kevinr1247

Okay, so as I sort this '87 out and really drive it, there has emerged a possible issue. This issue is this.....at idle, whether hot or cold, the alternator light blinks in unison with a minor pulse of the engine idle. If I give it a little gas and hold the RPM at say 1000, the blinking goes away. Also and perhaps (un)related, I noticed that the brightness of the display on my original radio pulses slightly as well. But this doesn't seem to be contingent on the RPM of the engine, like the alternator light. In other words it doesn't go away when I rev the engine. Also there is a 'whine' that I never noticed, again, that sort of pulses with the idle.

I reckon this could somehow be related to two things that have recently been done to the car. The first, I installed a performance chip without making any idle adjustments. The second, the fan belt was tightened as part of the process for diagnosing another problem. Perhaps over tightened?

Thoughts and/or concerns?

Thanks again as always. Kevin

dshepp806

Belt needs to be "right", for sure.

Aside, it's time to break out the DVM and get some voltage measurements. Possibly (probably) the regulator, but would certainly check alternator and battery,...the "charge" state and battery load capabilities.

BEST!

Doyle

rusnak

You want about a quarter inch, maybe a hair less, of deflection when pressed in the middle of the belt. If you overtighten, then you can rub the fan against the fan shroud, or worse, crack the shroud.

The magnesium fan shrouds are NLA, and if you can find one you'll pay through the nose, so don't overtighten the fan belt. That also shortens the alternator bearing life.

You should check the charging state with a voltmeter. You should see over 13 volts, but less than 14.

It's a very normal part of owning a 3.2 to REGULARLY clean the battery clamps, and the DME grounds with a brass brush. SOP is to brush them until shiny, then make sure they're tight. Eventually on Carreras the positive battery clamp must be changed. I'd get one that solders in, or a premium one from a stereo shop, not the cheapo from the auto parts store. Eventually the negative strap needs to be replaced, and when that time comes, get a longer heavier one.

Lorenfb

"the alternator light blinks"

This is not a function of whether the alt belt was properly tensioned
or not. Most likely there is a problem with the alt, e.g. the slip rings
or the regulator brushes. Furthermore, not all 911 3.2 battery cables
need eventual replacement as mentioned as long as the cables are properly
maintained, e.g. not stressed when connected with a monster battery.

kevinr1247

Cool, thanks for the info. I'll start digging a little to see if I can sort it out. Let you know what I find.

Kevin

kevinr1247

Replaced the alternator. Everything fine now. The flashing light and "whine" is gone. 'Twas quite an easy job. It was actually more difficult getting it out than it was putting everything back together.

Thought about painting the housing and the fan but naaaaah. Just polished and cleaned it up some, and took advantage of greater access to detail the engine a bit.

Now onto getting the fuel tank removed and cleaned out.