesium shroud eventually corrode, which give you a high-resistance connection. Especially when they warm up.

--DD

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Pelican Parts 914 Tech Support

A few pics of my car: http://www.pelicanparts.com/gallery/Dave_Darling