Alternator help needed

Need to also check all ground points and check your engine wiring harness for shorts - you may be surprised by what you find.

Sounds like the alternator to me. They have several components that can go: regulator, bearings, brushes, even the coils, and I think they have diodes also.

I have experience with 240's, not 740. On the 240 the regulator is built into the rear surface of the alternator, so to taking out the alternator lets the rebuild shop verify the voltage regulator also.

I had an alternator rebuilt and it lasted just over 5 years and about

125,000 miles or so before needing another rebuild. Nothing is forever.

The 240 alternators are mounted on two big rubber bushings, about 1 1/4" or 30 mm. diameter. I presume the 740s are similar. When the bushings wear the alternator slides on its mount, and the drive belts no longer line up evenly on the pulleys. Lots of squealing and belt wear, and one of my belts eventually broke from the stress. The bushings are only a couple dollars, but a bit of a pain to swap. Well worth the effort. Power steering pumps and maybe also A/C have similar mounts.

Bruce

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R Zych wrote:

From the noise your heard, it sounds like something mechanical within the charging system has failed. Since you have in the shop now, I imagine you'll find out soon enough what the problem is. However, if you were going to tackle this problem yourself, I would remove the alternator and bring it in to a neighborhood auto parts store. Many of them have a bench jig to test alternators and can give you a diagnosis in just a few minutes.