Astra mk4 Exhaust

Hi,

I had problems with my exhaust system which I posted here a while back. My
local Vauxhall dealership replaced the centre box even though the noise is
coming near the front. I had to pay for this even though the car is under
warranty as they cant hear anything wrong with it.

When I bought the car about 8 months back it was quiet as a mouse, now the
engine noise seems 10 times louder especially if the the throttle is down
and if your doing 60mph for sometime its really annoying. However it doesn't
make this noise all the time. Cant put my finger on it neither can the
garage.

Its done 60k and is a V plate so what parts are near the front of the car
off the manifold ? Is it manifold then pipe to cat then pipe to centre box?
Would the cat be dead? Im guessing they're really expensive from a Vauxhall
dealership? Can only get them to do it otherwise I break the warranty.

I figure im going to have to keep paying for parts until I can no longer
hear it making a noise like a tank.

Cheers

Matt

 

When the noise is present, is there a noticeable lack of power?
Any misfiring?
The fact that it's louder with open throttle, could mean there is an
induction fault.
When were the oil and filter last changed, and what grade oil was used?

 

Hi,

I dont notice any power loss although it seems that pickup in 2nd gear is
slower than what it used to be.

Ive got no engine management lights on and the oil/filter was changed in
January when it was serviced. Not sure on what oil was used.

Cheers

Matt

 

If the oil grade is too thick, it could cause problems with the hydraulic
lifters, therefore the valves wouldn't close properly; the result would be
blow back through the intake system,causing a lot of noise and lack of
power. It might be worth changing the oil and filter, just to be on the safe
side.
Other than this, possibly the cat itself is collapsing, or one of the
baffles.

 

Hi,

Yeah I was thinking the cat was dead. The oil that they put in it says on
the service sheet was Z4 BULK Castrol Perform if that means anything to you?

How much is a new cat these days from Vauxhall?

Cheers

Matt

 

A bit late but I have only just joined the newsgroup.
Is the Astra Mk4 the same as the Astra-G? If so then the following may be of
help. It is odd enough to fit in with your symptoms and a cheaper first shot
than the cat.

From a pukka VX workshop manual:

Complaint:
Noises or vibration.
During change of engine speed a vibration noise could be produced by the
non-return valve of the vacuum pipe to brake booster (servo). Note that
this noise is often misinterpreted as exhaust, timing belt or tension pulley
noise. For a clear diagnosis you should remove the vacuum pipe from the
brake booster and block it.

Cause:
Resonance in vacuum pipe - non-return valve

Remedy:
In case of complaint replace NRV assembly

Hope the above is of help. If nothing else it illustrates how a fault can
be far removed from where you would think it would be.

Vin