alternator testers?

My alternator has started to sound like a supercharger... it seems to still be working, but I can't stand the noise. What kind of testing can be done to determine what needs replacing? Or should I just bite the bullet and get a new alternator?

Hold a long screwdriver against parts of the alternator when it's running (carefully). You may be able to feel the bearing thru your hand. Or holf the handle to your ear and listen. If the bearings sound or feel bad, they are.

Or get a piece of tubing to act as a stethoscope and do the same thing.

A simple check to see if it's charging is to put a screwdriver against the rear bearing. It it is magnetized, it's charging. You gotta be able to get right against the bearing, though.

what about the noise? has anyone experienced something like this?

Water pump bearings can also make a similar deceiving noise.

water pump was replaced 3 weeks ago

I think noisy alternator bearings is a common problem with that era Toyota, if the Wheeler Dealers episode on the OG MR2 is to be believed and your Celica and MR2 share that alternator. They just replaced it with a remanufactured unit. I would rather have it rebuilt by a local shop, since FLAPS alternators have a high failure rate. You can have it tested at a FLAPS if they do free alternator testing, but I would make sure the guy behind the counter knows how to run the testing machine first!

You could possibly rebuild it yourself if you can source the bearings and find how to rebuild it in an FSM or Hayne's manual.

+1 on local rebuild. I've had parts test "good" that were still shot so take any testing with a grain of salt.

I wonder if you pull the alternator belt and spin the sucker and see what it does. Maybe you can feel if the bearing is still alright.

bad bearings, take the belt off, turn the alternator by hand, should 'crunch' a little, voila, replace. Cadillac did that on one, worked fine but sounded like mice in a blender...

With my RX-7, I had a hunch the alternator was bad when one night driving home from the strip, the lights got dimmer and dimmer and then the engine quit and there I sat at the side of the road!

Noise usually is caused by a bad bearing. Easy to check as others have said.

Without knowing what make and model your car is, it's entirely possible you can buy new bearings and install them yourself. Most alternators are easy to take apart and put back together. Check rockauto.com for price and availability, for that matter Autozone also sells that sort of thing and you may be able to get them locally.

stuart in mn wrote: Without knowing what make and model your car is, it's entirely possible you can buy new bearings and install them yourself. Most alternators are easy to take apart and put back together. Check rockauto.com for price and availability, for that matter Autozone also sells that sort of thing and you may be able to get them locally.

Yes! I recently rebuilt the alt on my '66 Chevy II after ordering the parts from http://alternatorkit.com/

If you've got an old GM Delco/Remy, you've got it made. Now if I could just find parts for my 88 RX-7 alt. I think it's made by Mitsubishi....

In reply to 1988RedT2:

Unless you want to keep the car all original, I would suggest upgrading the alternator. There are plenty of alternators that will fit on an RX-7 with little modification, like the 80amp S5, 100amp FD, 95amp Ford Tempo/Mercury Topaz, or 130amp Taurus. You will need an aftermarket pulley (except for the S5 alternator) and the connector. I have a spare S5 alternator I can part with, but you will need to get a hold of the connector yourself. PM me if interested.

Unless you've installed a megawatt stereo, or have added electric cooling fans or other high amp loads, there usually isn't any good reason to put in a more powerful alternator.

stuart in mn wrote: Unless you've installed a megawatt stereo, or have added electric cooling fans or other high amp loads, there usually isn't any good reason to put in a more powerful alternator.

Yeah, I don't even have a radio in the car. The FC alt is known to be weak, but I don't really want to fiddle with making something else fit. I've had the car for years and only replaced it once, with the one off a parts car I had at the time. I'd like to rebuild the old one before the replacement goes bad.

Just thought I'd make the offer. I do have a 100amp FD alternator waiting to be installed in my turbo FC because I am going with a Taurus e-fan setup, which are know to be very powerful, but also to be amp-hogs.

Sure there is, I wasn't really stressing out my stock alternator, but it ran 12.8-13.1v and changed a lot.

I put in a mini van alt and went to a solid 14.2v, no matter what the load. My lights were brighter, windows faster, wipers faster, every thing worked better. So Id say it was worth it.

~Alex

just received some good news, my mechanic is giving me a free used alternator.

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