Alternator help needed

  • Thread starter Thread starter R Zych
  • Start date Start date
R

R Zych

Hi, today my 740 died on the highway. The radio was the first sign by
shutting off the heater fan started to behave erratically. I shut them both
off along with the headlights, then about 20 mins later the engine lost
power and I was able to get off the highway and it stalled on the offramp.
While waiting for the tow truck (30 mins) I was able to start the car but I
shut it off because the truck was coming. Once I was towed home ( 40 kms) I
started it again to drive the car into the garage and soon as I got it in
there it stalled again. All along there were no warning lights displayed.
I had replaced the battery one month ago so I know it was good. The
alternator was making a squealing noise which sounded like the bearings not
the belt.
The question is, am I safe to assume the alternator needs rebuilt/replaced
or could it be the voltage regulator?

1989 740 GL wagon

Thanks in advance, Rob
 
Hi, today my 740 died on the highway. The radio was the first sign by
shutting off the heater fan started to behave erratically. I shut them both
off along with the headlights, then about 20 mins later the engine lost
power and I was able to get off the highway and it stalled on the offramp.
While waiting for the tow truck (30 mins) I was able to start the car but I
shut it off because the truck was coming. Once I was towed home ( 40 kms) I
started it again to drive the car into the garage and soon as I got it in
there it stalled again. All along there were no warning lights displayed.
I had replaced the battery one month ago so I know it was good. The
alternator was making a squealing noise which sounded like the bearings not
the belt.
The question is, am I safe to assume the alternator needs rebuilt/replaced
or could it be the voltage regulator?

1989 740 GL wagon

Thanks in advance, Rob
Click to expand...
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 said:
Hi, today my 740 died on the highway. The radio was the first sign by
shutting off the heater fan started to behave erratically. I shut them both
off along with the headlights, then about 20 mins later the engine lost
power and I was able to get off the highway and it stalled on the offramp.
While waiting for the tow truck (30 mins) I was able to start the car but I
shut it off because the truck was coming. Once I was towed home ( 40 kms) I
started it again to drive the car into the garage and soon as I got it in
there it stalled again. All along there were no warning lights displayed.
I had replaced the battery one month ago so I know it was good. The
alternator was making a squealing noise which sounded like the bearings not
the belt.
The question is, am I safe to assume the alternator needs rebuilt/replaced
or could it be the voltage regulator?

1989 740 GL wagon

Thanks in advance, Rob
Click to expand...

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.
 
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