Mysterious Rattle????

[rajinder_1]

Hi Guys,
I have posted this before but still not found the cause, i can hear a rattle sound coming from the exhaust, i think its from the exhaust anyway. It is there sometimes and not others the rattle that is the exhaust is always there....
But it only sounds when the car is in gear, if in park its smooth revs, as soon as i put in drive the rattle starts, i have however heard it when i start the car in the morning while in park, its everso anoying and have been told its the cats, but if it were the cats wouldnt the rattle happen all the time?

I am boggled to what it is, it sounds like it comes from the front drivers side inlet manifold or around there when its parked up firt thing in the mornings...

any ideas car is SL320 2001. If its cats i better save my pennies MB cats are £1300 for a pair.... i dare not risk aftermarkets after a long saga with GSF about ones i had from them....

Raj

 

[Parrot of Doom]

Could be the exhaust heatshield, or the cats. Check the former first, around the manifold, and underneath the car. They do come loose easily.

Perhaps as you engage gear, the idle speed drops slightly, and the rattle begins?

If its the cats, well personally mate at that price I would cut them out, replace them with straight pipes, and every MOT time put them back in for the day.

 

[rajinder_1]

its not the heatsheilds have checked it many times to see if it is anything other than the cats....

nothing is touching anywhere as far as i can see... but the cats stilll look like the main culprit, just dont understand why its not happening constantly

they are bloody expensive but i dont think that you can compensate with cats ive tried and had my finger burned!!!!

 

[marcos]

its not the heatsheilds have checked it many times to see if it is anything other than the cats....

nothing is touching anywhere as far as i can see... but the cats stilll look like the main culprit, just dont understand why its not happening constantly

they are bloody expensive but i dont think that you can compensate with cats ive tried and had my finger burned!!!!

Why

Did the cat have matches

 

[rajinder_1]

yeah matches that lit fire to my pockets.... lol

 

[Parrot of Doom]

its not the heatsheilds have checked it many times to see if it is anything other than the cats....

nothing is touching anywhere as far as i can see... but the cats stilll look like the main culprit, just dont understand why its not happening constantly

they are bloody expensive but i dont think that you can compensate with cats ive tried and had my finger burned!!!!

Cut them out, stick them to one side, replace with short sections of pipe. Put them back on at MOT time, make sure its a tidy job when you do. If you're lucky the MOT man won't even notice.

 

[Howard]

You'll get a bit more power too ... on my old CRX VTEC , i took the cat out and replaced it with pipe and it showed a 7% power increase !!

Its all gravy ....

 

[rajinder_1]

guys,
taking the cats off will make it noisey i think, i dont really want that especially as in summer when the roof is down...
I may bite the bullet and get new cats, although i will get it C02 check done for the mot first and see what the reading is...

 

[Howard]

It won't make it that much noiser , the cats aren't a silencer , although they will act as one a little bit , but not much ...

Personally i would save the £1.3k ....

Good luck , whatever you choose !

 

[Howard]

Oooops , double post ....

 

[rajinder_1]

i will keep you all posted, i will wait till the noise gets unbearable first. then will probably consider removing the internals of the cat and if i dont like it will probably end up getting new ones....

i am so surprised that you cant get a hold of eberspacer exhausts for the SL320, i would have thought that they would be able to sell them here but you cant get them anywhere other than MB who charge £1300 for the priviledge

 

[Dieselman]

. If you're lucky the MOT man won't even notice.

I don't understand this comment. The MOT tester is only interested in the vehicle at the time of the test, not before or after.

 

[Parrot of Doom]

I'm referring to the obvious modifications to the exhaust, which some MOT men might get flustered over.

I've never failed an MOT so I couldn't say if it would be a problem.

 

[Dieselman]

Not an issue as long as the joints are gas tight and the emissions are below the limit.

 

[Parrot of Doom]

Good to know

 

[television]

In the SL there are 4 cats, I have known cars to have had the lower ones removed and pass the MOT with no problem, as stated earlier,this does not effect the sound.

malcolm

 

[rajinder_1]

Hi Malc,
Good to hear from you... thanks for thet i think taht this will possibly be my first approach to the situation, and then see what happens, as ling as it passes a MOT and doesnt effect the noise it shouldnt be ok
the thing that gets me though is thatit only happens once the car is driving, it is smooth as silk when i rev it stationary? although some times i have heard it rattle when parked up but not that loud, seems to be getting worse...

Raj

 

[television]

Hi Malc,
Good to hear from you... thanks for thet i think taht this will possibly be my first approach to the situation, and then see what happens, as ling as it passes a MOT and doesnt effect the noise it shouldnt be ok
the thing that gets me though is thatit only happens once the car is driving, it is smooth as silk when i rev it stationary? although some times i have heard it rattle when parked up but not that loud, seems to be getting worse...

Raj

Hi Raj, I think I told you mine only ever did it crawling through a town center with high buildings so that everyone could stare at me.

Shame we cant just put some contact adhisive in the fuel tank.

Cheers Malcolm

 

[Bazzle]

I have used generic cats on cars inc my SLK230 for years, no probs. Many aftermarket ones are better than OE, esp the new metal ones.
I dont believe in removing them.

Bazzle

 

[rajinder_1]

SL320 Rattle

Guys,
I finally managed to get a sound/video recording of the noise please have a look and see what you think could be causing it.

Its intermittant and only occusr in the 1000-2500rpm range.....
i dont think its the cats as it would be constant, you will hear when i rev it goes away...

http://www.youtube.com/watch?v=ELLHf2oKpfc

thanks

Raj