Hi George,

It turned out that the belt and the pulley were both shiny and although it didn't make any noise, it would slip enough under load to keep it from charging.

How true! When this happened to me, I went to extreme methods to prove it, first installing a temporary ammeter, to confirm what the voltmeter implied. Then I rigged a speaker under the dash to listen to the unrectified AC available at terminal W on Bosch alternators. I learned the glazed belt and shiny pulley combined in silence.

On the 240 and 740, the alternator is set in rubber, so the effectiveness of tightening the belt depends on bushing hardness. On the 240, the belts span three pulleys, so the benefit of having dual belts to offset the smaller pulley contact is compromised as the bushings are compressed, leaving the inner belt loose.

After replacing belts and bushings, roughening the pulley grooves and verifying the end of the problem, I removed the speaker and ammeter. Mama mouse later found the grommet where my temporary ammeter wires had passed through the firewall.


--
Art Benstein near Baltimore

My dog is worried about the economy because Alpo is up to $3.00 a can.
That's almost $21.00 in dog money.