cliffcoggin

A. See my reply to your other query.

A(nonymous). Given that this thread is over seven years old it is unlikely you will get a response from the originator. Nevertheless there are some useful suggestions in it. Have you tried any of them?

There is no way to check for wear without dismantling the engine, by which point one might as well change the belt anyway. The labour cost of that work is why it so expensive, and also why it is prefeable to change the water pump at the same time. Whether you have a belt or a chain can only be determined by reference to the engine number or VIN as Magnet suggested.

To go 12 years without a belt change is fortunate. Depending on which engine you have, it may be suggested by the garage to fit a new water pump at the same time. That will add to the cost but is worth doing.

Bill. The Audi service schedule is more or less all you need do to keep it in decent condition, though I would add two caveats: 1/ Change the cambelt ahead of schedule if it has not been replaced for a few years. Even though the car may not have reached the recommended mileage, (you have not mentioned the actual distance covered since the belt was last changed,) belts can degrade even when not used. Given the consequences of belt failure abroad it makes sense to my mind to change it in advance. 2/ Take the car for a fast motorway journey of about half an hour well before your next continental holiday. That will reveal any faults that may need to be sorted out before you go abroad.

Syed. All I hear in the first and second videos is the normal diesel clattering. I don't hear even that in the third video. Unless you have other symptoms of engine problems you have nothing to worry about.

Syed. I do not download anything from untrusted sources, so if you would care to put your videos on Youtube or similar I'd be glad to listen them there.

Ditto what Gareth wrote. Let me add that it is always wise to change the water pump belt at the same time as the cambelt because the same expensive work is needed to access them both.

Glad to read that. Common sense and a inquisitive mind can solve more problems than any amount of computer diagnoses. Regards, Cliff, a one time chemist with absolutely no electrical qualifications.

Dave. Your error codes are still showing a short circuit or open circuit, just as they did two months ago when I suggested there was either water present or a broken connection. You will need to get a meter (and learn how to use it,) or take the car to somebody electrically proficient because tugging at the wires will not reveal the exact location of the fault.

Magnet, who is one of the regulars here, often suggests https://www.partsinmotion.co.uk/ I have never needed to use the company so I have no idea about its service.

Emma. I don't know these particular parts, but it would be worth investigating a secondhand heater matrix from online car breakers.

The fluid behind the pedal is because the cylinder is leaking, as I mentioned earlier. It's a common problem on old hydraulic systems and nothing unusual. A secondhand master cylinder is, to put it politely, unwise. To put it less politely, it is downright foolish to fit equipment that not only may leak as badly as the original, but could in fact fail to work at all when you most need it in an emergency. You may be willing to risk your own life, but please consider the lives of other people in and around the car.

Dan. The brake master cylinder is defintely leaking and needs to be repaired or renewed. I don't see why there should be fluid in the servo but it would not hurt to check.

The low oil consumption suggests the engine is in reasonable condition for its age, and in standard form would likely not have high CO emissions. Therefore I'd say your modifications are responsible for the problem, and the solution is to restore the engine to standard form.