What would cause a Petrol car to start sounding like a Diesel?

chickendipperbabe

The car in question is a 2011 Vauxhall Agila 1.0 - only 11,000 miles on it.

Any pointers would be appreciated, asking on behalf of my sister in law. As the title suggests, she has a car that sounds as rough as anything at mid-high revs. Apparently its always sounded a little rough, this was queried when the car was bought (new) but she was told that it was because it was a three cylinder engine and they're all like that. Within the past few weeks the noise/rough sound has become more noticeable. Its not there all of the time, only when the revs are at or above 2500. The sound is identical to that of a small Diesel engine being thrashed, that rattle clattering sound. The car starts and idles normally. Nothing is loose under bonnet, fluids are all fine and the oil is perfect. It drives fine too apart from the noise with no weird vibrations that I would associate with the noise, I did notice the car seemed to lack power.

I know its a tall order with my vague description but has anyone had a similar issue?

agrinnall

It's probably not this as it's really a different symptom, but...

https://en.wikipedia.org/wiki/Dieseling

bigjl

Has the car been serviced every year despite the low mileage?

Don't know an awful lot about that car or engine but it could be worn tappets or possibly camchain if it has one.

You could try a search of the Vauxhall Owners forums as to is possible the engine is fitted to the Corsa and the issue may be more common due to numbers sold.

Marktheshark

Sounds like a coil pack failure

FreddieFrugal

chickendipperbabe wrote: »

I did notice the car seemed to lack power.

Agila 1 litre, I think lacking power is standard fit.

Norman_Castle

Has it become noisier recently due to the car windows being open?.

https://www.youtube.com/watch?v=Aqmt-Tnfybw

zaax

Could 100 and one things, you could be making it worse by not getting it fixed. Is it still under warranty?

Strider590

If the original noise really was "normal", then the first thing i'd be checking was for a loose heat shield on or around the exhaust, as this will make a right racket as RPM rises.

chickendipperbabe

Thanks for all the replies.

The car has been serviced every year by a main dealer. I did think tappets but the sound is nothing like it. It has been taken to a reputable garage and they suggested it might be a timing chain issue but it was only a guess.

I will investigate the coil pack suggestion, though there is no misfire or judder - the car drives normally apart from the sound and also no warning lights on the dash.

The car is just outside its warranty. The sound was investigated soon after the car was delivered in 2011, its always been there at a low-ish level and the Garage suggested it was due to the engine being a three cylinder job as no fault was found, the sound is more audible with the windows down actually but its 100% coming from within the engine itself.

Again thanks for all the replies, will also post this on the Vauxhall owners forum as suggested above.

Marktheshark

This could be the dreaded VX con rod pin failure then, is it like a cam ticking noise but deeper seated ?

chickendipperbabe

Strider590 wrote: »

If the original noise really was "normal", then the first thing i'd be checking was for a loose heat shield on or around the exhaust, as this will make a right racket as RPM rises.

The heat shield or part of it is in the boot. The front section (both halves) fell off long ago. Its definitely not a heat shield sound.