Exhaust vibration/rattle at cold start?

[Foobar]

I've got the Perrin headerback and recently (now that I've been able to drive with windows open in the mild weather) I've noticed that the exhaust makes a bit of a vibration or rattle sound for a second at cold start. I'm going to put the car up and check that everything's still tightened to spec, but was wondering if anyone else noticed this and perhaps it was just normal?

Maybe part of the exhaust system is too close to another part of the car and during the cold start routine there's enough vibration in the system to make it hit for a second?

6MT, in case anyone was wondering - I know that there were some cases of the exhaust being tight with the auto, so that's not it.

[shu5892001]

My perrin un-resonated exhaust does it too, but only when it's very cold and it only happens for like 1 nano second.

[Tylub]

Originally Posted by Foobar

I've got the Perrin headerback and recently (now that I've been able to drive with windows open in the mild weather) I've noticed that the exhaust makes a bit of a vibration or rattle sound for a second at cold start. I'm going to put the car up and check that everything's still tightened to spec, but was wondering if anyone else noticed this and perhaps it was just normal?

Maybe part of the exhaust system is too close to another part of the car and during the cold start routine there's enough vibration in the system to make it hit for a second?

6MT, in case anyone was wondering - I know that there were some cases of the exhaust being tight with the auto, so that's not it.

if you have the non resonated, i say just get used to it?
maybe the piping is cold because i get this as well

after it's warm, it completely goes away. and only lasts for maybe a few seconds.

what kind of sound are you experiencing? can you try to be a little more specific?

another theory could be the studs connecting the exhaust manifold to the overpipe and perhaps that's loose?

[DarkSunrise]

Same here -- Perrin NR.

[SkAsphalt]

SRT header back, lasts until it is warmed up. the car is v8 short block loud with a cold start (just not v8 deep)

[Foobar]

Thanks guys - yeah I've got the unresonated catted headerback. It's not a big deal to "get used to" as Tylub suggests, I just wanted to make sure it was normal. I never noticed it before but now that it's warmer out, I've had a few opportunities to start the car with my windows open and I noticed the sound, sort of a metallic rattling sound as if part of the exhaust was just touching part of the car.

I put the car up and confirmed that all of the bolts and bands were tightened to spec, all the way from the header to the last muffler hanger. I don't see evidence of exhaust leak anywhere in the system. I also ran my fingers all along the system checking to see if it was butting up against part of the car, but aside from the connection to the header, the frontpipe hanger, and the muffler hangers, it's completely clear. The closest it gets to the car is by the rear crossmember, I'd say it has about a centimeter of space between the top of the pipe to the bottom of the crossmember.

Looks like it's just something inside of the exhaust that wakes up for a second at start, but then goes away. Based on other responses here, looks like it's completely normal.

Thanks guys!

[PERRIN_Mladen]

Originally Posted by Foobar

Thanks guys - yeah I've got the unresonated catted headerback. It's not a big deal to "get used to" as Tylub suggests, I just wanted to make sure it was normal. I never noticed it before but now that it's warmer out, I've had a few opportunities to start the car with my windows open and I noticed the sound, sort of a metallic rattling sound as if part of the exhaust was just touching part of the car.

I put the car up and confirmed that all of the bolts and bands were tightened to spec, all the way from the header to the last muffler hanger. I don't see evidence of exhaust leak anywhere in the system. I also ran my fingers all along the system checking to see if it was butting up against part of the car, but aside from the connection to the header, the frontpipe hanger, and the muffler hangers, it's completely clear. The closest it gets to the car is by the rear crossmember, I'd say it has about a centimeter of space between the top of the pipe to the bottom of the crossmember.

Looks like it's just something inside of the exhaust that wakes up for a second at start, but then goes away. Based on other responses here, looks like it's completely normal.

Thanks guys!

From what you are describing, that sounds normal. Our shop car does the same thing on a cold start.

If you feel like it could be something more, make a video of it and get it over to us and we can look into it! You have done the steps that I would recommend you do in order to check for an exhaust leak or a loose bolt.

As I stated before, it sounds completely normal to me, but I understand the need to double check !

If you have any more concerns, just let me know here or via PM!

[SkAsphalt]

I now have added vibrations throughout my car at certain points in my rev range... I blame my resonator for that. So I will be slowly finding them and adding stuff to remove the rattles/vibration sounds. I like the louder exhaust but also want a smooth sounding car.

So i guess I took a few steps forward and a few steps back but I love my car