View Full Version : Question A4 2012 2.0 TDI Serpentine Belt Routing

29-08-2017, 12:21 PM
Hi there

I'm a newbie on here so my apologies if this info is somewhere within an existing thread, but any advice/pointers in the right direction would be gratefully received. I have an A4 2012 2.0TDI & the serpentine belt snapped yesterday due to a siezed air con compressor clutch. The air con hasn't worked for 2 months now & finally the belt gave up the ghost. A very nice repair man fitted a shorter replacement belt to get me home but that has also now snapped, so the car is now off the road.

Question is can I get hold of a shorter serpentine belt to bypass the air con compressor altogether & if so, what length would I need? I'm not fussed about the air con as I can happily live without it, however I might tackle that in due course.

Any advice would be welcomed.

Thank you
Ian (aka Windsor66)

29-08-2017, 01:29 PM
Have you got the old belt to measure its circumference or measure it with some string,failing that dismantle the clutch so its freewheeling,if you can measure it I can tell you if a 1.9 tdi will fit.

29-08-2017, 01:40 PM
you need to also find out why the shorter belt snapped as well. Something tells me it might be one of the idler pulleys which has seized, since the belt is off check the idlers turn freely without noise.

29-08-2017, 01:57 PM
Sorry I meant measure the shortened run.

29-08-2017, 06:10 PM
HI all

Thanks for your replies. I've checked the alternator pulley & the two idler pulleys & they are all running OK. One idler pulley is a little stiffer but still turns OK, though not as much as the other one which spins freely. It's only the A/C pulley that's totally seized.

If I've got the run of the belt mapped correctly, the total length is 102 cm. That's assuming I need to secure the belt round both idler pulleys & avoid the A/C unit altogether (as it's totally seized solid). Sorry for the poor graphic, best I could do in the time I have!


29-08-2017, 07:14 PM
The one I was going to suggest off a 1.9 with a separate a/c belt is 1435mm so thats out, might not be possible to get one,may be worth getting a second hand comp.

29-08-2017, 07:29 PM
Ah blast, no worries - thanks for the suggestions, most appreciated. The a/c pulley is seized solid but I've not been able to check if it's just the clutch that's gone or the entire unit. I'll have a look when I can & see if the clutch has welded shut before going down the route of a new compressor.

The car is immobile right now so anything that needs doing will have to be done on the driveway.

..and there's me thinking this was a dream car to own!

29-08-2017, 08:03 PM

29-08-2017, 08:53 PM
Last update for the day. I've now managed to get the compressor pulley to turn, and turn relatively freely after a fair bit of WD40 and some elbow grease (well, wrist grease to be precise). Will have another look tomorrow as I've given up for the day on account of the fact it's now dark & my hands are bleeding!

If the A/C pulley frees up & spins nicely, I should be able to fit the proper sized belt around all pulleys - fingers crossed (when they've stopped bleeding that is!)

Thanks for all your help, will keep you posted on how it all pans out

02-09-2017, 03:08 PM

Right, after purchasing a new serpentine belt (and a trolley jack & axle stands to remove the undertray so I could clean out the remains of the old belt!), I finally got the new one fitted. Streuth, that wasn't easy! Managed to get the belt round the crank & AC pulleys, then round the tensioner but couldn't get it over the alternator pulley. I managed to concoct a long spanner to pull the tensioner aside and then fitted the belt OK - took minutes once I'd worked out how to do it.

Trouble is now the engine management system cuts the car out almost immediately on starting, followed by the flashing EMS light & a warning tone. Now I have no idea what to do as I can't move the car to get it to a garage to be checked over.

Any ideas for some possible obvious things to check? I've disconnected the battery to try and reset the EMS, no luck there. Hoping it might be something simple but unlikely. Good news is that the new belt is at least turning so if I can get the car going, at least the battery will charge.


02-09-2017, 04:21 PM
Is it the car symbol with a key inside,or what? describe,does sound like your immobiliser kicking in.

02-09-2017, 07:40 PM
HI, thanks for replying.

It's not the car symbol, it's the amber glow plug light that flashes & then a constant warning tone sounds. The engine turns over, then cuts out immediately after 1 second so I'm assuming it's something serious or maybe a sensor has been sheered off when the previous belt disintegrated.

I think I need a VAGCOM specialist to come & plug into the car unless there's some obvious things to try.

Thank you for helping by the way, really appreciate it.

02-09-2017, 08:09 PM
Yes you'll need to get it scanned,otherwise its just guesswork.

21-09-2017, 12:45 PM
Good day all

The story so far! Have managed to find a local mechanic who is an absolute star. He came round, diagnosed & fixed the disabling of the engine & managed to get the car to move as far as his workshop, whereupon the replacement belt snapped again! It turns out the air con compressor is knackered so that needs replacing & the previous belt snap had knocked out the Cam Shaft sensor, so that needs replacing too. Not too bad on the whole so far, although he has found fragments of the previous two belts around the engine casing so I'm hoping it hasn't affected the cam shaft alignment & timing belt - fingers crossed.

Thankfully he can fix everything, which is more than the Audi specialists did when I took it to them (that's another story). Lesson learnt here - use your air con & get it serviced regularly, otherwise the compressor siezes up & the impact can be disastrous (as I've found out). Oh, I've also purchased Ross-Tech's HEX-V2 kit so will be plugging that in when the car comes back & getting used to reading the thing as much as I can.

Thanks to you all for your posts & help - it's very much appreciated.

Happy driving
Ian (aka Windsor)

27-11-2017, 02:34 PM
Afternoon all

Long time, no speak but still here & the ongoing saga with my delightful A4 continues. It's coming back from my mechanic today, having confirmed that the last aux belt break has in fact knackered the timing of the cambelt & as a result, the engine is totally knackered. I'm now stuck with a nice A4 that won't work & needs a new engine, however I'm really thinking of now getting rid of it. Need some further advice please:

1. Any ideas on where to get a new engine would be appreciated? I've been quoted various 4 figure sums so far & am thinking that it's probably best to just write the car off & get a smaller more economical one, now that I'm not doing the miles. however if anyone knows of somewhere I can get a decent replacement engine, I'd be only too happy to know.

2. Failing that, any ideas on where I can go to scrap the car? I've seen various websites offering great prices & car collection but I've no experience of them, so any advice would be welcomed.

Many thanks

27-11-2017, 09:16 PM
Sell it on ebay as spares and repair. You should get more than scrap.

Sent from my HTC 10 using Tapatalk

27-11-2017, 10:09 PM
I agree that selling on ebay is likely to yield the best price.
Sorry to hear of your misfortune. Thanks for sharing the experience which stands as a warning to us all.
You could of course offer in the marketplace section on this forum first.
Good luck.

28-11-2017, 11:53 PM
You might be lucky and it maybe just some bent valves,or worse bent conrod might be worth taking the head off to see,your problem is if you have to pay for the labour the cost stacks up so selling o on ebay for spares may be your best option.just a aside is the engine running at all?

29-11-2017, 11:47 AM
Thanks for the info, most helpful. Sadly the engine won't start at all now & as you say, it's paying for someone's time to do all this that would just stack up & there may be no chance of getting it fixed anyway. My mechanic has a mate who used to work for Audi so he's trying to see if we can source a replacement engine that we can fit, though it's likely it will need to go back to Audi for "reprogramming" into the car.

Just waiting to hear back now. I'm hoping we can get it running again so that I can at least either use it for a while or sell it for something cheaper to run, now that I'm not doing the miles any more.

Thanks again for all your help over the past few months, really appreciate it.