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Discussion Starter · #1 ·
Hi everyone,

Have had my 52 plate ZT for just over a week now and think I may have a couple of problems.

Firstly, I've noticed what seems from inside the car to be a growling sound at around 2000 revs. Tonight whilst on my way to work I had the window open and rather than hearing the growl heard a distinct metallic rattle. I'm fairly sure that it disappears once the engine has heated up but it does have me a tad worried.

Secondly, very soon after starting the engine (about a minute if not less) I can hear what sounds like a fan starting up which continues until about 30 seconds after I've stopped the engine. The only thing I can think this is is the fan on the radiator. Should this be starting up so soon?

As the car still has a years manufacturers warranty left on it I'll probably get it back to the dealer to get them to investigate but am worried that I'm having problems so soon after buying the car>

Any advice would be appreciated.

Thanks in advance

Alistair
 

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Advocate said:
Firstly, I've noticed what seems from inside the car to be a growling sound at around 2000 revs. Tonight whilst on my way to work I had the window open and rather than hearing the growl heard a distinct metallic rattle. I'm fairly sure that it disappears once the engine has heated up but it does have me a tad worried.
Is yours the V6 or 1.8T?
I would definately get this noise investigated by the dealer.

Advocate said:
Secondly, very soon after starting the engine (about a minute if not less) I can hear what sounds like a fan starting up which continues until about 30 seconds after I've stopped the engine. The only thing I can think this is is the fan on the radiator. Should this be starting up so soon?
If you have the aircon switched on, the fans will be on. Mine switch off as soon as the engine is stopped.
 

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Discussion Starter · #3 ·
Thanks for the reply mate. Forgot to mention mine is the 1.8T, I'm pretty sure this sounds like a vibration rattle but seeing as though the car is under warranty do you think it makes sense to get it back to the dealer for investigation? [EDIT] After sitting playing with the throttle once home this morning I can confirm the rattle starts at between 1000-1500 revs, disappears at 2000 but I hear a small rattle when letting off the throttle[/EDIT]

As for the fan noise, i hear it even when the aircon is switched off. Having said that, I can't honestly say I heard it when coming home from work though I have heard it often on short journeys.
 

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Hmm, dunno mate. It's difficult to comment when you can't hear it for yourself. Its not an exhaust rattle is it? Mine has a slight exhaust rattle at low revs.

Someone who has a 1.8T may be of more help.

Take it back to the dealer, if you're not happy.
 

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REDevil said:
Hmm, dunno mate. It's difficult to comment when you can't hear it for yourself. Its not an exhaust rattle is it? Mine has a slight exhaust rattle at low revs.

Someone who has a 1.8T may be of more help.

Take it back to the dealer, if you're not happy.
I'd agree it could be the exhaust. Maybe the catalytic convertor cover has become a bit loose?
 

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Advocate said:
Firstly, I've noticed what seems from inside the car to be a growling sound at around 2000 revs. Tonight whilst on my way to work I had the window open and rather than hearing the growl heard a distinct metallic rattle. I'm fairly sure that it disappears once the engine has heated up but it does have me a tad worried.

Secondly, very soon after starting the engine (about a minute if not less) I can hear what sounds like a fan starting up which continues until about 30 seconds after I've stopped the engine. The only thing I can think this is is the fan on the radiator. Should this be starting up so soon?
1. If its a 1.8T that'll be the turbo. Mine used to do it. The chattering you can hear is the wategate/turbo being stalled as the throttle butterfly closes.

2. That noise is to do with the air-con/climate control and, yes, its normal. All three of our 75s/ZTs have/do it...
 

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Try switching all the Air Con / Climate off and see if it still does it...

Turbo / Wastegate does chatter a bit... sounds normal...
 

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Discussion Starter · #8 ·
Now that I'm out of bed (I hate nightshifts) I'll go try running the engine with the aircon off. Can't recall hearing the fan noise this morning on the way home but then I did turn the aircon off so that the noise of that wouldn't interfere lol

Thanks for the reassurance everyone. These forums are now first on my list of sites to browse every day thanks to the warm welcome people get here.

Alistair
 

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Discussion Starter · #9 ·
[UPDATE] Have just had a trip to the shop and made sure to go the long way to warm her up adequately. Left the aircon switched off and lo and behold no fan noise when I stopped the car :D Switched the aircon on on the way home and the fan noise was back, so that's that one solved.

