2.0 T FSI Quattro - Knocks like a diesel

[snoopster]

Just bought a 2.0T FSI quattro. I thought this was a petrol car but it sure sounds like a diesel.

Knock only occurs when the car has warmed up.

Knock is present at idle (no load) and higher revs, and does not get louder with load.

Knock has been located to top of engine, induction camshaft side.

High pressure Fuel pump cam follower was suspected and has been changed. The old one was in perfect condition but garage failed to check lobes on camshaft. Suspect that if follower was OK then so is the cam for driving the pump.

It does not sound like an injector noise.(more a knocking noise than ticking injector noise and also a lower frequency than injectors)

It does not sound like an combustion noise.(lower frequency)

What can it be? I have heard a similar noise on an Alfa TwinSpark inlet camshaft when a cam lobe wears with the same destructive effect on the cam followers.

This car has only done 45k, surely the camshaft is OK?

Has anyone experience of resolving this kind of problem?

[snoopster]

I see many viewers of this posting, but no contributors which suggests many may have this problem bnut few have solved!

Well 6 months later and this was solved and the reason was somewhat unexpected.

In short the cambelt replaced by the AUDI dealer at the 40k service was fitted with the belt out by one tooth! Since being replaced the knocking has stopped, fuel consumption has improved from 26 to 32 mpg, and pinking under load has stopped.

Also noticed was that the dealer had only replaced the belt and water pump but had not chosen to replace the tensioner pulley or belt rollers. 5k miles later when i took over the vehicle these had become noisy and were showing signs of blueing 'overheating'.

So in summary,
1 tooth out on the belt (exhaust cam had been rotated clockwise by 1 tooth) will cause a knocking but not valve damage.
Dealers not always that good on belt changes and will skimp on parts they replace (this is based on experience with West London Audi and does not necessarily apply to all Audi dealers)

[Crasher]

I am staggered an Audi dealer has done that and I suspect it will be an individual rouge grease monkey that is responsible, no contentious mechanic would allow that to happen. The noise will have been valve to piston contact, that is has survived is astonishing and I am also surprised the MIL did not come on and store a cam phase error in the ECU.

[snoopster]

I am staggered an Audi dealer has done that and I suspect it will be an individual rouge grease monkey that is responsible, no contentious mechanic would allow that to happen. The noise will have been valve to piston contact, that is has survived is astonishing and I am also surprised the MIL did not come on and store a cam phase error in the ECU.

Well I would suspect valve to piston contact but the knocking was most certainly restricted to piston 4 end of the block up by the timing chain and cam timing adjuster. If this was valve to piston contact then it should be heard on all pistons. I suspect the knock noise maybe related to cam timing adjustor desparately trying to compensate for the timing error. And just to confirm, no MIL or cam phase errors on VAGCOM. Also interestingly no loss or gain of power before or after timing correction, just improvement in fuel economy.

Over to dealer side of story (maybe should be another forum subject?), they refused to correct the issue as it was out of their 12 month workmanship warranty period but were happy for me to transport it across london for them to inspect. They knew full well the cost of this would exceed the cost of the audi specialist to resolve. They also refused to allow Jack Barclay (Audi/Bentley dealer 100 yds away from vehicles location) to inspect it on their behalf.

Over to the Audi UK side of the story, they did not want to get involved, re-quoting the 12 month excuse and supporting West London not having Jack Barclay inspect on their behalf (When it comes down to it they are just independant franchises). But what really worried me was Audi UK tech dept could not confirm whether being a tooth out on the exhaust cam could bend valves. Obviously if this was confirmed it would have been on a transporter over to West London Audi straight away!

[Crasher]

I was under the impression that the warranty was 24 months.