Whining and jerking; help with diagnosis

[drsb]

I am hoping to make use of a 'wisdom of crowds' approach to diagnosis, or at least narrowing down possible causes of two issues that I fear might be related.

Over past few months I have noticed a steady increase in volume of a whining noise coming from the rear of the engine bay. It matches engine revs not speed, and seems to be loudest on the underside of the car. It is louder when cold, when under load, and especially the day after a long run.

In recent days I have experienced jerky gear changes when the engine is cold. And not just jerky, but hesitating massively and seemingly undecided as to what gear to be in considering speed and throttle position so it seems as if she might go from first to third and then to second, get bogged down, and then accelerate.

I have had a quick skim of the forum, and jerky gear changes seem to be a frequent complaint. But this is more than merely jerky.

Any help gratefully received.

Douglas.

[welwynnick]

Is the gearbox oil level right?

[drsb]

Good question - I have no idea. Is there any way of telling via VCDS, or is it a physical inspection job.

I was told by someone at Audi Huntingdon that the gearbox oil doesn't need servicing on this car, and accepted this advice at face value. From your question and other threads, I believe I have been misled!

[Stiggles]

Good question - I have no idea. Is there any way of telling via VCDS, or is it a physical inspection job.

I was told by someone at Audi Huntingdon that the gearbox oil doesn't need servicing on this car, and accepted this advice at face value. From your question and other threads, I believe I have been misled!

Audi dealers are known for spreading false info on "sealed for life" products. Life should really mean "for your warranty period" as it is absolutely a serviceable item, ZF have a kit for box oil changes.

If it hasn't been changed in it's lifetime, it's 10+ year old oil and should be very high on your list of service asap items!

[drsb]

Thank you Stiggles. Do you have a link for the kit, as a quick search doesn't yield something that is obviously the right kit? It is a 2009 car, with 114,000 miles on the clock - so definitely qualifies.

[Stiggles]

Thank you Stiggles. Do you have a link for the kit, as a quick search doesn't yield something that is obviously the right kit? It is a 2009 car, with 114,000 miles on the clock - so definitely qualifies.

I'm not 100% on which gearboxes we have but I know it's the ZF6HP

ZF direct should be able to supply you, and advise which kit your particular box will need

https://aftermarket.zf.com/go/en/afterm ... ange-kits/

Scroll down a bit and it gives the various 6HP boxes

[drsb]

Wonderful - thank you. And kindest regards ...

[welwynnick]

If you're going to change the filter, I'd suggest going one step further and replace the square O-ring seals that feed and return oil to the valve block. They're one of the few weak points on the ZF 6HP, and if someone's going to get their hands dirty, it's a cheap fix. One of those things that should be replaced every ten years regardless.

Nick

[drsb]

Hey Nice, thanks for the advice. Do you have a part number for the seal? Or are there different boxes even on the C6? Douglas.

[drsb]

For anyone following this thread, the ZF website has a function that will identify your vehicle from its registration correctly (link below).

https://aftermarket.zf.com/go/en/afterm ... /catalogs/#/

In my case, it identifies the right kit (with or without the oil). The kit with oil has the reference 1071.298.027. The ZF link for this is below, but the same reference yields several hits from different providers on Google.

https://aftermarket.zf.com/go/en/afterm ... untryID=GB

The square o-rings that Nick has mentioned are identified as a required supplementary article with reference 1071.298.042. The ZF link is below, but there are several providers.

https://aftermarket.zf.com/go/en/afterm ... untryID=GB

I encountered the dreaded PRNDS error yesterday evening, so she is already at the local specialist for some diagnostics and probable ATF change. Fingers crossed it's nothing more serious than this ...