Mazda 323 Diesel - Turbo - possible problem?

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Sun 8 Apr 2012 23:35
Mazda 323 Diesel - Turbo - possible problem? - jazzyman

Any experts on turbos?

I have an engine noise that appears to be coming around the turbocharger area, noise comes when accelarating hard around 2500 rpm under load with a hot engine.

Checking out the wastegate on the turbo I cannot figure out how the wastegate operates? I have a turbo boost guage which reads 14 psi on full boost, which is average and ok for this model.

However checking the workshop manual the wastegate actuator testing procedure is to attach a pressure line and the wastegate actuator starts to opens at 35-37 psi.

So with a 14 psi boost how does the wastegate open? Car seems to have plenty of power so the wastegate must be opening? I also disconected the air feed tube to the actuator valve ( blanked off tube) and there was no difference in the car's running or performance.

Please could someone inform me if there is a problem or perhaps this is the normal action of a turbo?

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Mon 9 Apr 2012 14:17
Mazda 323 Diesel - Turbo - possible problem? - Peter.N.

I am not familier with this particular engine but if that wastegate operating pressur is coming from the inlet manifold its way to high, I think there must be an error there. What sort of noise are you getting?

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Mon 9 Apr 2012 18:37
Mazda 323 Diesel - Turbo - possible problem? - jazzyman
The boost pressure is being measured from the pressure hose off the actuator (diesel motor).

Job to describe the noise..it's more of a chirpy type knock bit like a noisy injector but much quieter and it's coming from the turbo area. There's no noise until the engine warms up and is worse if the car is parked for a short while when the engine is hot. No noise when the car is stationary only when accelerating hard.

Extract from the manual and it does seem to be a high pressure to actuate the wastegate..that why it does not make sense..

[img]img856.imageshack.us/img856/8894/maz.jpg[/img]
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Mon 9 Apr 2012 18:42
Mazda 323 Diesel - Turbo - possible problem? - galileo

Car seems to have plenty of power so the wastegate must be opening?

The wastegate opens to limit boost and power, not increase it. The workshop manual figure is worth checking with a dealer, it seems a bit high.

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Mon 9 Apr 2012 18:49
Mazda 323 Diesel - Turbo - possible problem? - galileo

Just seen the link, this does say "absolute pressure" , which may mean that as ambient atmospheric pressure is on the other side of the wastegate diaphragm the boost at which it opens is 32 - 37 psi minus ambient of 14.7 psi i.e 17.3 - 22.3 psi.

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