VZ V6 Rattle!

Summer-Sickness · #1 23-11-2008, 04:11 PM

hey guys got a VZ V6 exec, when im drivin at low speeds and go to accelerate slightly it starts to rattle, n if i hold the accelerator at a set point it continues to rattle, i think its probably because of the noise of the exhaust being at a certain note which causes it to resonate? sound good to anyone else?

it doesnt do it so much in idol but occasionally it does, it was doing it this morning so i got down n it seems to be coming from just behind the cat on the drivers side... i have a twin 2.5" cat back on my car, i didnt notice the noise till after i got the exhaust done, but the part where the noise is coming from is still old stock part of the exhaust, just wondering if this is a common issue or anyone have any ideas wot it could be? i dont have a great deal of car knowledge but it kinda just seems like something loose, or a rubber grommet has worn?

any help would be appreciated.

Torquative · #2 23-11-2008, 04:18 PM

Im curious too ...

Ivfe bolted an LS1 exhaust on and recently have had a rattle at idle, but mainly at low speeds.

Ive also noticed at 3000 RPM it has like an induction sound which goes away shortly after it passes 3000, like if Im pulling onto a motorway and giving it a bootfull

Ive noticed it at idle when I put my ear near the right hand rear wheel and I can see the right side muffler vibrating like theres no tomorrow whereas the left one is still ...

So yeh anyone with any ideas?????

andyman · #3 24-11-2008, 05:27 PM

have the heat sheilds checked out, its quite common for them to rattle at certain pitches, mine has a slight rattle, kinda like a dull metallic grrrrrrring sort of noise,

matt, check the mounts, one side might be holding more weight than the other if you know what i mean,

i think the resonance change will probably be from the intake cam advancing or retarding, the noise is more noticeable if the windows down and the stock single pipe fitted

Benboy · #4 24-11-2008, 05:33 PM

Get the entire exhaust system checked. Sounds like it's starting to 'fall apart' the rattle could be from bits 'n' pieces inside moving around. Same thing happened to a VN I once owned. Spent ages trying to trace the source eventually found rusted piece of metal in the system after muffler and before curved bend over the axle.

vy-346 · #5 24-11-2008, 06:17 PM

My brother had this in his SV6. Was a loose oxy sensor (they are screwed into exhaust) somethin to check.

Summer-Sickness · #6 24-11-2008, 07:28 PM

Quote:

Originally Posted by andyman

have the heat sheilds checked out, its quite common for them to rattle at certain pitches, mine has a slight rattle, kinda like a dull metallic grrrrrrring sort of noise,

matt, check the mounts, one side might be holding more weight than the other if you know what i mean,

i think the resonance change will probably be from the intake cam advancing or retarding, the noise is more noticeable if the windows down and the stock single pipe fitted

firstly thanks for the reply,

i got down again and had a look, if the heat sheilds are what i think they are then i think u may have hit the nail on the head, they look like they're vibrating alot... theres a few things that look like metal hose clamps ill get down there with a screwdriver n see if they need tightening when i get my tools from work tomorrow.

Quote:

Originally Posted by Benboy

Get the entire exhaust system checked. Sounds like it's starting to 'fall apart' the rattle could be from bits 'n' pieces inside moving around. Same thing happened to a VN I once owned. Spent ages trying to trace the source eventually found rusted piece of metal in the system after muffler and before curved bend over the axle.

thanks will try a couple of other suggestions first myself and if i cant sort it out ill have to take it in n get it looked at. the cat back only went on less than 2 months ago so hopefully its nothing like that.

Quote:

Originally Posted by vy-346

My brother had this in his SV6. Was a loose oxy sensor (they are screwed into exhaust) somethin to check.

where abouts on the exhaust system are they?... and what do they look like... haha :P

also would like to add i couldnt get it to make the rattle in idol today, so i lightly put my foot on the throttle, when the revs were around 1100rpm it made the rattle, i held the revs there and it made the rattle constantly till i backed off the throttle.

andyman · #7 24-11-2008, 08:12 PM

safely jack the car up, get a screwdriver, or a stethoscope get your mrs to rev it and start probing for the noise

Torquative · #8 24-11-2008, 08:36 PM

andy thanks for the advice, i would never have thought of that.

Its obvious the rattle is metallic and its caused by that drivers side pipe rattling, but mines only at low revs/idle.

I re-checked the bracket last time and all was sweet, so I dunno.

I might have to jack the car back up and have a look. Otherwise I'm just gonna wait til Jan when its up on a hoist.

SS - let us know how you go

Ben, thats food for thought, but I'd be worried if a 12 month old exhaust is starting to fall apart internally. Plus I think this may be a common issue because we're both experiencing it after doing the same modification.

andyman · #9 25-11-2008, 04:03 PM

Quote:

Originally Posted by Torquative

andy thanks for the advice, i would never have thought of that.

Its obvious the rattle is metallic and its caused by that drivers side pipe rattling, but mines only at low revs/idle.

I re-checked the bracket last time and all was sweet, so I dunno.

I might have to jack the car back up and have a look. Otherwise I'm just gonna wait til Jan when its up on a hoist.

SS - let us know how you go

Ben, thats food for thought, but I'd be worried if a 12 month old exhaust is starting to fall apart internally. Plus I think this may be a common issue because we're both experiencing it after doing the same modification.

i was thinking that cause you welded the extra bracket in to make way for the twin pipe, might not be welded in correctly, or the rubber mounts arnt the same,

Pub24/7 · #10 25-11-2008, 04:37 PM

Problem found?? if it sounds like its coming from the engine my guess it'd be one of the 3 timing chains

Torquative · #11 25-11-2008, 05:51 PM

i havent looked at mine since but i do know with mine its vibration caused by the RHS pipe as I can see it physically vibrating while the LHS doesnt, and when you chock something under it like a block of wood it stops the noise.

Andy ALL the mounts were changed and are all exactly the same, theres only one type of rubber mount.

Summer-Sickness · #12 27-11-2008, 08:00 PM

Quote:

Originally Posted by Torquative

i havent looked at mine since but i do know with mine its vibration caused by the RHS pipe as I can see it physically vibrating while the LHS doesnt, and when you chock something under it like a block of wood it stops the noise.

Andy ALL the mounts were changed and are all exactly the same, theres only one type of rubber mount.

yeh i believe mine is too... i held it in place with a pair of pliers (grabbed the edge of the heat sheild) n it seemed to have stopped. the part of the exhaust that is rattling is still completely stock on mine tho... thats what doesnt make sense... unless the mounts have just worn down.