cliffcoggin

Shane. I am not familiar with that particular engine so I am having to guess a little. The red ringed pipe, (assuming you mean the black rubber hose, not the corrugated metal clad one,) is probably a coolant pipe and looks to have a sizeable split. If that is where the coolant is coming out it must have sprayed all over the engine, possibly shorting out any number of electrical systems. That alone could be why the engine does not fire. The green ringed hose looks to be connected to the inlet manifold or plenum chamber. If so it should only have air in it not oil, indicating turbo wear or damage. That oil also may be a factor in the engine not firing by fouling of the plugs. As I said earlier I am not certain I have identified those parts correctly, so lets wait for confirmation from someone with definite knowledge of the engine. I have to add that although you may not have had a high temperature showing on the dash, there is a real chance that the engine has actually overheated by running it with inadequate coolant. The lack of circulation means the hot water may not have reached the temperature sensor, leading you to mistakenly believe the temperature was fine. I guess you know the consequences for the engine if that is so. Anyone else care to chip in with an opinion?

I fear its wasted advice Richard. The OP has not been back since we gave him advice he did not want to hear.

Have you just bought this vehicle? If so, take it back for a refund as it can not pass an MOT test in its present condition. However if you want to repair it yourself read on. Did you get the toe-in checked when the tyres were renewed? Toe-in is the small angle at which the front wheels point inwards. If it is wrong you can get the vague floaty steering you describe. You also need to check all the steering and suspension joints for slackness with the assistance of another person. One of you should wriggle the steering wheel side to side about a quarter of a turn while the other goes under the car and feels each joint. Really loose joints can also be seen to move, but feeling with your fingers is more sensitive to tiny amounts of play. Any joint with the slightest amount of play needs to be renewed, after which the toe in should be adjusted. While you are it, jack up each front wheel in turn, grab firmly at 9 & 3 o'clock, and rock to and fro while looking and feeling for slack in the wheel bearings. Any loose bearing should be renewed. The coolant warning could be caused by air in the system expanding as the engine warms up and pushing the level up in the reservoir. Is there a visible level change when warm? As for the alternator pulley, test it yourself by releasing the belt tension and rocking the pulley. If it moves it needs to be renewed.

When you say it won't start do you mean it turns over when cranked by starter motor but will not fire, or do you mean it will not turn over? The "split pipe covered in oil" is not a lot of help unless you can positively identify it or send a decent photo.

A prop shaft? The A3 is front wheel drive.

That's awful news Adam. If the battery and the instrument cluster are OK, the only other thing I can think of that would cause these problems is the ECU. That is incredibly expensive to have replaced and not something to be considered until all other avenues have been explored. In your position I would as a first step contact the cluster repairer to explain the problem and see what guarantee they offer. You mentioned that the company began despatch of the cluster the moment you had paid, suggesting that it was either already fixed or they had simply fitted a new fuse without further exploration of the cause of the failure. Depending on the outcome of that discussion I believe you would be at the point of having to decide if it is worth spending much more money on the car. It is possible that another cluster would solve the problem; but equally possible that an ECU is needed. Only you can decide if the financial risk is worthwhile. Not being an electrician myself I am at the limit of my knowledge and can only suggest testing of the car's electrical system by a specialist i.e. not an Audi dealer. Regards Cliff.

The answer is far more mundane Steve, it was a matter of simple economics. My wife found the A3 uncomfortable so all journeys together were in her Yeti. That left me running a moderately powerful 5 seater with me as the only occupant, doing individual journeys of less than 50 miles that totalled less than 2000 miles per year. With a possibly expensive gearbox repair in the offing it made no sense to retain it any longer. So I now drive what I call a Noddy car (Smart EQ). It's not very comfortable and it looks ludicrous, but it's great fun to drive. No road tax, insurance is two thirds of the A3, and only 3 pence per mile fuel cost if recharged overnight on cheap rate electricity. In the light of recent events in Ukraine it looks to have been a good choice.

I am glad to read that the problem is resolved, and thank you for let us know the outcome. It's becoming increasingly rare to be informed of any outcome. As a lifelong cynic I daresay the "we're working on it" message in reality means "it's arrived and we might get round to opening the package soon".

Thank you Steve, I was unaware of that. It's an innovation that has passed me by in the years since I regularly took engines apart. (Having recently changed to an electric car I doubt I shall ever see a big end or a gudgeon pin again.) Am I right in assuming a hydraulic tensioner is supposed to take up the slack as the chain stretches?

