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rover_400_95_99
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Discussion Starter · #1 ·
Had a new exhaust fitted last summer (everything except from the Cat. Converter) and never had any trouble but just recently as I hit high revs when accelerating or when coming down in speed in 5th gear (around 52mph) I get this awful rattling sound from the exhaust from, I am guessing, around the CAT area underneath the centre console.
Driving me mad!! I am planning to take it back to the garage where it was fitted but is it likely that it's the CAT that's gone? Somone once told me that if they rattle (like pebbles in a tin can) then they are shot??!

Any ideas?

Cheers

Jon
 

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it's in your cat, needs to be removed and checked.
it did that to me too when I replaced my exhaust and did a decat.
 

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I recently had a similar thing with my zs.

If the exhausts are similar then the problem with mine was...

There's a flat plate with the sides bent down (or something like that) welded onto the top of the exhaust kinda just underneath the centre console, With me it had been spot welded on on the four corners and two of them had come loose.
Up on ramps, 10 minutes, my mate welded it back on and bob was my mother's brother.
 

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rover_400_95_99
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Discussion Starter · #4 ·
Cat

Booked it in for new CAT anyway as the emmisions were a bit high last MOT so it probably needs doing. Will inspect that plate though if I can.

Thanks

Jon
 

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As the_chief says it's more than likely a loose heatsheild around that cat that vibrates at the exhausts resonant frequency. Usually there's clearence to bend the heatshield a little to avoid it fouling on the chassis.
 

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As said above, most likely to be a loose heat shield rattling at certain frequencies of engine rpm.

Heat shield mountings can just rot through, same thing happened to a mate's Mum's elderly Nissan Micra. he got underneath it and just pulled the remains off the exhaust - it doesn't rattle now.:spanner:
 

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it's not always the heatshield, the cat can do the same rattle when it's got something loose inside.
 

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it's not always the heatshield, the cat can do the same rattle when it's got something loose inside.

As I said most likley heat shield - of course it could be the cat breaking up if it's a really old car.:eyes: Hell, a heat shield is a lot cheaper than a new cat anyway.
 

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As I said most likley heat shield - of course it could be the cat breaking up if it's a really old car.:eyes: Hell, a heat shield is a lot cheaper than a new cat anyway.
won't do him any good if he destroys his heat shield and finds out the rattle is still there.
best way to know is to go under the car when it hasn't run for a while and just hit the cat area to hear where the rattle comes from.
 

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won't do him any good if he destroys his heat shield and finds out the rattle is still there.
best way to know is to go under the car when it hasn't run for a while and just hit the cat area to hear where the rattle comes from.
You don't give up do you?
Are you ever wrong?

Must be nice to always be right all the time. :wtf:
 

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rover_400_95_99
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Discussion Starter · #13 ·
Rattle

It was the heatshield in the end!! It was (supposed) to be held on by 4 bolts but as they were steel bolts through ally plate (!) it just fell to pieces.
He cut it off in the end and I will do without it I guess. Most new cats I have seen don't even have a heat shield!!
Problem solved and saved myself £80+

Cheers

Jon
 

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It was the heatshield in the end!! It was (supposed) to be held on by 4 bolts but as they were steel bolts through ally plate (!) it just fell to pieces.
He cut it off in the end and I will do without it I guess. Most new cats I have seen don't even have a heat shield!!
Problem solved and saved myself £80+

Cheers

Jon
Glad you got it sorted mate!
 

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More often, in my experience, it is the heatshield.
so it seems, but it's always good to let people know everything that can cause a problem and not just focus on one.
all I said is that in my case, it wasn't the heatshield that caused the rattle, I don't see why some guy in a yellow car would bark at me for that. :)
 
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