AUX belt question 2013 Leon FR mk3 TDI

[WillisBruce]

Hi Guys,

I recently had my cam belt and water pump changed by a trusted mechanic (or used to be trusted now, but more on that later) and he didn't do the AUX belt.

This I'm not fully blaming him for, as I should have known really, but surely you would at least ask if I wanted it changed?

Anyway, to cut a very long story short, my car is now hating life, its rough starting, its rocking the car when trying to start, the engine sounds rough as, the power steering is getting slightly heavier occasionally and I'm really worried he's messed up the cam belt or done something detrimental to it.

To the point, can I do the AUX belt myself? If so, has anyone got a video I can follow? I have searched, but I wasn't sure if the engine they were working on was the same.

I am OK at doing car stuff, but I am no means a mechanic. So I'm Wary of biting off more than I can chew, but I like to think I'm not completely bad at this stuff.

I also recently lost my job, so this has come at the very worst time.

Any general advise on if there is anything else I should be looking for to make sure my car isn't ruined would be great too.

I've had the car 3 years and have a big ol' attachment to her, this is the first issue we have had and it's unfortunate it's happened now.

Thanks in advance, hope you're all having a good evening

 

[Frostybear]

Sounds like he got the timing wrong on the cam belt? Even though he didn't do the aux belt, wouldn't you just give the car back to him? It's his problem to fix

 

[SuperV8]

When did this rough running start? when you were handed back the keys - or sometime after?

Regarding your aux belt - to remove the belt you need to get under the car and remove the under tray.
You'll need a spanner (16mm from memory) and a locking pin (which you can use a 4mm nail or drill bit) slacken tensioner by going anti-clockwise with the spanner until you can get the locking pin fully seated.
Be careful - there is a lot of spring tension in the pulley - don't put you fingers anywhere they could get crushed if the spanner or pin slip off!

This is the tensioner - to give you an idea of the bolt you need to turn anti-clockwise and the locking pin location.

 

[WillisBruce]

Sounds like he got the timing wrong on the cam belt? Even though he didn't do the aux belt, wouldn't you just give the car back to him? It's his problem to fix

This was my first thought but he is not taking any responsibility for it at all. He is adamant that the problem is with the aux belt and not the cam belt. Not sure what more I can do apart from try and get another opinion

 

[WillisBruce]

When did this rough running start? when you were handed back the keys - or sometime after?

Regarding your aux belt - to remove the belt you need to get under the car and remove the under tray.
You'll need a spanner (16mm from memory) and a locking pin (which you can use a 4mm nail or drill bit) slacken tensioner by going anti-clockwise with the spanner until you can get the locking pin fully seated.
Be careful - there is a lot of spring tension in the pulley - don't put you fingers anywhere they could get crushed if the spanner or pin slip off!

View attachment 51733

This is the tensioner - to give you an idea of the bolt you need to turn anti-clockwise and the locking pin location.
View attachment 51734

Thank you for this, it is very helpful.

When he gave me the car back it had a engine management light on and a lack of power, which wasn't there before. He tried blaming my O2 sensor but that hadn't given me any lights or low power before.

It turned out to be the dpf sensor, after I changed the dpf sensor, the car now had power again. It was still really not sounding happy and the rough starting has got worse gradually since.

My car has given me no problems I told this. I had the coolant leaking problem, but that got solved with a heater matrix change.

I have a timeline of everything that has happened with this repair gone wrong if you wanted it, but it's very long.

I think I'll try this repair myself. Thank you for the detailed reply

 

[SuperV8]

I'm not sure how the aux belt could cause your rough running?
can you scan for fault codes?
I think I would take the belt of - inspect it, and check the tensioner pulley and your alternator pulley. The alternator pulley has a one way clutch - so the alternator should be able to free spin the opposite way.

 

[WillisBruce]

I'm not sure how the aux belt could cause your rough running?
can you scan for fault codes?
I think I would take the belt of - inspect it, and check the tensioner pulley and your alternator pulley. The alternator pulley has a one way clutch - so the alternator should be able to free spin the opposite way.

I'm not sure what's going on with her TBH. I started her today and she took mildly longer to start, but then was fine apart from the squeeling that I think is the aux belt.

The last time I started her the whole car rocked it took a while and then she sounded like a tractor.

I went for a scan today and he scanned it while leaving the car running for a while and it came up with my O2 sensor (that fault seems to come and go, but I will get it replaced ASAP). Then he scanned it again and loads and loads of faults came up, he cleared them, tried again, and then it just came up with "UR112100 databus missing message".

I'm very confused. I'm also very grateful for your replies, so thank you. I think I'll replace the belt and see where we are, I'll get another scan done after too.

When I do take the belt off, what am I looking for? Otherwise I'll take the belt off and be like "yes. This looks belt like " and then replace it.

I'll remember to try and spin the alternator, if it doesn't spin do I need a new one?

 

[Pinky]

Does seem like a wonky sensor to me.

 

[SuperV8]

I'm not sure what's going on with her TBH. I started her today and she took mildly longer to start, but then was fine apart from the squeeling that I think is the aux belt.

The last time I started her the whole car rocked it took a while and then she sounded like a tractor.

