2.0 Duratec - Exhaust 'rattle'

[rotorwings]

My car (R300) has developed a 'rattle' from the (4:1 with Cat) exhaust at certain RPMs, and on 'throttle-off'.

I have checked all the obvious external possible causes (heat shield mounting on the cat., fasteners, joints, mounting etc.) and everything looks fine from that perspective.

I have now taken the silencer off and when I shake it from side to side (longitudinally) I can feel what I presume is the baffle moving back and forth.
However, the silencer does not make a 'rattle' sound when shaking it. I can just feel a dull, light, 'thud' when it hits the ends...

Is this probable loose baffle the cause of the rattle even though it is not making a 'rattling' sound when shaken by hand?
What are my options for fixing this? (NB - the silencer is riveted closed.)

thanks in advance..

[RedCat7]

I had similar sort of rattle which I thought was the exhaust but turned out to be the seat adjustment handle vibrating on the chassis and was cured using some sticky backed foam.

[Right Charlie]

Mine was caused by a slightly loose fit between the sections of the exhaust. Cured using high temp silicone.

[rotorwings]

Thanks for the tips. I'll have a look at these possibilities as well.
I took the cat off and it looks perfectly fine. No damage.

I've ordered some acousta-fil to repack the silencer. I understand this is just a matter of drilling out the rivets to get the can apart... Anyone done this?

Then I'll put everything back together and check other possible locations for rattles.

[DCL]

I've never repacked the one with rivets, but, as you say, they can be drilled out. You can extend the life of the wadding by wrapping stainless steel wire wool around the perforated tube first. The rattle may be the tube a little loose, or worn, in the end pipes/caps. Here's what a BTB looks like inside (with a CAT), but they are all similar in concept.

[rotorwings]

Thanks DCL. Hopefully everything comes apart nicely once I get the rivets out.
Apparently the Acousta-fil is really good stuff and should reduce the noise quite a lot. Feeling the current filling slide up and down the can when I shake it (I think there's at least 5 inches of empty space), I'm expecting a big change.

Any recommendation on what to use if it is the centre that is loose? Is there a particular bonding agent that I should use to fix it in place on re-assembly?

[DCL]

You could use an exhaust paste, but I would just expand or crush the inner tube to be a tighter fit. But I suspect when the new wadding is in, it will hold it all firmly in place.

[rotorwings]

So, I bought some a acousta-fill, and have now drilled out all the rivets, but the end of the silencer will just not budge!

Is it just a matter of more force?
Any tips?

Here is what it looks like:

[DCL]

I would put it back on the collector with a clamp and use that as some extra leverage to wiggle it off.

[rotorwings]

I have used 'vice grips' on the end with tie down straps and ratchet tensioners pulling on it (while tapping the joint with a rubber mallet) More tension than I could image getting by reconnecting it to the cat etc. and using that for assistance. Damn thing won't budge!

Do you think it's possible that the end/centre is not designed to come out (IE it's completely welded up)?

[DCL]

It could be that the inner tube and end caps are one welded assembly. You may need to drill out both ends to slide the outer casing off.

[rotorwings]

Hmm. The other end has nothing to drill.

It looks like this:

Does that say something about the construction?

[DCL]

OK, stand it with the inlet pipe end on a piece of wood on the floor. Lift it up and gently drop it (from a few cm) to see if the outer case moves. If it does, keep doing it until it slides off.

[anonymous-user]

DCL said:

OK, stand it with the inlet pipe end on a piece of wood on the floor. Lift it up and gently drop it (from a few cm) to see if the outer case moves. If it does, keep doing it until it slides off.

I acknowledge your greater experience, DCL, but the ends aren't going to go past the rolled in groove are they? It looks like they are there either to stop the ends being pushed in too far or to actually hold them in place.

[DCL]

REALIST123 said:

DCL said:

OK, stand it with the inlet pipe end on a piece of wood on the floor. Lift it up and gently drop it (from a few cm) to see if the outer case moves. If it does, keep doing it until it slides off.

I acknowledge your greater experience, DCL, but the ends aren't going to go past the rolled in groove are they? It looks like they are there either to stop the ends being pushed in too far or to actually hold them in place.

Looking at the photos again, I think you are right. My first take was that the ends were rolled in, but it does look like a groove. Just surprised it was only riveted at one end.

Edit: maybe the rivets are only there to aid assembly and the cap is welded to the pipe which is welded to the other cap? I'd start looking down the tube for clues as to how it is made.

Edited by DCL on Monday 28th December 19:34

[rotorwings]

Thanks for all the help and suggestions.

Yes, I don't see the outer sleave sliding off at all, because of the indents. It won't budge anyway...

Here's what it looks like up the inside. But it doesn't mean anything to me...

[DCL]

Not easy to see but there's some evidence that the perforated tube has been welded to the inlet pipe. That would then suggest the end cap has been welded to the pipe after it was fitted

Does anyone have any idea who manufactured it? Might be best to speak to them if you can.

[rotorwings]

Just an update to say how this one worked out:
- The whole internal pipe is welded solid all the way through (no joins)
- During manufacture the en-cap is held in place by the rivets, then welded.
- There is no way to get anything open without first cutting.

In the end, I managed to get everything apart and have created a re-packable silencer from the standard 'non-repackable' Caterham silencer. This was done by
- Cutting the end-cap right up close to the weld with a dremmel,
- Taking out all the filling and removing the outer sleeve.
- Then, I had someone cut the centre pipe and add an additional piece to allow refitting (just like with the re-packable silencers)
- Then rivets were added to the other end and the endcap was welded back on the centre.

Basically, 70€ to turn a normal Caterham silencer into a repackable one!

Here is what it looks like now:

[DCL]

Well done! I wonder why they made them like that. But that's a neat solution to the problem.

[one eyed mick]

Its big guess but they were made like that to part you from your money as many Caterham parts have been and probably still are !!!