Stalling at Idle w/ No Load

[HedgehogOutdoors]

Well, for the last few weeks, my alternator has been whining like a supercharger. I have no idea why, I am not running anything electrical that is different than it has been since I got the 4runner. When I use remote start, generally the first try the 4runner will not start. It will shut down and automatically restart fuel pump etc., and fire up the second crank. It will run for about 20 seconds, and die. It fires up again and dies a total of 4 more times before it gives up. It's been doing that the last 2 days, I don't know what the hell that's all about. It happens with everything on, and with everything off, doesn't matter.

During a huge snowstorm a few weeks back, we had a call for a car vs. pole, so I hopped in the fire truck, only to see my 4runner's running lights going, which I know I had shut off, which meant it was running without the keys, and without me hitting the remote start. I came back after about 15 minutes, running lights were off, as was the engine. Voltage appears fine according to the gauge, but why the hell is it stalling if it doesn't have to send power to anything other than the engine?

 

[fourwd1]

When an alt starts to whine (ie, a high pitched noise that varies w/engine rpms), it usually means a problem, typically one of the diodes in the diode-trio.

A large load on the alt (like all the lights and the heater blower all on) will make it worse.

There are several failure modes for the diodes. Bad diodes also prevent the alt from full output, or create a load that drains the battery when the engine is off.

 

[HedgehogOutdoors]

Bad diodes also prevent the alt from full output, or create a load that drains the battery when the engine is off.

So what are my options? Anything other than buying a new alternator?

 

[stevec5000]

Problem could also be due to bad bearings. Those can be replaced cheaply if they are a standard size you can buy off the shelf. Either way you won't know what the problem is until you take if off and examine it.

 

[HedgehogOutdoors]

Well, it turns out my alternator was bad like I suspected. On the way home from the ambulance corps for my EMR course a few Wednesdays ago, I got about a mile down the road, 4runner quit. Had my buddy jump me, made it halfway up my driveway and stalled again. The next day I drove it to the shop, stalled right as I pulled in, that's how bad it was. They put in a new alternator, a day or two later I smelled something burning, next day battery light was back on. The brand new alternator had burned up. On my third now, this one is working fine so far, and haven't stalled it.