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[Brynjaminjones]

Afternoon 'Dastards!


I fired the XJ up yesterday, and noticed that the exhaust is now making a horrible buzzing/rattling sound at low revs, which is enough to drive me insane!
A quick trip to the mechanic today decided that it's something inside the silencer itself. I only fitted the exhaust a few months ago, but already it looks completely battered - I must have damaged it at Breakout. 


Anyway, because it's so battered I doubt it has any warranty - is there anyway to stop it's innards from rattling at all? I don't mind if that means the exhaust gets louder or whatever, I just want to stop the rattling!

[big g]

If the baffles have broke lose you'll need to crank up the volume on the Infinity.

There be no fix.

[Brynjaminjones]

That's been the solution so far, but people look at me like my Jeep's falling apart around town now!!
Looks like I'll have to put up or replace then 
Or maybe I could replace it with a piece of straight pipe 

[big g]

Bomb the MOFO.

[Hillbilly]

You sure it ain't the cat. Broken ceramics sound a lot like you are describing. I know from experience. 

[bigjeepzj]

my cat rattles has been like it or years with no probs

[wildwood]

As above .....bet it's the cat...

Get underneath with yer steel toed boot and give the cat a kick......rattle cat mean the ceramics are rogered but will still pass the mot....... Cheap from Lighties don't buy a factory part cos £££££
hey don't like a cold dunking in water then hot then. Cold etc........

so nothing to worry about............

[Hillbilly]

Got to say that I ignored my cat rattle and it passed two MOT's. Work transferred me to Stockport which must be up there as speed bump city and even Iron Maiden couldn't drown out the clunk on every bump. Had to succumb and replace it on the XJ and ZJ.  Wildwood has it right do not go main dealer if you want to replace it.

[JamesH]

If it is the cat try cats direct .co.uk or similar - google it. About £65 last time for mine

[Jeepjedi]

You sure it ain't the cat. Broken ceramics sound a lot like you are describing. I know from experience. 

My thoughts to, Guru point please 

[Brynjaminjones]

Blimey, lost the interweb for a day and wasn't expecting all these replies!


I've had a good listen, and it really does sound like it's coming from the silencer, and Mr Mechanic said the same. I've heard cat rattles before, but this doesn't sound the same. This is like a harsh buzzing that comes at certain revs, and isn't affected by bumps.


I still haven't ruled the cat out though, but the fact that my exhaust looks so battered seems to fit. I'll go and look again later on, and give it a good kick!   I'll also get it up on a ramp in the week for a poke about.


Big G, I take it you mean a Cherrybomb??   I'm half seeing this as an excuse to get something with a bit of a growl, when finances allow! 

[Brynjaminjones]

I've been and taken a video, and now I'm near certain that it's coming from the back of the silencer.


Here ya go:



I'm going to email the place I got the exhaust from to see if they'll do anything, as having seen a picture of it when it was new I'm not sure it is actually as battered as we thought.

[Dave69]

get rid of the standard silencer as it will always ground out. fit a cherry bomb silencer same bore as the exhaust, 2 foot long. that will the sit level with the chassis rails and not ground out. sound is nice and not too intrusive

[eastryjeep]

If you have access to a welder read on or else please disregard this cheapskes fix!
Let it get cold then start the engine and feel along the silencer, you should see where the spotwelds are that used to hold the baffles, somewhere in line with some of these welds you should feel the buzzing going on inside. When youve identified the loose baffle put a G clamp across it and try to pinch the silencer slightly, the noise should stop or change pitch if more than one has gone, now mark it! Keep going until all the rattly points have been identified.
At this point ask yourself a few questions:
1. Is it so stuffed I need a new one,
2. Can I be arsed to fix it,
3. Do I want a hollow box or not,
If its well shagged or you cant be bothered then its time to find a new/another silencer.
If you want to fix it or a hollow box remove it from the vehicle and read on:
Hollow box first. Without cutting into the outlet pipe grind away the seam weld or rolled joint around the circumerence of the silencer and remove the end cover and outlet pipe. Depending on construction you may have to shorten the outer casing a bit and cut through the outlet pipe on the inside of the silencer. Once you are into the guts of the box you can either ditch the lot or go a bit more carefully, find the loose baffle, tack it back in place, and reassemble in a gas tight manner. The finished article should be no more than about 1/2" shorter than when you started.
OR.
If you dont want to carve into the box as above, drill out the identified loose spot welds, clamp the box against the baffle and plug weld it in place, working your way around the box you should be able to secure it as well as it ever was. The belt and braces version of this fix is to drill through the outer box and baffle flange and insert a blind steel rivet to hold everything together then weld over the rivets to ensure they are gas tight.
I know a replacment is the easiest but if you are as strapped for cash as me it's a way forward and it keeps me out of mischief indoors!

[wildwood]

I have a round silencer that used to be on the YJ before I ran.  The exhaust the other side.....Tis a not too quiet but not illegal noisy one and is straight thro......cos you can see. Straight thro......

 Will take pics tomorrow........usual rules.......postage to cover myexpenses and if any good a few groates to Help for Heroes, if. No good throw it back at me at CF......

[Brynjaminjones]

Cheers for all the help guys!


I actually got the exhaust replaced for free on warranty, as it didn't look like it was dented - more like it was deformed.


After driving with no exhaust for a couple of days  though, I think I'd like something a little beefier sounding. Jez, I'm in France until Friday but will PM you when I get back!

[wildwood]

Here Ya go 14" length and 5" diameter..... bolt on if you want one end and as you see it on the other end
51mm and 55 mm diameter respectively.... inlet outlet......