Advice required - generator warning

[matt643]

Hello all,

Looking for some advice.

I recently suffered an unexpected battery failure on my 986 whilst driving from my home in Bedford to North Wales.

The car was sluggish to start in the morning and I should explain is used on a regular basis, so the battery had no chance to flatten since its run the previous day. I stopped at a filling station on the A55 and had another sluggish start. Made it to my destination but on the way back home (same day) I stopped in the Chester area and was rewarded by the infamous clicking solenoid which I remember so fondy from my youth!

Anyway, a bump start later and I was on my way, all 200 miles of it, the car was OK so long as you kept the revs above 2K which was slightly traumatic through the tolls and at the M1 junction 16 closure but I still made it home.

Once in the garage at home I popped the bonnet (after opening a cold 'reward' beer!!) and checked the battery, 10 volts with the engine running rising slightly when the throttle was blipped, turned of the car and the voltage dropped to 8 volts so that was it, dead battery.

Swapped out the battery (60 quid from Euro parts or 160 from Porsche... same Bosch battery so guess which one went in) and then started the car and checked the voltages.

Brilliant! 14 volts max and settling to a nice 12.4 volts with the engine off. Test drive, all OK.

Until today.. Started this morning, no problem, no warning lights. Went to an appointment, got in the car, drove off, warning! battery/generator in the matrix display on the dash and a suitable red battery light. Blipped the throttle, warning went off. 10 seconds later, you have guessed it, warning! battery/generator failure. B*gger.

Luckily this time I was only a couple of miles from home so made it back but with the error occuring when low revs were in play. Popped the bonnet and checked the voltages, all OK. Charging OK and battery OK.

Odd. Left the car on charge for a bit as the battery was still only a couple of days old and then re-started the beastie, now the light came on straight away and the engine hunts for its idle point.

So what do we think? Failing alternator? Failing charge regulator or something else?

Your knowledge is appreciated.

 

[Glyn]

Alternator.

The regulator is built in to the alternator

 

[colinbythesea]

Its a long shot but if you have the ability to remove the alternator see if you can then remove the voltage regulator. Then look for a part number and manufacturer on the regulator and go to a good motor factors. Never had my Boxster apart but this trick worked well on my last 944. It was a Bosch regulator and the motor factor could order it direct. It cost about £14 and screwed into the alternator with 2 bolts.

 

[adrian996]

Hi Matt. ...Probably the quickest way to answer the question...

http://www.porscheclubgbforum.com/tm.asp?m=387844&mpage=1&key=&#387844

Unbelievable - but true.

Adrian.

 

[Black80XSA]

Definitely sounds like the alternator - with the engine running on a fully charged battery you should see 13.4-13.8V on a voltmeter placed across the battery terminals. Leave engine running and put all electrical consumers on full (air con, main beam headlights , fogs, heated rear window, air con etc) and monitor voltage - you should see it falling over a 3-4 minute period, turn some of the electricals off and see if its then steady or still falling.

 

[matt643]

Hello all, thanks for comments and thanks to Adrian for the forum link.

Looks like its time to remove the alternator and check it out.

Hopefully its the regulator and not the mechanical parts of the alternator as I do not fancy forking out £££ just after paying my insurance for the year! Could be an expensive month!

Apparantly the regultor is quite a common part and I even found one on Ebay.

Usefull link here if anybody else is having this issue:-

http://mike.focke.googlepages.com/replacingyouralternator

 

[matt643]

What a job that was! Removing the alternator took about three hours but replacing the regulator (separate part, £30) took about 5 minutes.

I can also see why the regulator failed, the cooling fins are pressed up against some plastic flexi conduit allowing zero airflow and hence eventually causing an overheat. Especially in the tight engine bay. Silicon hates being overheated.

You can see the crushed conduit in the attached picture.

The charge warning lights are now off after a long a bitter struggle to get the alternator back in and I see a healthy 14V across the battery, even with all of the energy guzzling extras on.

My only concern is that the idle may not be correctly set up as a couple of times yesterday the engine 'hunted' on idle. I read somewhere that after re-connecting the battery you should turn on the ignition and wait for 60 seconds before starting the car to allow the throttle actuator to home. This is a 2003 car with e-gas, does anybody know if this is the correct procedure?

