I've had a range of interesting noises from my Octavia now it's nearing 160,000 miles. I've cured the most obvious grinding noise with a new o/s front wheel bearing. The resulting 'chuffing' noise then turned out to be the hub nut not fully tightened.

Now that's all sorted, I'm hearing something else. Foot down, it's fine. Rev to about 3,500 rpm while driving, then lift off and coast. As the revs get to 3,100 rpm there's a metallic squeal from the engine. When it gets to 3,000 rpm it stops. The only thing I can liken it to is drilling into a big block of metal.

The first time I heard it I was coming off a slip road on to the A1. I think I was at a speed which would coincide with about 3,100 rpm. I think there was a metallic burning smell as well, but I'm not sure.

I'm not limited to 50 mph and the turbo is definitely still spooling up and giving boost. Any ideas?

J

I'd be checking out the cambelt and tensioners I think.

When was the belt last changed and did they use a full kit including new tensioners and rollers or just a belt?

Sometimes these noises turn out to be loose heatshields, etc, vibrating when you hit their resonant frequency.

If you hold the revs at 3100 does the noise continue?

Can you reproduce the noise whilst the car is stationary?

Equally, if it's a resonance issue, it'll prove to be reproducable in all gears, not just top.

Thanks for the input guys.

The belt was last done by a main dealer. That's all I know. It's due again very soon. The auxilliary belt was done 20k ago.

You can't reproduce the noise when stationary but it does happen in third and fourth. You get 'chirping' at other times too - the same noise I think but much shorter. Bumps seem to cause chirps. I can prolong the noise by holding the revs.

Isn't the cambelt toothed? I didn't know it could squeal. The aux belt appears to be flat. Which belt is the water pump on?

J

Equally, if it's a resonance issue, it'll prove to be reproducable in all gears, not just top.

:eek: Over 3,100rpm in top is into three digits!

Isn't the cambelt toothed? I didn't know it could squeal. The aux belt appears to be flat. Which belt is the water pump on?

Cambelt is toothed and drives the water pump.

:eek: Over 3,100rpm in top is into three digits!

For no adequately explored reason I read this as being on a petrol!!!

Seriously though, I'd never see 3_100 in any gear on an exit slip in a TDi unless I was braking from over a ton on what I knew to be a long slip in Germany.

For no adequately explored reason I read this as being on a petrol!!!

Seriously though, I'd never see 3_100 in any gear on an exit slip in a TDi unless I was braking from over a ton on what I knew to be a long slip in Germany.

It wouldn't be unusual for me to drop into fourth from motorway speeds as I went up an exit slip. But in this case, it was an entry slip. The slip roads on the the older parts of the A1 are so short, you need to be able to adjust your speed pretty quickly to slot in.

Anyway, it sounds belt related and it's due a cambelt in 2000 miles, so I'll probably just get it booked in and sorted sometime over the next week or two. I'll let you know what happens.

J

There are tensioners and rollers on the cambelt as well as the waterpump.

If you're unsure I'd get it looked at asap and when you do the cambelt have all of these changed and also the water pump.

It was an entry slip. The slip roads on the the older parts of the A1 are so short, you need to be able to adjust your speed pretty quickly to slot in.

Fair enough; I do the same sort of thing too. In fact it's bad driving to do otherwise.

Anyway, it sounds belt related and it's due a cambelt in 2000 miles, so I'll probably just get it booked in and sorted sometime over the next week or two. I'll let you know what happens.

J

If you suspect the cambelt is on its last legs, try not to use the car until it's sorted!

Well the cambelt didn't fix it! I've been told it's an exhaust bracket that's gone.