Suspect Alternator Problem

[GreenMeanie]

Hello Everyone,

What a great forum, I think my question has been answered already but I would be grateful for a second opinion.

I have a 2002 TDI Elegance with 130K on the clock. Driving home from work today I saw the battery charge light flicker a few times then what felt like an engine hesitation coming off a roundabout. I also heard a noise which sounded like something dropping onto the undertray. The battery warning light did not come back on but strangely the steering felt a bit lighter.

My immediate thought was Aux drivebelt, so I pulled over (in the dark) and found the drivebelt was still attached and it appeared to still be tensioned. I had a quick look under the bonnet in a well lit forecourt and could not see anything untoward around the aux belt or inside the battery box. The engine re-started fine with no strange warning lights.

The Mrs thinks i'm seeing things, but one thing that has defintely changed is that having left the car to cool for a while, if you then re-start the engine, put the headlights on and slowly rev the engine in neutral, when you get to approx 2500rpm you hear a click from somewhere behind the instrument cluster and the headlights get a touch brighter.

From reading this forum I understand this could be a few things as below - unfortunately I don't have any equipment around me this instant to investigate further. Will try and get a multi-meter tomorrow. So:

- Alternator has gone - Will check for 14V with multimeter and under load

- Seized Alternator pulley

- Broken tensioner mechanism

- Corroded alternator battery wire

- Melted fuse box on the battery

- Some other electrical gremlin

What do you think the most likely fault is, as i'm currently trying to work out whether I can drive the car to work in the morning!? Is an alternator change something that can be done with a socket set and spanners, but no access to a ramp or jack?

Failing that, can anyone recommend a good garage near Aylesbury?

Will update with a diagnosis.

Thanks in Advance

Phil

[Dox]

Look at the pulley on the alternator, its a 2 piece affair and has a slipping clutch. A friend of ours was recently recovered with the outer part of the pulley fallen onto the undertray, the belt was still sitting on the alternator and all appeared well on first inspection.

[trundlenut]

When the engine is cold you will hear a click at 2,500rpm, it's the glowplugs coming on to help the engine run smooth, or at least assist ignition in the cylinders.

The alternator comes out from the top, the air con pump support bracket means it won't come out the bottom. But you will need to lock off the tensioner to remove the aux belt and you can't really do that from above. Really you need to remove the undertray, drivers side wheel and wheel arch liner to get the access.

I found that with a failing alternator pulley I got a sort of chatter when I let the revs drop suddenly, this was the tensioner bouncing around. You could also see the tensioner moving around at idle. If the pulley has seized you may have heard the plastic cap on the end of the pulley coming off, but it's only a bit of plastic and shouldn't make much noise. ON the 130 PD engine with a completely seized pulley the tensioner actually vibrates significantly and gets worse when the power steering is under load.

[mbames]

On mine, the half of the pulley sheered off once it has seized up. The PAS worked some of the time (I guess the belt was part-slipping, part not. Before this happened I had noticed the tensioner was rattling a bit more than normal, and on the morning of the failure there was an evil sounding grown from the engine (I wondered if all the oil had drained out of the car overnight!)

I had a similar noise of something falling off - it was the pulley which ended up on the under-engine tray. Mine failed in Salisbury one morning, so I drove to work (with no PAS), and had it recovered home in the evening (figured I might as well work for the day!)

My alternator ended up looking like this:

With the alternator off the car:

and new one put on:

Full picture set

[GreenMeanie]

Update:

Drove the car to work this morning - no issues

This evening, I've taken the undertray off and boost hose to get a bit of a look. Difficult with the access available to see anything, however I managed to get my hand on the alternator pulley and it felt like the last picture looks in the previous post. The pulley is there, its round with grooves on, flat top and there don't appear to be any cracks. Wiring appears to be intact

Couldn't get near the tensioner pulley so no idea what thats like but the damper is connected to something reasonably solid. So, I think the pulley and Aux belt are ok, although it does sound quite noisy at idle.

The battery is showing 12.8V with the engine at idle, turn all the lights, AC, Radio etc on and it drops to 12.2V at idle. Rev the engine upto 3000RPM and you see about 13.6V, so it would seem the alternator is doing something?

How do those numbers sound? My feeling is the alternator itself is on its way out.

Diagnosis ongoing

Cheers everyone

[trundlenut]

Is the tensioner still or is it moving/vibrating at all? Any movement and I would suggest the pulley is on the way out and the tensioner is probably knackered.

[GreenMeanie]

I couldn't really get to the tensioner pulley, I could move the rod of the stabilus damper. At idle the aux belt does make a bit of a noise, steam engine noise is the best description i could give

[mbames]

My tensioner started to make a bit of a "ticky" noise, and did so for about a year, but then towards the end there was a bit more of a "groan" noise, which I think was the pulley on its last legs.

To be fair, the pulley is a pretty common problem, but sometimes ignored or missed as on some instances the tensioner breaks first, so people replace that, and then a few weeks later the tensioner breaks again. When mine broke at the start of the year, several other Brisky members has similar issues all within a few days.

In my mind if you are going to replace one part, then you might as well go the full hog and do them both. Getting the alternator out isn't super easy, but it is better to schedule a bit of down time than suddenly end up with a broken car in the middle of a cold/dark/wet winter night.

[trundlenut]

I couldn't really get to the tensioner pulley, I could move the rod of the stabilus damper. At idle the aux belt does make a bit of a noise, steam engine noise is the best description i could give

Put your hanbd on the top of the damper on the tensioner you will be able to feel any vibration. On my car the damper went and vomited all of the oil onto the pulley on the tensioner and the aux belt.

[GreenMeanie]

Had a wiggle of the tensioner and it felt ok. Bit the bullet and took it down the dealer, still no repeat of the battery warning lamp. They found nothing except reporting the drive belt was worn, which they changed. Car is currently driving ok so will see how it goes. Having not seen the old belt I don't know what was wrong with it, but it had done near 130k so sounds plausible.

Thanks everyone for your help