I went for a scan today and he scanned it while leaving the car running for a while and it came up with my O2 sensor (that fault seems to come and go, but I will get it replaced ASAP). Then he scanned it again and loads and loads of faults came up, he cleared them, tried again, and then it just came up with "UR112100 databus missing message".

I'm very confused. I'm also very grateful for your replies, so thank you. I think I'll replace the belt and see where we are, I'll get another scan done after too.

When I do take the belt off, what am I looking for? Otherwise I'll take the belt off and be like "yes. This looks belt like " and then replace it.

I'll remember to try and spin the alternator, if it doesn't spin do I need a new one?

Squealing is likely the belt or tensioner, could have just had something split on it?
Assuming the belt's is original (12 years old) - just fit a new one.
When the belt's off, check the tensioner pulley, it should be free and smooth - but should not be able to spin freely, like a skateboard wheel might, also should have no play. I would guess at 12 years old the tensioner pulley is past it's best - so would also be good fitting a new one.

Carefully lock the alternator rotor with a small screwdriver and try rotating the pulley by hand, it should only rotate one direction. If it won't rotate in either direction, or it rotates in both directions you need a new alternator pulley (one way clutch has failed).

Also while the belt's off check the AC pulley is free and smooth.

Are you sure the fault code isn't U112100?
My data suggests this code is linked to adaptive cruise control - do you have it?
Google that code, seems other VAG models have had it - one was a dodgy connector for their ACC.

 

[WillisBruce]

Squealing is likely the belt or tensioner, could have just had something split on it?
Assuming the belt's is original (12 years old) - just fit a new one.
When the belt's off, check the tensioner pulley, it should be free and smooth - but should not be able to spin freely, like a skateboard wheel might, also should have no play. I would guess at 12 years old the tensioner pulley is past it's best - so would also be good fitting a new one.

Carefully lock the alternator rotor with a small screwdriver and try rotating the pulley by hand, it should only rotate one direction. If it won't rotate in either direction, or it rotates in both directions you need a new alternator pulley (one way clutch has failed).

Also while the belt's off check the AC pulley is free and smooth.

Are you sure the fault code isn't U112100?
My data suggests this code is linked to adaptive cruise control - do you have it?
Google that code, seems other VAG models have had it - one was a dodgy connector for their ACC.

The belt should've been changed the last time I changed the cam belt (80k miles), I'm not 100% though, I will need to find the receipt. I'm going to change the belt anyway though, it seems like it could be the problem from what you're saying.

Thank you for your detailed instructions, I've now watched a couple of videos online and I'm pretty sure I can change the belt, although I think changing the tensioner may be too advanced for me. I'm going check it when taking the belt off, as well as the pully like you suggested.

I don't have adaptive cruise control, just the normal kind. I'm thinking the odb reader they were using might be faulty (annoying, as I paid them £20 to use it), so I'm thinking to buy one. Any suggestions on a good cheap but good one? I'm planning to do a lot more maintenance on my car but I'm not "spend lots on tools" wealthy lol.

 

[SuperV8]

The belt is cheap, the tensioner less so. So yes I would just fit a new aux belt - and maybe inspect your tensioner, see what the bearing feels like.

I use "car scanner" app and a bluetooth dongle which works fine for fault codes and live data and is cheap.

 

[WillisBruce]

The belt is cheap, the tensioner less so. So yes I would just fit a new aux belt - and maybe inspect your tensioner, see what the bearing feels like.

I use "car scanner" app and a bluetooth dongle which works fine for fault codes and live data and is cheap.

Thank you mate, you're a massive help

 

[WillisBruce]

The belt is cheap, the tensioner less so. So yes I would just fit a new aux belt - and maybe inspect your tensioner, see what the bearing feels like.

I use "car scanner" app and a bluetooth dongle which works fine for fault codes and live data and is cheap.

Hello mate, I changed the belt today and it was much easier than I expected. I managed to get in from behind the drivers side wheel arch.
The pully would go both ways, but not like a skateboard wheel, so that's ok.
My alternator would go both ways though, you said about locking it, but I wasn't sure what you meant. I think it's ok tbh as I have no battery issues.
The air conditioning one was also ok.
The only one I couldn't move was the massive one, but I'm guessing that comes from inside the engine and runs the whole belt?

Thank you so much for your help mate, I owe you a pint. If you wanna whack me your PayPal I'll happily send you the money for one.

I have one more question for you lol. I've got a squeak from the exhaust when I go above or below 1k revs. I'm guessing it's a emissions flap that's got rusty. Do you know how hard it would be for me to replace this myself?

 

[SuperV8]

Regarding the alternator pulley, it was just a 'while you're in there' check.
The pulley has a one way clutch, so when you lift of the accelerator the inertia of the rotor can keep spinning.
To test you can carefully pop a small screwdriver through the housing to lock the rotor, so then you can try to turn the pulley. It should only turn one way, and the other way should be locked.

I've never had to remove the emission flap on the Leon - but have done exhaust work on other cars and it can be a right pain doing it on a floor jack with very rusty bolts. Each time i'm under a car working on an exhaust I swear to myself this is the last time - and next time i'm taking it to an exhaust specialist!