Fiat Punto - rear knocking noise

poppy27_2

Hi

My back box on the exhaust fell off a month or so ago and so went to Kwik Fit to get a new one fitted (as well as the middle piece that was apparently rusted - whatever!) but ever since then it makes a knocking noise when I turn right (especially when going up slightly uphill) and more so when I have people in the back (when it will happen over bumps etc). It tends to be mainly when the car is first driven and then the sound eases off slightly. Any ideas what this could be? I did take it back to Kwik Fit and they said it was something to do with the heat plate (?) and that it was rusty and causing the problem but a bit dubious about that explanation!

Any ideas?

Richard53

Exhausts often run close to the underside of the car, and fitting them so that the normal movement doesn't contact the body is a bit of an art. If you can (and have the facilities), you could get underneath and try moving it about. It may be obvious where the pipe or silencer box is hitting the body. It may just need all the pipe connectors slackening off, relaxing the pipe run, and re-tightening.

If there is a heat shield and this has become loose through corrosion, then this could well be the problem. Again, a simple visual check would confirm this, if you don't mind getting down 'n' dirty. Repair or replace.

Because the exhaust is a fairly big lump of metal, and the underside of the car is big area, a small knock can sound like a major problem, but it may be quite a small issue, if you see what I mean.

poppy27_2

Thanks - just seems strange that it would be the heat shield when didn't have a problem before exhaust fell off - but perhaps coincidence. Think I may take back to kwik fit (another one) to see if they can fiddle about the exhaust a bit (tbh - when they fitted it the first time, the fitter took rather a long time and seemed to be having trouble with it and it seems lower than it was before) so I guess I'll try this route first - just hope it's nothing expensive!

Tilt

I have responded on the other thread.

I had this problem once with my HGT and it was down to the wrong rubber mounts being used. My money is on Kwik Fit using bog standard mounts when really genuine Fiat ones should be used. They are model specific.

Using the correct mounts solved my problem at least.

Richard53

The exhaust has a hell of a life down there, and corrosion is a fact of life. Often, things will hold together for a long time, but if one part is disturbed it can cause other parts to break up, fall off, and so on. That is quite common, and it's not (necessarily) Kwik-Fit trying it on.

Tilt

Richard53 wrote: »

The exhaust has a hell of a life down there, and corrosion is a fact of life. Often, things will hold together for a long time, but if one part is disturbed it can cause other parts to break up, fall off, and so on. That is quite common, and it's not (necessarily) Kwik-Fit trying it on.

I am speaking from actual experience. I had a back box replaced once where the garage that fitted it used standard exhaust rubber mountings. The tail section proved too heavy for these and caused the box to knock against the rear sub-frame. There were even occasions when the box became detached from the mounts causing it rest completely on the sub-frame! There were no issues with any other 'parts breaking up or fall off etc'.

It wasn't until genuine Fiat mounts specific to my HGT were fitted that the problem was cured.

And I did not suggest Kwik Fit were "trying it on".

Richard53

Tilt wrote: »

I am speaking from actual experience ...
And I did not suggest Kwik Fit were "trying it on".

My post was in response to poppy27's comment about the heat shield. She said she was dubious about Kwik-Fit's explanation.

I was not contradicting you at all, and I can't see why you would think I was.

Tilt

Richard53 wrote: »

My post was in response to poppy27's comment about the heat shield. She said she was dubious about Kwik-Fit's explanation.

I was not contradicting you at all, and I can't see why you would think I was.

Looking at the timings of the posts I realise that now.

My apologies.

Richard53

No problem. I thought it might be something like that