mysterious metallic "clonc"?

mysterious metallic "clonc"?

Author
Discussion

zeppo

Original Poster:

250 posts

189 months

Friday 11th April 2014
quotequote all
Hi all!
I love the pops and the bangs from my car, but recently it starts with an metallic clonc. It sounds a little bit like knocking on a spring and it seems (but I'm not sure) to come from the mid section of the car.

I went to a garage twice, but we couldn't find the problem.
We checked:
- all silent bumpers
- all dampers
- steering
- all prop shafts
- engine mounts
- diff/gearbox bumpers
- wheel bearings

Any ideas?

Next step will be demounting the prop shaft and then total demount of all wheel suspensions...

cheers Josef

peteA

2,679 posts

233 months

Friday 11th April 2014
quotequote all
I think more info might be required...

When you say 'starts' - do you when the engine starts? ie the clunk happens the car is stationary and you start the engine?

or is it on the move?

is it just when the engine is cold or also when its hot?

...a bit more detail might help the better experts than me narrow things down!

twinreal

300 posts

154 months

monty quick

230 posts

235 months

Friday 11th April 2014
quotequote all
Not sure if this is the same but I have recently noticed that when my T350 is hot I get a metalic clonk (really only noticeable at slow speeds). It only happens when the car is moving so it is not engine. Doesn't seem to be dependant on load so not engine mounts. I can only describe the noise as if it was something standing vertically and rocking side to side with movement of the car and hitting against adjacent surfaces.
I can't find anything loose and, as I said it only happens when the car is hot? It is driving me crazy!

zeppo

Original Poster:

250 posts

189 months

Friday 11th April 2014
quotequote all
Sorry, I forgot to mention that...

It's not coming from the engine, the gearbox or clutch.

It appears very irregular.

I think, it's more frequent, when the car is slow and it's in a "body roll movement" like a curve or a barrier.

zeppo

Original Poster:

250 posts

189 months

Friday 11th April 2014
quotequote all
@twin
hmmm, don't think so - if it's the tank, the noise will always come from behind...

peteA

2,679 posts

233 months

Friday 11th April 2014
quotequote all
Something to do with the Cats maybe - how old are they? Could they be breaking down and what's left is rattling around?

zeppo

Original Poster:

250 posts

189 months

Friday 11th April 2014
quotequote all
1st registration: 23.1.2006 and 30k miles on the clock

I don't think, it's a broken CAT, cause I can hear the noise only when moving.

Milky400

1,960 posts

177 months

Friday 11th April 2014
quotequote all
my two suggestions and speaking from experience, would be full tank and exhaust/cats. Had both issues in a previous car, tank is a low thud and you can usally feel it. The exhaust was a metallic rattle

zeppo

Original Poster:

250 posts

189 months

Friday 11th April 2014
quotequote all
I have a rattling exhaust - exhaust is totally fixed, but the diffusor is shaking at 2-3000RPM and hits the exhaust...

But I will check the fuel tank this weekend...

chris watton

22,477 posts

259 months

Friday 11th April 2014
quotequote all
zeppo said:
I have a rattling exhaust - exhaust is totally fixed, but the diffusor is shaking at 2-3000RPM and hits the exhaust...

But I will check the fuel tank this weekend...
I noticed that, on my diffusor there were burn marks from where the back box 'rested' on it when hot (the sports cans have eliminated this problem). I wonder if it's worth adding some after market heat shield to the top of the diffuser, which would be hidden due to the number plate/rear exhaust shield - this should also minimise rattling when the exhaust heats up, shouldn't it?

peteA

2,679 posts

233 months

Friday 11th April 2014
quotequote all
chris watton said:
I noticed that, on my diffusor there were burn marks from where the back box 'rested' on it when hot (the sports cans have eliminated this problem). I wonder if it's worth adding some after market heat shield to the top of the diffuser, which would be hidden due to the number plate/rear exhaust shield - this should also minimise rattling when the exhaust heats up, shouldn't it?
Chris...I must be a few steps ahead of you on the mods front! My car suffered from a crispy rear diffuser too so I applied some heat reflective material in the manner you described (I think!)...all is well so far...




chris watton

22,477 posts

259 months

Friday 11th April 2014
quotequote all
peteA said:
Chris...I must be a few steps ahead of you on the mods front! My car suffered from a crispy rear diffuser too so I applied some heat reflective material in the manner you described (I think!)...all is well so far...



Wow! That's exactly what I meant!

Your car looks like my colour on those shots!