Regarding the rattle, if it is Turbo/Wastegate chatter (I so wish I knew what that was :s) would it still rattle when decelerating with no throttle as it passes through 2000 revs? [/UPDATE]

Thanks again peeps, the more I drive my ZT the more I love it :D:D
 

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Advocate said:
[UPDATE]Regarding the rattle, if it is Turbo/Wastegate chatter (I so wish I knew what that was :s) would it still rattle when decelerating with no throttle as it passes through 2000 revs?[/UPDATE]
The turbo is an impeller/compressor arrangement, which needs to spin up to speed, when you take your foot off the throttle the compressed air has nowhere to go and so the turbo stalls and the wastegate opens to relieve the pressure - as the pressure then goes the wastegate closes - the pressure builds again and once more the wastgate opens. This open/close cycle is what you can hear. The wastgate also opens if there is too much pressure when accelerating (to stop the engine blowing-up).
 

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Discussion Starter · #11 ·
r44712 said:
The turbo is an impeller/compressor arrangement, which needs to spin up to speed, when you take your foot off the throttle the compressed air has nowhere to go and so the turbo stalls and the wastegate opens to relieve the pressure - as the pressure then goes the wastegate closes - the pressure builds again and once more the wastgate opens. This open/close cycle is what you can hear. The wastgate also opens if there is too much pressure when accelerating (to stop the engine blowing-up).
Thanks for that excellent explanation :)

So basically I'll get the chatter both when revs are on the way up and the way down?

I may get my mechanic friend to have a look/listen to see if he agrees (hardly ever see him nowadays so will have to make special arrangements).

Thanks again mate :)

Alistair
 

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also worried....

I too was a little worried until I read the comments from R44712.

Just bought my first turbo powered car with the ZT-T model so don't know too much about turbo's. Although I cannot hear any noise as the power comes on, I can definitely hear something when the revs back off at around 3000 RPM during gear changes up though the gearbox.

Took the car to the dealer as it's still under warranty, where the mechanic said not to worry as it's normal. I did worry until I read of similar problems in the member's forum - a little happier now.

Thanks for letting me listen in on the chat.

Robert
 

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Is the noise like a low vibration? Mine does this at low speeds sometimes and its the shield under the engine. It might need an adjustment.

The turbo noise tho will give you a whistling noise, rather than a rattle/vibration.

Just to advance on r44712 ;)

The wastegate controls maximum boost pressure and only opens when max boost is reached as it is opened by the boost pressure in the inlet at a set pressure predetermined by an electronic solenoid, controlled by the ECU - or sometimes wastegate spring pressure. This is the line in which a bleed valve would be fitted to bleed boost pressure off keeping the wastegate shut, thus giving more boost pressure and power!! :D

The excess boost (when throttle is shut after accelleration) is directed thru a dump valve, which in circulation format puts the compressed air back into the turbo inlet before the compressor - or an atmospheric dump valve will emit the excess boost externally giving the infamous TTssssHH. The dump valve is always open when the throttle is shut as it works on vacuum and the wastegate works on positive pressure. The dump valve protects the turbo from sudden stall and allows it to carry on spinning between gear changes, so the lag/spool up time is reduced.

If you were to take you std filter/box off or if you have a sports filter fitted, you can hear the std dump valve recirculating - not as loud as an atmospheric DV, by can be heard from with the car!! :D
 

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Advocate said:
Hi everyone,

Have had my 52 plate ZT for just over a week now and think I may have a couple of problems.

Firstly, I've noticed what seems from inside the car to be a growling sound at around 2000 revs. Tonight whilst on my way to work I had the window open and rather than hearing the growl heard a distinct metallic rattle. I'm fairly sure that it disappears once the engine has heated up but it does have me a tad worried.

Secondly, very soon after starting the engine (about a minute if not less) I can hear what sounds like a fan starting up which continues until about 30 seconds after I've stopped the engine. The only thing I can think this is is the fan on the radiator. Should this be starting up so soon?

As the car still has a years manufacturers warranty left on it I'll probably get it back to the dealer to get them to investigate but am worried that I'm having problems so soon after buying the car>

Any advice would be appreciated.

Thanks in advance

Alistair
I had a similar problem - It was the catalytic converter. Needed replacing.
 

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Could also be the cat cover worked loose. Get a local garage to check it. I've had this happen on a Ford and a Peugeot and my mate burned it off for me and advised me not to park in long grass!
 

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Discussion Starter · #16 ·
Hmmm I think when I have time (that elusive creature) I'll book it in and get the cat checked out.

Dave: The more you reply to my posts the more you make me want a sports filter/induction kit....my missus ain't gonna be happy :)

Alistair
 
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