Timing chains AGAIN!!!

[archboldm]

Hi guys,just wondered if someone could shed some light on something for me.I read regularly about the noise on startup on the S4,mine does it as well,however,reading the S6 & RS6 sections,rarely gets mentioned.Is this problem perculiar to our models only,& if so,why?

[tweek]

Interesting, the only thing I can think of is the S4 is the only V8 that has 40 valves, all the other V8's only have 32 valves. There must be something different in the chain drive mechanism, if you have ever tried to turn an engine over by hand and felt the pressure caused compressing the valve springs, this spring pressure gets forced back into the chains and the tensioners and probably gives the tensioners a tougher time when the engine is running.

It may be that the back pressure from the extra valve per cylinder is too much and the tensioners have a higher failure rate, would be curious to know if the tensioners that fail are the one around the cams? Curious that the new V8 engines are all 32v. This is only my view of what could be the cause and maybe completely wrong, comments welcome.

Pete

[archboldm]

Valid point Pete,in my ignorance,I thought the S4 & S/RS6 ran the same engine.But if that's not the case,maybe that explains it!!! many thanks for your input
Mac

[B6S4John]

The RS6 and S6 have a different V8 that had cam BELTS. Only the S4, new RS4 and R8 have the camchains because it needs to be more compact.

[archboldm]

cheers mate,wondered how they shoehorned it in there??

[B6S4John]

cheers mate,wondered how they shoehorned it in there??

This is what they look like. They are on the back of the engine.

[tweek]

that picture nearly stopped me buying one...still would like to know if there is a particular tensioner that causes the trouble or is it all of them?

Pete

[archboldm]

GOD, that looks like a complete nightmare !! Glad i've got warranty direct !!!

[tweek]

The timing chain problem was one reason (of many) why my first S4 went back for a refund which I got in full.The replacement is much much better..

Pete

[else]

I've had all the tensioners and chains replaced under warranty and it's exactly the same, no improvement.

I personally think its something to do with the variable valve timing gear because when it makes the noise the engine also misfires a few times, I've got a Milltek exhaust so its easy to hear .

We are waiting for the results of an investigation by Audi Germany before the next move. Maidstone Audi have been absolutely brilliant through all of this, i just hope that it gets sorted soon, its so embarrassing when it happens in public, sounds like an old tractor for a couple of seconds

Else

[archboldm]

I know what you mean mate,in spite of all the reassurances on all the forums,when you hear it,you think,that CANT be normal !!!

[archboldm]

Plus,my previous car,a VW passat W8 with all chains,did not make any noises on startup & it's got 95k on the clock ??

[else]

Hi Mate,

Whats your LPG conversion like to use, Pro's and Con's ?

Else

[archboldm]

Hi Else,Sorry I didn't reply earlier,I have not had the Job done yet,It is booked into CLS dual fuel at the end of this month,when I have had time to assess it,I will post a thread.
Mac

[Mockenrue]

Interesting, the only thing I can think of is the S4 is the only V8 that has 40 valves, all the other V8's only have 32 valves. There must be something different in the chain drive mechanism, if you have ever tried to turn an engine over by hand and felt the pressure caused compressing the valve springs, this spring pressure gets forced back into the chains and the tensioners and probably gives the tensioners a tougher time when the engine is running.

It may be that the back pressure from the extra valve per cylinder is too much and the tensioners have a higher failure rate, would be curious to know if the tensioners that fail are the one around the cams? Curious that the new V8 engines are all 32v. This is only my view of what could be the cause and maybe completely wrong, comments welcome.

Pete

It is my understanding that the new V8s all have 32v because they are FSI, with one valve per cylinder replaced by the FSI injector.