Electrical worries

Guest · Jan 20, 2006

Help!

Have just returned from an aborted trip to see a friend which ended with me having to push my 911 up my drive out of the road with the aid of some passing kids!
My problem on the face of it seems electrical. it started fine but within about 5mins of driving with lights and fan on, it developed a bit of a stutter. i pulled over and the revs were kind of 'blipping' up and down. i turned off the lights and it seemed to settle. waited a few moments and then pulled away again. as soon as i put the lights on it went haywire again!
i mananged to limp back to my house (lights on half) where it idled ok for a couple of minutes, before stopping altogether. everything electrical was dead.
a few weeks back, the battery was flat, but i checked it for water (seemed ok) and recharged. everything was fine until now.

does this sound like a charging issue (alternator) or am i barking up the wrong tree?
i was planning on giving the only porsche specialist i know in my area (la rose, kent) a ring in the morning.....

Help!!!

Richard Savage · Jan 20, 2006

Lee

There are quite a number of possibilities obviously but, I had a very similar problem and tracked it down to a totally shot Rotor Arm! Check it out. I also replaced the distributor head / cap.

As to the lights / fan having an effect, this may / may not be significant. I would have expected the alternator to cope with the extra load OK. Is the drive belt correctly tensioned?

Your battery may be on the way out, correct electrolyte level or not! It's a question of illimination unfortunately.

R.

TopCarrera · Jan 21, 2006

Lee,

Your suspicion regarding the alternator seems well placed to me. If you recharge the battery and the car starts and runs OK this suggests a charging problem. It may not be the alternator but some other element of the charging circuit.

I experienced alternator failure about five years ago with my 84 car. I was surprised because the car had only done about 72 K miles at the time. I had exactly the same symptoms that you describe.

If it is simply a charging/alternator problem then any reasonably competent technician should be capable of diagnosing this and pointing towards exactly where the problem lies.

I was less fortunate than you and had to be "recovered". I asked the recovery vehicle driver to take the car to my nearest independant specialist (a few miles from home). Alternator failure was diagnosed and a replacement item (Bosch reconditioned/certified) was fitted. Whilst I was glad that the fix was simple I was surprised that a porsche should experience failure of this item at such mileage (possibly brushes/contactors etc breaking up with age?) and horrified at the bill for the work. Had I realised how much I was going to be charged I would have paid for an auto-electrician to confirm the problem, sourced a replacement alternator (there are several outlets offering exchange/recond units at fair prices) and done the work myself!

Hope you get back on the road soon - Good luck!

nathan 1981 930 G50 · Jan 22, 2006

Don't forget to check the earth strap that links the gearbox to the chassis.

Put a Volt Meter onto your battery while the car is running. You should get at least 13.8V. If you are only getting 12V then the battery isn't charging for some reason. If you get more than 14.4V then the alternator is overcharging and damaging the battery.

Try putting the lights, heater, heated window on while you are checking to make sure the alternator can cope with being loaded. You may need an assistant to rev up the engine.

Guest · Jan 24, 2006

Thanks for your replys

i have had the problem diagnosed as a faulty alternator by a distant relative who owns a garage. turns out hes worked on 911's in the past so i have entrusted him with getting it sorted. alternator going away for refurbishment. length of time off the road and damage to bank balance as yet unknown!

had a look on the pelican parts website where they describe removing the alternator. doesnt sound like brain surgery to me. i'd love to have a go myself but dont really have the confidence and/or time (my spanner experience limited to servicing my old mk2 golf gti).

i'm going to get clutch /throttle cables changed and maybe rocker cover gaskets sorted at the same time. can't help feeling i could do these jobs as well........