Air con - ticking under load??

[KitsonRis]

Not quite Clio related but my Octavia vRS (1.8T 20v turbo), feel free to move to a more relevant place! The Skoda forum is a little quiet.
Basically had to change the engine as cam belt tensioner let go. Doing so the air con needed disconnecting. So far I haven't re-gassed it as I wanted to make sure it was all ok first. It is the only thing that hasn't been reconnected.
But I have this ticking noise that gets louder under load, have to rev it more when stationary but very noticeable when driving. Noise is coming from the aux belt side of the engine and it does sound as if it is a driven item, like a pulley/bearing and not from the engine itself.
Having no fluid/gas in the system, would this be a problem? As the aux belt is still driving the air con pump, but the air con isn't switched on. Other than that, no idea what this noise is!!!
Anyone experienced anything similar??

 

[Ads29]

It's been a while since I last had a VAG family vehicle but from memory the AC pump should have a clutched pulley, so when the AC is switched off the pulley just freewheels and acts as am idler until being switched back on.

A gain its from memory but do you have an auto tensioner on the aux belt? Is there NY vibration in that causing the noise?


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[imprezaworks]

@TomSx
@Scrooge

 

[Scrooge]

Yep AC pump had a clutch. So as long as it's not switched on it won't be engaged. Without seeing it it could be a shitload of things tbh

 

[KitsonRis]

What I didn't think of doing was removing the aux belt and driving up the road a bit (only has air con, power steering and alternator on the aux belt). The tensioner is new so sure it isn't that.
I had more of a google last night and there are a few more things to check....turbo to exhaust gasket, possible carbon canister valve or something and possibly pinking from the timing being ever so slightly out (replaced can belt on the replacement engine before going back in). If the exhaust gasket is ok I am going to drop it at a specialist to have their opinion and check the timing.
The car wasn't making this noise before and the donor car was silent too. So it is something that I've done.
This car is more complex than the Clio!!

 

[_Tom]

As Scrooge says it could be many many things. A loud ticking under load can very often be the exhaust gaskets as you say but it doesn't make sense to be coming down from where the aux belt is. It's more like to be a pulley. Carbon canisters tick but it wouldn't get louder under load.

 

[KitsonRis]

I am hoping it is exhaust gasket, going to check after work later.
When in the car it sounds like it is from behind the steering wheel area, that's why it think it is down by the aux belt and thought possible air con. This is where the intercooler and some turbo pipe work is. Tried to check it lat night but hard when led under the car in the rain. It's hard to hear/make it do it when stationary and revving. But when driving it is very noticeable, it's like that extra load of driving it makes it worse. Which could suggest possible turbo (my initial thoughts when I first noticed it).
Just trying to eliminate things and get things to look at later before I get bored and fix the car with a can of petrol and a match.

 

[Icarus83]

I am hoping it is exhaust gasket, going to check after work later.
When in the car it sounds like it is from behind the steering wheel area, that's why it think it is down by the aux belt and thought possible air con. This is where the intercooler and some turbo pipe work is. Tried to check it lat night but hard when led under the car in the rain. It's hard to hear/make it do it when stationary and revving. But when driving it is very noticeable, it's like that extra load of driving it makes it worse. Which could suggest possible turbo (my initial thoughts when I first noticed it).
Just trying to eliminate things and get things to look at later before I get bored and fix the car with a can of petrol and a match.

Possibly not related but might help.....

My A4 (B6 1.9TDi) has a chattering noise when the AC pump is off, but occasionally when on, and the reason for it is there are six two prong rubber 'bumpers' within the front pulley/clutch wheel. works a little like a dual mass flywheel with rubbers rather than big springs. My rubber bumpers have perished and worn away. Might be worth looking into.

Ironically the noise sounds like a failing dual mass flywheel...

I did the remove aux belt then ran the engine trick to identify if it was engine or ancillaries, and it proved it wasnt engine side for me. Phew!

There is the other option that its the flyaway clutch pulley on your alternator (but that tends to squeal rather than tick).

Finally, my turbo made a rattling/ticking noise for a few months before it went pop, but that was after accelerating hard and letting off when it made the noise.

 

[KitsonRis]

Possibly not related but might help.....

My A4 (B6 1.9TDi) has a chattering noise when the AC pump is off, but occasionally when on, and the reason for it is there are six two prong rubber 'bumpers' within the front pulley/clutch wheel. works a little like a dual mass flywheel with rubbers rather than big springs. My rubber bumpers have perished and worn away. Might be worth looking into.

Ironically the noise sounds like a failing dual mass flywheel...

I did the remove aux belt then ran the engine trick to identify if it was engine or ancillaries, and it proved it wasnt engine side for me. Phew!

There is the other option that its the flyaway clutch pulley on your alternator (but that tends to squeal rather than tick).

Finally, my turbo made a rattling/ticking noise for a few months before it went pop, but that was after accelerating hard and letting off when it made the noise.

I've booked it into the local VAG specialist as I am at my wits end with it. Hoping their just hear it and know exactly what it is.
It's got a new alternator so presume it isn't that. Also the turbo is off the original engine as I knew it was good. Both cars were not making this noise before the swap so I'm thinking it's something I've done/not done

Thanks for the heads up though.