Hi Only Volvo,

Thanks for thanking me. Sounds like a new thread is a bid for new input? If you're looking for a wider audience, selecting ALL/ALL does just the opposite; those reading the RWD forum for a specific model don't see any ALL/ALL threads.

However.

However, I wasn't contributing. It's a 940, right? I remember we worked together when you owned a 240, I think.

Reading the thread I can only guess at the trouble and point out some rookie mistakes we backyard mechanics very commonly make with electricity.

Here are two rules I believe would vastly improve the way occasional users of multimeters could get meaningful results.

Rule 1: Never attempt to measure resistance or continuity in a powered circuit.

Rule 2: Don't break a circuit to measure voltage. Measure voltage on an operating circuit with as little disturbance to the connections as you can manage.

I think #2 applies to your methods. When you disconnect something to measure voltage on it, the load is missing. The meter becomes the load, and modern multimeters are designed to present as little load as they can. Some mechanics will do this by load substitution -- by using a test lamp instead, but when they do, they are aware of how much current the test lamp uses and how it compares with the load expected in a circuit.

Question your assertions about "rigorously tested". I chased a problem in a junkyard-acquired rebuilt alternator I figured led to the car being in the junkyard. Called it my magpie moment. Saw a shiny alt nice and high up on a 7/9 car, easy to pull. Put it in a car I was preparing as a wedding present. It would charge for about 15 or 20 minutes and quit. When I took it apart to verify shorted stator wire turns when it got warm, I learned something about the reman industry.

The reason I mention this is your thoughts on overheating. When the stator wires shorted, the normal heat rise as it is developing current to replenish the battery after cranking was replaced by an abnormal heat rise. That's hard to tell in a 240, with the alt just below the exhaust manifold.

However.

As easy as it is to swap a 940's alternator, that's what you should do if you have one. And get a dashboard voltmeter like Marty suggested.







Pretty on the outside.



--
Art Benstein near Baltimore

I was married by a judge. I should have asked for a jury. - Groucho Marx