Smarj_Z33

I recently bought an HKS catback exhaust for $400 off of Craigslist that was in very good condition. The only thing is it didn't come with the bolts or gaskets. So I found some gaskets that would work but I couldn't find any 7/16" bolts so I went with 1/2" and tapped the holes. Well now there's a rattling noise when the car first starts (mainly when idling on a hillside and after a little rev) but once it's warmed up, you can't hear the sound. Does anyone have an idea if the bolts I put it could be causing the rattling? Or is it just the exhaust hitting somewhere under the car?

travlee

iTrader: (8)

no way for us to know or diagnose the car over the internet....

travlee

iTrader: (8)

i would get the car up on stands, have a buddy start it while under it to see if you can pinpoint it

Smarj_Z33

I understand that, I just didn't know if the new bolts being in there would cause an issue with rattling. Thanks for the reply

travlee

iTrader: (8)

makes me wonder if the cat honeycomb is loose

travlee

iTrader: (8)

if they are tight, i dont see why they would

Smarj_Z33

I just need to get under it again like you suggested. I just want to find the problem soon, the exhaust sounds phenomenal but that rattling kills me at take off

travlee

iTrader: (8)

i would also check on the M brace under the car, my MotorDyne used to hit that and vibrate, triple check all the bolts, make sure every connection has a gasket, etc etc... good luck sir

Smarj_Z33

Will do. Thanks for the help

dcains

iTrader: (15)

Could also be a cheap Chinese knock-off "HKS" that just has rattles built-in.

Smarj_Z33

Nah, it has the genuine HKS welds and everything. When I first put it on, there wasn't a rattle but when I put new bolts in, that's when I started hearing it