By the way, and you probably all know this already! But to avoid the alarm going off when changing the battery turn the ignition ON and the remove the batterys ground terminal connection.

 

[JCB..]

Nice work Matthew.

My car occasionally hunts on tick over - it's done it for the last 5 or 6 years.

A dirty MAF is often quoted as being one cause - I bought the 'security' torx driver and contact cleaner but I've never been able to muster enough enthusiasm to get on and do it. [&:]

 

[Paul Fraser]

If you have an idle hunting problem I'd clean the ICV and the throttle body as well as the MAS. There are a few threads about this on Renntech.

 

[matt643]

Well the hunting problem has cured itself, I suspect that this was the ECU re-learning the engine characteristics, however after two days of perfect behavior... BONG! PSM failure, drive to workshop, BONG, ABS failure, BONG, airbag failure.

Luckily only a very short distance from my house, so popped back, opened the bonnet, battery voltage 8 volts. No generator warning light though.

Ignition off, that was it, dead. clicking solenoid, jumpstarted it from my spare good battery and checked the engine fired up. Checked the voltage, 13-14volts. Put on all loads, checked the voltage, stable. Turned off. Waited for a while, went to start, perfect.

This is odd, the alternator is charging OK, there is no warning light but suddenly and without warning stops feeding the battery and the first indication is that systems are failing.

So forum, what do you suggest? Maybe the clutch on the alternator is failing or there is some other alternator related issue. I am going to rig up a voltmeter to the car that I can see in the cabin just to check what is going on. However it 'feels' like a loose lead post the alternator. after my weekend BBQ its time to do some serious wiring checks.

 

[spyderman]

Not something as simple as a loose connection somewhere, is it? I had an electrical problem on a Vauxhall a few years back that was just down to a loose battery connection - even though it actually felt tight.

 

[adrian996]

ORIGINAL: adrian996

Hi Matt. ...Probably the quickest way to answer the question...

http://www.porscheclubgbforum.com/tm.asp?m=387844&mpage=1&key=񞬄

Unbelievable - but true.


(in reply to matt643)

Hi Matt. I hate to say it again but...


Did you get the alternator checked when you had it off ([]) the car?

Adrian.

 

[matt643]

Yep, had it checked by the local Bosch specialist. They ran it up on a test bench but I am mindfull of your experience!!!

 

[matt643]

That seems the most likely cause to me, there is a distribution box from the battery that supplies major loads and I suspect that this will be next place to check.

Cheers!

 

[matt643]

Right, all fixed. After ploughing through the electrical diagrams and testing the relevant areas, not many in this case, I stripped out the alternator again and tested it on my workbench.

As expected there was very little output so back to the electrical factors for a moan about the replacement regulator. This time they put the alternator with a brand new regulator on a Bosch test bench and left it running under load for 10 minutes, no failure of the mechanical parts, phew!

Re-fitted to the car and then turned the ignition key.... fired up straight away, no hunting at idle textbook 14.4 Volts across the battery and warning light out. Took it for a test run and all OK.

By the way and apart from the lack of voltage if the alternator is not charging properly you can see and hear the freewheel pully on the front of the alternator 'whizzing' after you rev the engine, this is because the alternator is not under any load.

So there we go, a faulty repacement regulator was the cause of my woes.

On the positive front replacing the alternator the second time around was a breeze, 15 mins to take it out and the same to put it back in. No seat removal or engine cover removal needed.

Back to Porsche open top motoring with avengence Whoo Hooo!

Oh, its raining... boo.

 

[Mark_Bennett]

Matt,

That is really useful information.

You don't fancy writing this up for the magazine do you? (Mostly the posts above would do!)

If you took any photos that would be great!

 

[matt643]

Hello Mark,

Yes, no problem. I would be happy to share the experience with the printed audience. Took quite a few photo's during the process and also can provide information on the electrical tests performed/where the wires go and what they do.

Matt

 

[Mark_Bennett]

Brilliant!

The magazine is always looking for technical articles. You can either send to me, or direct to Stephen Mummery (details in Porsche Post)

I'm so glad you took photos... []