cliffcoggin

I have never heard a gearbox make the sort of sound you describe, but if it is the box it is probably too late to do anything about it. Nevertheless for peace of mind it won't hurt to get the oil changed.

Stephen. All your voltage readings tell you is that the alternator is working and that there is not a short circuit in the battery. They tell you nothing about the condition of the battery in regard to sulphation of the electrodes or the formation of dendrites which cause loss of capacity and an inability to hold a charge. To do that requires equipment that most owners do not possess so I suggest you get it professionally tested. As to coding, I have read (though I can not recall the source of the information,) that all VAG cars from 2008 require it, and some earlier models too. (My 2007 A3 did.) Uncoded new batteries will still work for a while though their lifespans will be shortened because of wrong charging rates. Incidently loss of radio presets and false dash warnings are symptoms of a battery that is dying. See this post: https://www.audiownersclub.com/forums/topic/28121-ignition-light-disco/#comment-113216

The EGR cooler is a common location for invisible coolant losses. It's quite an expensive job I believe.

Larry. All I'll say at the moment is that wheels are in motion.

It happens all too often unfortunately. Both common courtesy and the forum rules require some sort of aknowledgement from the questionner to responses he has received. In this case Ma has not even looked at the forum since posting his question.

It's hard to be sure without actually hearing the sound, but your description suggests one or more of the brakes is either not releasing properly or there is debrid trapped between disc and pad. Does the noise change when the brakes are firmly applied?

In that case I suspect the engine is misfiring. All the more reason to return it to the dealer without delay.

I can't really add any thing without more information. Perhaps I did not state my questions clearly enough, so let me start again. [1] What is the engine speed, not the road speed, when the vibration occurs in 5th gear? [2] What is the engine speed, not the road speed, when the vibration occurs in 4th gear?

You may well be right for all I know. My point was more that if the master cylinder seals are perished then the slave cylinder seals will also be in poor condition and liable to let go in the near future, so it makes sense to my mind to do both at the same time. I have always believed that if you do a job properly, you only do it once; whereas if you do a job poorly it will have to be done again. Anyway that's a decision for Mohame to make. We have presented him with two options to choose from, both equally valid for different reasons.

I think we can eliminate front tyre balance. That still leaves rear tyre balance, loose wheel nuts and a host of other possibilities. What is the engine speed when the vibration occurs in 5th gear? What happens when you drive the car in 4th gear at that same engine speed? On reflection I re-read the question and realised you have just bought the car from a dealer, so my response changes to take the thing back and let him resolve the problem free of charge.

I suggest you renew both the master cylinder and the slave cylinder. It may be that only one is defective at the moment, but at 13 years old the other will soon follow it into retirement.

Mornington Crescent.

Like Magnet I would go with the suppliers recommendations rather than be guided by what you have in the car at the moment, which will undoubtedly have been renewed a few times in an 18 year old car.

I'd agree with Steve Q. Old software and maps should not affect the ability of the sat nav to detect satellites, even if it can not use the satellite data.

Derrick. Where do you feel the vibration, at the steering wheel or through the seat?

Allow me to put my chemist's hat on again. Silicones are the best thing for plastics and rubbers because they do not soften or dissolve them, unlike mineral oils, however they are much more difficult to remove than mineral oils. If you have ever smeared silicone mastic on a glass shower door it will be forever water repellant.

Good guess. See this https://www.audiownersclub.com/forums/topic/24906-alternator-failure-related-to-mild-hybrid-system/ Yours is a similar model but the technology will be the same.

Oh I have in the past. The manufacturer is notoriously tight lipped about the constituents of WD40. All one can get out of them is the MSDS (material safety data sheet) which reveals only that the solvent is similar to white spirit. https://sichdatonline.chemical-check.de/Dokumente/3275/EUF-0002_0012_27-02-2024_EN.pdf As a chemist in a past life I recognise that WD40 is a mixture of oil, white spirit and a powerful perfume to cover the solvent stink. I suspect it also contains drying agents to congeal the oil. Drying agents were commonly used at one time in oil based paints and varnishes. (I used to be involved in the manufacture of two such agents: cobalt siccatol and manganese siccatol so I know a little about them.)

I have to agree with Mark on this matter. WD40 is evil stuff that slowly congeals to a sticky muck that frequently makes the problem worse. If you get to it before it has completely dried you can free it by adding more WD40. It is like becoming addicted to a drug in that once you start using it you have to keep buying more. What a wonderful strategy to increase sales! Despite the manufacturers claims, WD40 is a poor lubricant. Bear in mind it was developed as a rust preventative because of its water displacement properties, (hence the WD in its name,) which require it to dry to a firm well adhered coating on steel. That's the last thing you want from a lubricant.

Glad to hear it's sorted. Giddy up Neddy.

It might be the hydraulics that operate the clutch. At what point in the pedal travel does the clutch start to bite or grip? It should be about half way. If it bites close to the floor you have a problem with either the master or slave cylinder.

What news on this Lee? Have you had the battery tested or renewed?

Roshan. Was the information in the linked video of use to you?

In that case I suspect a fault in the car.

What was the state of charge when you began recent charging sessions? Are you aware that the charge rate will drop considerably as the SOC approaches 80%? It is usually said that it takes as long to charge from 10% to 80% as it does to charge from 80% to 100%.