Metal expanding sound?

[Manual Calais]

Hey, after going for a drive when i come to a stop and turn my car off it ticks like mad, from the motor and possily the exhaust too. I'm pretty sure its just metal expanding or what ever the opposite of expanding is, but am i wrong or are the ny solutions to fix this embarrassing and anoying problem?

Thanks

[GRPABT1]

Mine does it too, like you said it's usually just the exhaust cooling down

[Manual Calais]

yeah but it mainly comes from my motor

[Andrew426]

The noise is your cat converter cooling down - It will stop doing it after you gut your cat.

I think you should.

Seriously, embarrasing and annoying?

[Manual Calais]

welll yeah when u pull up to a park and its doing it every one looks and probably thinks your driving a piece of shit haha it goes for a good 20 seconds and is pretty loud and im sure its not only from my cat, its from my motor too

[Andrew426]

Its a 20 year old commodore bro, wont they be thinking that already?

[Manual Calais]

i was waiting for that reply... and that doesnt mean its a piece of shit... it looks alright... goes alright... sounds allright apart from this one ticking sound.... andif it wasnt there they would be less incinded to be looking in the first place to think its a 20 year old piece of shit was after any solutions and thanks for the idea with the cat, was gunna do it anyway, but still after one for the motor or maybe what actually in the motor is making this sound..

Thanks for the reply buddy

[SP00KSTER]

don't gut the cat mate, it's illegal. if your worried about restriction or something then buy a new one.
the noise is common to all older commodores. i know mine does it. The old muscle cars made that sound so just think of it as the inner muscle car trying to break out of your car. lol

[Manual Calais]

i wont be gutting it ill be getting a hi flow when i do the extractors which im not doing until i do my heads, and yeah its just a mechanical monster

[ryan21]

fairly sure all cars make this noise... mabey some more than others but still..

[Manual Calais]

my dads xf ute doesnt my mum au doesnt my sisters ed doesnt, my bosses 2000 hilux doesnt, 2 tradies i work with have xd and vz thunder that both dont so thats a pretty high rate that dont

[DLFHUB666]

Its a common nosie, its just the engine/exhaust cooling down my vx ss does it all the time. nothing you can do about it, except not start the car then it wont heat up an wont tick as it contracts when it cools down.

[Manual Calais]

cheers for the str8 forward answer but do you know why it doesnt happen to every single car?

[Andrew426]

I think its to do with the construction of your cat. A lot of cars have a heavy cast iron housing for the cat, so they dont make the noise. But commodores have a pressed sheet stainless or mild steel housing, which is why they do it.

[DLFHUB666]

I think you will find all cars do it some are just louder than others.

[vps231]

My dads au does it when its hot enough, My vp does it every now and then and more so after i thrash it.

I highly doubt its your motor.

[Manual Calais]

okay thanks guys, i guss ill see how the problem goes when i replace my cat with a hi flow one, but i open my bonnet and put y ear right next to tthe motor and can hear it.. louder then under my car

[Andrew426]

Yeah sometimes your engine will make the same noise. Not sure what causes it though, could be hot oil in the pressed steel sump. Once it has no airflow over it, the sump starts to get warmer and that would cause the metal to expand and tick.

Not really sure about that, its just a theory

[GRPABT1]

It's just metal cooling down, you can't narrow it down to one part because many bits of metal get hot and expand and contract in a car. It's not just the cat.

[DLFHUB666]

What he said ^^^^^

[ucwepn]

yep its just the metal cooling down, metal expands when hot and contracts when cooling, some cars will not do this as mass producing engines isn't as precise as it could be (some are better than others). My VN 5L did this especially when I was giving it a squirt.

[Circlotron]

Had a metallic clanking noise after the engine was turned off coming from around the inlet manifold on a 253 VH years ago. No, not running on but just as loud. The top radiator hose was pulsating like mad too. Ended up splitting the seam on the top tank off the radiator. Turned out it was a bad thermostat. Really weird.

[Circlotron]

Wrapping up the exhaust pipes with that bandage stuff is =really= good for stopping that tinny, chittery noise from coming through the walls of the pipe. Might help with clicky pipe noises. A bit harder to wrap up the entire cat though. Maybe you could build a tin box around it and stuff it with hi temp insulation.

[rambunctious]

Hmmm, considering you state it is worse in the engine area, have you given any thought it may be boiling caused by thermostat as already mentioned or there are air lock pockets in cooling system.

If it is so loud it turns heads, then it is more than exaust expanding.

[Circlotron]

Yeah, the thermostat thing sounded like dropping a hammer about 150mm onto the inlet manifold. No exaggeration.