Rattling exhuast question

Fox · Unread post by **Fox** » 25 Jun 2003, 21:57

Hi there,
As posted previously my exhuast rattles at idle. The rattling stops when I put my foot on the tailpipe. Took it to a garage for a quote today, they put it up on a ramp and found the problem as being where the exhuast connects to the engine - I think he called it a manifold. Anyway, he quoted £40 to fix it. Before I go ahead and say yes, does this sound right?
Thanks.

mbunting · Unread post by **mbunting** » 25 Jun 2003, 23:05

You could stick it on a ramp and fix it yourself, along with other checks, in less than an hour !

JohnD · Unread post by **JohnD** » 25 Jun 2003, 23:19

If the rattle stops when you put your foot on the tailpipe, perhaps the silencer box is touching the underside of the car. If you've had a replacement rear box fitted, it could be that the support brackets have a slightly different shape to the original box. If so - a bit of bending of the brackets will solve the problem.

Homer · Unread post by **Homer** » 25 Jun 2003, 23:49

If the rattle stops when you put your foot on the tailpipe I doubt the problem is right down the other end. Like JohnD says it is probably just touching something.
That doesn't mean there isn't a problem at the manifold end but I would guess it not mounted right at the back.

nick · Unread post by **nick** » 26 Jun 2003, 00:09

...or the baffles in the back box have started to disintegrate and are rattling about. I've known this problem on two BX's, but not a Xantia before.

Fox · Unread post by **Fox** » 26 Jun 2003, 00:38

Hmmm. Confused now, wish I knew more about this sort of stuff [:)]
When it was up on the lift, the guy showed me what he meant. He put his hand on the pipe just after it came out from under the engine, and the rattling stopped - just the same as it does when I push my foot up hard on the tailpipe.
Has the guy mis-diagnosed it? Tempted to pay him 40 quid and get him to fix it anyway, if he mis-diagnosed it its his problem, surely? [:)]

hswift · Unread post by **hswift** » 26 Jun 2003, 02:03

If there's a catalytic converter fitted - between the downpipe and the first box - give it a smack with your fist. If it rattles, that could be the cause. Just had the cat. break down on my Xantia and it was rattling like crazy.

mbunting · Unread post by **mbunting** » 26 Jun 2003, 03:25

On the AX ( which is still out of action ), there is a metal 'mesh' guard under the cat, and this rattles like hell given the correct rpm.
It could be something as simple as the spring loaded bolts not being tight enough ( or the connections mis-aligned ) between the middle section and the elbow. These are 10mm heads, and you're better off with a long extension and socket for the nit, and use a ring spanner to hold the top head.
I know this because I've done the damned thing loads of times in the last few weeks !

sooty · Unread post by **sooty** » 26 Jun 2003, 03:39

Or one of these spring loaded bolts might be missing ie: broken ??
Sooty

debutant · Unread post by **debutant** » 27 Jun 2003, 04:12

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by JohnD</i>

If the rattle stops when you put your foot on the tailpipe, perhaps the silencer box is touching the underside of the car. If you've had a replacement rear box fitted, it could be that the support brackets have a slightly different shape to the original box. If so - a bit of bending of the brackets will solve the problem.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
I HAD the same problem! The Cit garage told me it was the rear box knocking the chassis (the box and cat were replaced a few months ago .... very expensive!). He also told me it couldn't be fixed. I tried your suggestion today and grapped the rear box and pulled it a bit several times (to reshape the rubber brackets). Since then, the car drives clear as it should be. Probably have to do it again some time soon, but at least I do know where the horrible knocking comes from.
Cheers m8!

Fox · Unread post by **Fox** » 27 Jun 2003, 04:28

Had a listen in the engine bay today - you can definetly hear the rattle coming from around the engine. Ah well, I'll find out tommorrow when I part with my £40. I asked them to 'fix the rattle' and they said £40, no problem if they fix the wrong thing hehe [:)]

Fox · Unread post by **Fox** » 28 Jun 2003, 13:17

Well, they've done the work and the rattle has now completely gone, which is nice.
However, at idle now I have an odd sensation, like a booming noise in my ears if that makes any sense at all. Increasing the revs to 1000rpm makes it go away, but obviously increases the engine speed.
From outside, the car sounds normal.

jeremy · Unread post by **jeremy** » 28 Jun 2003, 15:38

Could be that the pipe is strained somewhere and loading the mounts unequally - or that the front mounting is the spring bolt type and the bolts have been done up too tight and the springs totally compressed.
Probably worth a look underneath. For what its worth on my BX the exhaust tends to move the rubber mounts around and they get near the ends of the holes after a while.
Jeremy

Dave Burns · Unread post by **Dave Burns** » 28 Jun 2003, 16:01

Its not possible to over tighten the (original) bolts and squash the springs as the bolts have shoulders, the nut is screwed down until it and the cup washer stops against the shoulder.
Note: make sure these are assembled with the insulating washer between the spring and the exhaust pipe flange, otherwise the spring recieves too much heat and goes weak.
Dave

jeremy · Unread post by **jeremy** » 28 Jun 2003, 16:40

Thanks Dave. you can tell I've never had to break that joint! - assuming the correct bolts were used.
jeremy