totally OEM exhuast rattle - low speeds - help

[Chris_R27]

Picked up my 197 Nimbus F1 on Saturday. Drove 200 miles home no problem, but at low speed circa 2500 rpm, there is a real metalic hollow rattle from under the handbreak.

Having owned kit cars and clios (V6 and 1.2's as well as plenty of 182 and 172 exprience) I am confident the area in question is the exhaust or a heat shield working loose.

I see a lot of people cut out their centre sections, is this wy or is it just for volume and over run pops?

if anyone can tell me what to look out for or previosu encounters that would be great.

Its not the boot lock I am sure as you cna hear it when staionary and revving, although not as badly and when moving

 

[GrumpyTwig]

People just cut it out for the noise.


Could be the hangers for the exhaust are knackered, even new they've been known to rattle against the shield when really thrashing it, mine did and probably still does.

You'd need to get under the car to check it though as it might be obvious looking at it.

 

[deadmau5]

I'd say it most likely sounds like the centre silencer.

 

[Chris_R27]

What about the cente silencer? The fact it is loose or knackered inside? I have read about cats rattling, but that would be further towards the front of the car

I'd say it most likely sounds like the centre silencer.

 

[deadmau5]

Probably the baffles. The baffles in my back box went a few weeks back. They're made of mild steel so won't last forever. Also, my baffles resonated loudly travelling at 2500-3000rpm but less so when the car was stationary and revving.

 

[Chris_R27]

hmm, but it was fine at say 4000 rpm on the motorway

 

[deadmau5]

So was mine, it was only noticable at 2500-3000rpm and 5000-redline. It was particularly worse under full throttle. I have since replaced my exhaust system and the problem has gone

 

[Chris_R27]

So to confirm, your issue was the internal baffle on the centre section of the exhaust?

I think you know the previous owner, Dave_R27 (accoridng to the R27 register) it appears to be a mint example as far as condition

 

[deadmau5]

No mine was the back box baffles. I chopped my centre silencer out a while ago (it wasn't faulty, I just wanted more noise).

I don't recognise the name but I'll look on the thread.

 

[Chris_R27]

Just been round the block, not a squeak, pull onto the drive and it's there again. Must be when it warms up perhaps?

 

[deadmau5]

Weird. The best thing might be to take it to a garage, get it on the ramp and rev it. Probably not the safest though

 

[r_vlad]

You should check the bracket between the main catalytic converter and the small one. Mine got loose causing the exhaust to resonate between 2500 and 3000 rpm. After I tightened the screw everything went back to normal.

 

[Chris_R27]

Cheers vlad. Got to get under it and check it out.

 

[Chris_R27]

Was a very slight crack in the weld from the pipe linking 2ndry cat to mid mix.

Got a local exhaust fabricator to weld round the whole join on both sides of the mid box.

Annoying rattle/buzz has now gone for £20. Made me want a bit less baffling now as the minor leak gave a deeper note lol.

 

[Yiannis197]

Just seen this thread. I came across exactly the same problem when I was on my trip in Europe. When it was cold there were no rattles at all however when it'd get warmed up the rattling would appear. I had it checked in a garage in Germany and they found a leak from both sides of the already knackered silencer. Time for a stainless steel I guess.

 

[Chris_R27]

Yeah mine was only leaking one side (cat) when hot and at low speed. Motorway cruising etc no issues.

Stephiscoped (spelling) the boxes and nothing was loose or rotting so got away with new welds around both seams.

 

[Dave_R27]

Probably a bit late but only just seen this thread.

Yes the problem is the centre silencer confirmed by warrington Renault. £350 fix from dealers, or just replace the centre box with a straight through pipe (£40) but it will pop and be very roughty.

The problem is only apparent at low speed when engine is warm.

If I was you I would just buy a full K-Tec system I considered this, but ended up selling the car. I have sent a PM with full details.

The car is in mint condition, enjoy!