Strange rattle noise on spesific low revs.

[Jojjo]

Hi.

First post at this forum...

I don't have a Scirocco yet, but as this is engine related, I hope to get an answer here. I'd like to buy one though, but it doesn't suit the wife, 3 kids+dog model right now. My Tiguan from 2008 with the CAVA/BWK twincharger engine has developed a strange rattle noise, which is very annoying. It has been there for a year now, and I can't find the answer to the problem... The sound can be described as a combination of a diesel engine and a heat shield resonance. It has no performance drawbacks.

The car is a 1.4 twincharger petrol with a 6 speed manual gearbox - not a diesel, and the noise is coming from the rear / driver's side of the engine (I have the steering wheel on the left side) - opposite of the timing chain.

This is how the rattle noise is working:
- It is only present between 1500 and 3500 rpm. It is also erratic, but vanishes completely at 3500.
- It is not entirely related to load, and is present at both hard and extremely slow acceleration. Hard acceleration makes the noise (diesel clatter) louder.

Here comes the tricky part. Lets just say I drive the car in 3rd gear, doing 60 km/h (43 mph or so), then rolling downhill. If I let go of the clutch (foot resting), car rolling in neutral, rev the engine quickly to 6000 rpm, the noise is not there at all. Just a smooth 1.4 litre petrol. Then (still rolling in neutral, not any gear engaged - manual gearbox) I press the clutch all in, the same rev - and the diesel clatter is there. It is completely gone at 3500 rpm though. In gear it is always present in the giver rev range.

I am completely lost here, and as there are very few 1.4 Tiguans, I hope for a reply here. Everything seems alright and tightened and impossible to trace. It has to be either transmission related (mechanic) or ignition (electronic) or a combination. It sounds like something is loose until I reach 3500 rpm, but all heatshields are ok. Lets say you whip cream with a mixer, and you strike the sidewall of the bowl with the rotors, that's the erratic noise (multiplied many times).

I now have a new tensioner, chain kit, waterpump and compressor clutch, N75 valve, a complete new clutch kit, with flywheel and throwout bearing. The noise is still the same.

I am wondering if the clutch is sending an electronic signal to the ECU to tell the engine to behave in a given way regarding the clutch is in or out when it comes to ignition timing or fuel injecting. Rolling downhill with the gear i neutral and foot off the clutch, revving is smooth, pushing my left foot all in on the clutch, and the rattle is present. The car works great though.

I had an idea it was the turbo charging, as 3500 is appx where the supercharger function switches over to the turbo, but the noise is not present in the turbo area. But how can the clutch play any role in this?

Regards, Morten.

[Nish108GP]

Hi.

First post at this forum...

I don't have a Scirocco yet, but as this is engine related, I hope to get an answer here. I'd like to buy one though, but it doesn't suit the wife, 3 kids+dog model right now. My Tiguan from 2008 with the CAVA/BWK twincharger engine has developed a strange rattle noise, which is very annoying. It has been there for a year now, and I can't find the answer to the problem... The sound can be described as a combination of a diesel engine and a heat shield resonance. It has no performance drawbacks.

The car is a 1.4 twincharger petrol with a 6 speed manual gearbox - not a diesel, and the noise is coming from the rear / driver's side of the engine (I have the steering wheel on the left side) - opposite of the timing chain.

This is how the rattle noise is working:
- It is only present between 1500 and 3500 rpm. It is also erratic, but vanishes completely at 3500.
- It is not entirely related to load, and is present at both hard and extremely slow acceleration. Hard acceleration makes the noise (diesel clatter) louder.

Here comes the tricky part. Lets just say I drive the car in 3rd gear, doing 60 km/h (43 mph or so), then rolling downhill. If I let go of the clutch (foot resting), car rolling in neutral, rev the engine quickly to 6000 rpm, the noise is not there at all. Just a smooth 1.4 litre petrol. Then (still rolling in neutral, not any gear engaged - manual gearbox) I press the clutch all in, the same rev - and the diesel clatter is there. It is completely gone at 3500 rpm though. In gear it is always present in the giver rev range.

I am completely lost here, and as there are very few 1.4 Tiguans, I hope for a reply here. Everything seems alright and tightened and impossible to trace. It has to be either transmission related (mechanic) or ignition (electronic) or a combination. It sounds like something is loose until I reach 3500 rpm, but all heatshields are ok. Lets say you whip cream with a mixer, and you strike the sidewall of the bowl with the rotors, that's the erratic noise (multiplied many times).

I now have a new tensioner, chain kit, waterpump and compressor clutch, N75 valve, a complete new clutch kit, with flywheel and throwout bearing. The noise is still the same.

I am wondering if the clutch is sending an electronic signal to the ECU to tell the engine to behave in a given way regarding the clutch is in or out when it comes to ignition timing or fuel injecting. Rolling downhill with the gear i neutral and foot off the clutch, revving is smooth, pushing my left foot all in on the clutch, and the rattle is present. The car works great though.

I had an idea it was the turbo charging, as 3500 is appx where the supercharger function switches over to the turbo, but the noise is not present in the turbo area. But how can the clutch play any role in this?

Regards, Morten.

Hi Morten

Have you taken a look at the plate that shows the vin number through the windscreen. Mine was loose and sounded like what your are describing.

Sent from my SM-A520F using Tapatalk

[tSeL]

Could be the high pressure fuel hoses that tend to make a noise when they sync,vw usually fixes that by putting a sponge in between them


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[Jojjo]

Hi Morten

Have you taken a look at the plate that shows the vin number through the windscreen. Mine was loose and sounded like what your are describing.

Sent from my SM-A520F using Tapatalk

This is engine related. After servicing my own Fiats for over 15 years, I am used to cockpit rattles, but this one is tricky. It is also a bit difficult at the garage, as they are VW specialists. They just follow pre-defined procedures, they aren't what a mechanic used to be, so they have no clue... But they accnowledge the noise.

Regards, Morten (Tromsø, Norway).

[Jojjo]

Could be the high pressure fuel hoses that tend to make a noise when they sync,vw usually fixes that by putting a sponge in between them

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Yes, the sponge fix is done, but my fuel hoses comes from the left side ( when looking into the engine bay). They noise is from the right, perhaps rear-right. I have been thinking if the high pressure fuel pump or cam follower if the engine has this. But why does the noise stop where the turbo takes over from the compressor?

Is the fuel pump or injectors perhaps working differently when the clutch is in or out?

Regards, Morten (from the cold north).