Mk2 2.0 D4 grinding/scraping noise

[Mike169]

Good morning Johan, below is a message sent to me by text from my friend.

Basically this is normal test procedure to test an alternator or to test if there are any electrical problems within the electrical circuit.

Assuming the problem is with the charging circuit, then you need to buy a multimeter capable of 10 amps. With the engine running check the Battery voltage which should read about 13.8 to 14 volts, give or take a bit. Then with the engine running disconnect the positive terminal, switch the meter to 10 Amp mode and put  the meter in line with it to the Battery and see what current it is putting into the Battery. At which point the red dash light on the dash should go out. If it's blowing fuses it's likely the diode pack in the alternator is knackered. Assuming they are using the same design as older models.

Have fun if you go down this route and if the alternator is faulty I am sure you can get yours repaired for much less then prices you have already mentioned.

Regards, Mike.

[xzirri]

Thank you Mike! Found a shop that sells multimeters for a 10er, will test it later today! Fingers crossed I get somewhere around 14 V at the Battery with the engine running 

[xzirri]

Bad news, got 11.8V at the Battery with the engine running  I’m guessing disconnecting the positive terminal would stop the engine. I would like to measure the output at the alternator as well but I can’t figure out how to remove the plastic cover for the terminal! I’m used to rubber covers, which are easy to remove, but this one is a PITA... Do you know how it can be removed?

[Mike169]

Hi Johan, alternators often have very small bolts or even screws to hold the cover on, a pain I know but remove the alternator to access the fixings if need be then refit it without the cover on and repeat the test.

If you are only getting 11.8 volts at the Battery with the engine running, is it the same without the engine running?

[xzirri]

Ok so here's an update.

I managed to get that cap off using some force. I measured the voltage at the alternator and it was dead. I have also talked with the only alternator repair shop in my area and they told me they'd charge me £ 60 to diagnose it, and then it'd be at least another £ 80 for parts, and that's without the cost of labour.

The local breaker didn't have the 100A alternator, only the 90A. Since I couldn't find any info on whether it would fit or not (and since I'm planning on upgrading my audio system this summer with some amps and aftermarket speakers) I ended up buying a rebuilt unit for £ 150 with 2 years warranty.

I guess I'll have the part by next week, can't wait to get it installed and get back on the road again! However, last time I tried to take off the serpentine belt I was only able to depress the tensioner a few millimeters. I suspect the wrench wasn't long enough. Will post back here when I have managed to replace it!

[Mike169]

Hi Johan, well done for working your way through the problem, I am guessing the diode pack has gone in the alternator unit. I am assusimg you have a Battery charger, may I suggest you charge up the Battery, it will take a full good 2 days to fully charge it. After this time and the Battery charger disconnected leave the battery to stand for a few hours and check the voltage with your multimeter to see how many volts are in the battery, you are looking for 12 volts plus. Mike.

[xzirri]

Ok so here comes a little update:

I checked the Battery after a charge and it holds the voltage. In other words, Battery is fine.

I decided to replace the alternator myself, and within two hours, the new one was in place. However, I did the rookie mistake of forgetting to disconnect the Battery! The alternator-to-battery wire terminal touched the manifold cover and the ALT 120 A fuse (main fuse, I guess?) was blown.

I had to take the bus to the dealership to buy a new one. As I was installing the new fuse, I managed to drop one of the bolts into the engine bay. Bye bye boltie 

Luckily I had another bolt of the same size laying around in my tool box. Everything is working perfectly fine now! Been quite the journey!