my quest for a quiet exhaust pipe!

right, been having probs with booming 110 300tdi. gonna try changing some exhaust parts to quieten it down as at 50mph its over powering!!!

currently has a solid decat- OME center silencer- unknown make rear silencer.
at tick over it sounds nice, veeeeery deep bass sound.
now after a bit of research, i see people saying rear silencer isn't a silencer! its a resonator!!!
so more research shows they are different inside and do different things to the gasses.
my question is:
can both wear out? im pretty sure the baffles in a silencer can but what about a resonator?
should i change rear resonator or mid silencer?
dont want to change resonator if they dont wear out!!
cheers

Nothing in the exhaust "wears out" it cant, theres no moving parts, what the do, however is get full of gunk, and rust out from corrosive gases.

First off id check all the rubbers the sound absorbing material in the fid box can get full off soot, but im not sure itd make much difference tbh.

is it a van back you have, if so, spending money on lining it out will have far more effect on the booming noice at speed than playing with the exhaust, ive got a 300tdi 110 CSW and the engine noise is far more noticable than the exhaust on a run, and ive removed the mid box and cat alltogether,

timtheenchanteruk said:

Nothing in the exhaust "wears out" it cant, theres no moving parts, what the do, however is get full of gunk, and rust out from corrosive gases.

First off id check all the rubbers the sound absorbing material in the fid box can get full off soot, but im not sure itd make much difference tbh.

is it a van back you have, if so, spending money on lining it out will have far more effect on the booming noice at speed than playing with the exhaust, ive got a 300tdi 110 CSW and the engine noise is far more noticable than the exhaust on a run, and ive removed the mid box and cat alltogether,

Click to expand...

yea its a van back.
something is not right then, when i say mine booms it REALLY booms, at 55mph cant here engine at all, or wind noise!! or stereo! its really loud!

its definitely not blowing either been right round it !

the full of soot thing is interesting, as been running with dodgy stem seals for ages and it kicked out a lot of smoke! also when recently changing head the exhaust ports were caked in oil!!

new tailpipe and midpipe didnt cure it!!:Cry:

That is really weird. I can't think of anything that would cause that

Edit: could it be the manifold? I know the gasket on mine was split in multiple places when I did the head.

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had new gaskets and studs when new head went on.
looks like i will be chucking money at it til i cure it! next thing to try might be replacement down pipe!
wonder if its possible for manifold to blow past the "push in parts" there is no sign of soot but i suppose its worth checking

Are you sure it's not intake noise rather than exhaust noise. Intake can make a lot of noise when running K&N style filters and no boxes. But then I only really have experience with V8s not diesel.

do you have a snorkel? mine got noticable noisier when I added the snork with the intake being right by yer head

standard air box and intake no snorkel. I originally though it was the intake, i have a thread running about that too but that was more to do with a popping noise i was getting and was cured when i changed head!
ive ran it with air box lid off, booming no change but noticeably louder air sucking noise.
ran it with filter removed, booming the same only very loud sucking air noises!
im gonna .
im gonna go and investigate a bit further see if i can get a vid.

When did it start? Something must have been changed to cause it?

james6546 said:

When did it start? Something must have been changed to cause it?

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just noticed it gradually over last 4 month!

right took the bonnet off and done some filming.
it only booms under load, any gear its rev dependent.
so to eliminate wind noise as best as pos i stuck it in low range 2nd gear.
from outside you cant really hear the booming! but inside you def can!
defender 300 tdi booming - YouTube

mine used to be quite bad until I put down some 6mm rubber in the load bay floor, that stopped a lot of the noise, than last month my mid box rotted out so I changed it for the S/S straight pipe, the difference in noise level was mental, as in their was none!
Mines is Ex MOD and has no egr, the mid silencer we took off was a straight pipe all the way through but had a perforated part in the middle. presumably to let the gasses into the silencer,
we put the reduction in noise down to removing the restriction right below my empty passenger seat box,

g-mack said:

right took the bonnet off and done some filming.
it only booms under load, any gear its rev dependent.
so to eliminate wind noise as best as pos i stuck it in low range 2nd gear.
from outside you cant really hear the booming! but inside you def can!
defender 300 tdi booming - YouTube

Click to expand...

That sounds more like body panels resonating?
Has it got a headlining?

yea its got head lining, also recently sound deadned the front cab with no effect on the boom. Im starting to wonder if its maybe an engine mount. from the vid you can hear its not an audible noise from engine bay. so must be something resonating causing such a low frequency.

Why is the air filter so loose? Can it touch the bodywork?

boguing said:

Why is the air filter so loose? Can it touch the bodywork?

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don't know! it definitely has rubbers on as i replaced 2!actually when studying the engine at tick over on the vid the whole thing moves quite a bit! think im gonna look at the mounts!!

try getting somone in the back to touch one, or both the side panels, and see if that makes a difference, it does sound like an interior resonance, a bolt or somthing working loose on a panel can have quite a dramatic chance of resonant frequencies.

are the van sides and roof still securly bonded to the frame? is there a headlining in the back, and if so is it secure?