dimming lights + rough idle

[sea_urchin]

Got a couple of problems going on with my 1984 Carrera. I could use some input on where to start my diagnosis.


1. My headlights dim occasionally while driving. They only stay dim for about a second or so, but it can get annoying at times. I checked my grounds, and they look to be clean, but I have to admit that I haven't had the chance to clean them all up. Has anyone had similar issues? Any suggestions?

2. I had my car sitting in the rain all day last month, and the idle was very rough when I started it ... barely ran for the first 5-10 minutes. I kinda had to keep moving just to keep it from dying. I've had the car sit in the rain before without issue, but this rough idle issue has happened twice recently. Any suggestions?

Thanks in advance for any help.

[jevvy]

hello and welcome to pelican.
As others will say the first port of call should always be a search as most issues on a 911 have been covered in detail many times on this board however to help you on your way....

1. Sounds like a dodgy alternator or voltage regulator that is causing your dimming lights - I have replaced alternators on both my 911's because of this and each time it sorted it out. Its a pretty easy DIY if you have a few tools, I bought re-conditionded Alt each time I did it. An easy way to check is to get a voltmeter and check what volts you are getting at your battery with the engine running at idle and at more then 2500krpm - from memory at idle you should see 12.5ish volts and above 2500 rpm you should be seeing at least 13.5V and nothing above 14V

2. My 3.2 also used to play up when left in the rain too long - if you look at where your distributor and plug leads are you will see why...if they are less than 100% waterproof you will get some water ingress and make it run ruff until it clears the mosisture. Replacing with new parts will reduce this problem, parking under cover will most likley prevent it fully.

Good luck with sorting your first few problems

[sea_urchin]

Thanks for the quick response.

Bummer, I guess I gotta spend my next free weekend on the alternator. I was hoping to spend it throwing in my short shift kit

[jevvy]

you could probably do both - alternator will only take a couple of hours.

You might also want to check if your car has a seperate votage regulator as that might be a cheaper easier fix - I think 87 onwards the regulator is on the back of the alternator but earler cars have it in another location I seem to remember reading at some point.

Make sure you remember the orientation of the cowling on the back of the alternator as you take it out - you will need a pair of small hands and small spanners!

[scottb]

I had a similar problem in my 84 -- right before the alternator went south. I had mine rebuilt by a local foreign alternator shop. $89, IIRC.

Good luck.

[sea_urchin]

Thanks for all the help. Looks like the voltage regulator is on the back of the alternator, so I'll just have to get it rebuilt. I read through the my shop manual and it looks pretty manageable.