The battery is the most likely suspect. Get it proffessionally tested as a first step to diagnosing the problem.

Luke. I am having a hard time understanding a connection between a loose camchain and low oil pressure. I suspect these are two different unrelated problems. If we assume the new camchain is fitted correctly yet you still have a noise and low oil pressure then the problem must lie elsewhere. My first thought would be worn big end bearings or main crankshaft bearings, which rarely fail nowadays unless the oil and filter changes have been neglected. The oil pressure figures you quoted are puzzling. The high pressure at idling speed suggests a pressure relief valve fault or a blockage in one of the oil galleries. That the pressure drops away at higher engine speeds is worrying. One explanation for that would be worn bearings as I mentioned above, though I have to stress that is only speculation at the moment. Some more information might help. What is the mileage of the car? Have the oil and filter been changed at the right intervals? Have you used cheap or substandard oil filters? (The oil filter often contains the pressure relief valve.)

Likely faults are a damaged tyre or worn joints in the transmission.

Electric windows have a sensor to detect if the window is jamming. It's a safety device in case a hand or a child's head is sticking out when the window is closed. In your case I fancy there was a more serious fault than a failed sensor. A piece of glass lodged in the window channel perhaps?

A3s are known to suffer instrument cluster faults. Look back through recent forum history. (I would put a link but the forum software does not allow me to paste a link; it insists on embedding a straight quotation.)

It looks to be swine of a job Rob, yet I see no alternative to somebody getting underneath to remove the EGR valve, and even then there is no guarantee of success. A word of caution for when you visit the mechanic: don't take faults reported by a code reader as gospel. They need to be interpreted by a knowledgable and experienced human brain, else you could be throwing money into a bottomless pit trying to overcome them.

Mark. Repeating word for word what you wrote earlier does not help. We can only work on the information you supply and so far that has been sparse, so I ask again about mileage, coolant loss, EGR and DPF. Additionally I don't see anything terribly unusual about your fuel consumption. Assuming diesel is £1.50 per litre, 150 miles on £30 worth of diesel equates to 150 miles on 20 litres, which equates to 150 miles on 4.4 gallons, which equates to 34.1 mpg. That's not too shabby depending on how the car is driven and how many miles it has done. I never accurately checked my own but I believe it to be 35-40 mpg.

Mark. Whether it was you that had the car mapped or a previous owner is beside the point that it's been mapped. Nobody does that without using the extra power and thus causing extra wear. Be that as it may, it's good you have had some testing done which should eliminate compression and other mechanical faults at the top of the engine, so we can move on to other possibilities. What mileage has the car done? Is it losing coolant? Has the EGR valve been cleaned? Has the DPF been regenerated recently?

As an ex-chemist I do not not believe that anything that survives passage through the engine without destroying it will any effect on carbon in the DPF. The internet is full of such snake oil treatments. This site https://garagewire.co.uk/news/game-changing-dpf-cleaner-is-a-profitable-solution/ indeed suggests that the DPF should be immersed overnight in the cleaner, not poured into the intake.

It sounds as if you have clapped out the engine with your mapping tweaks and some hard driving. Unfortunately a short engine life is the price for high performance.

Marcus. I have not done the job, but given that some A3s had 17 inch wheels instead of the 18 inch that you have at the moment it should be possible to fit smaller wheels with higher profile tyres. You would need to fit tyres of a large enough profile to ensure the overall diameter is unchanged, otherwise it would affect steering/suspension/drive ratios/speedometer.

Rob. I agree with Steve that it is likely to be EGR and/or DPF. How to remove them I do not know as mine is a 2 litre. I believe Gareth has a 1.6 litre so let's hope he will chip in.

That's unfortunate, but the money was not wasted in view of the warnings the car gave you.

But of course, it's Audi we are talking about.

Failure of the stop/start system is another symptom of a faulty battery. Make sure the replacement is suited for stop/start, which requires a better duty cycle than standard batteries can supply.

Adam. A defective battery can indeed cause false warnings in the instrument panel as well as other odd behaviour. It's why I asked about other symptoms. If you have been getting battery warnings recently then I would put money on it, if I was a betting man, being the cause of the false warnings. Your only realistic option is to fit a new battery. Charging the existing battery will not solve the problem.