Catalytic Converter Rattles When Below Freezing?? - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

Lizey93 · 01-11-2018, 05:07 AM

For the last month or so ever since Michigan finally got cold, Christine has made an AWFUL rattling/buzzing noise from the front of the car when I first start it up in the morning and am letting it warm up. This noise persists until the engine warms up and then it goes away. Today, however, it was about 50 degrees and the noise completely went away? I am having the dealer check it out under warranty but they can't get me in for a couple of weeks but I was just wondering if anyone else on here has experienced this? Its a 2013 LFX. This coincided with my gas mileage dropping from 25-26ish to 19-20ish which leads me to believe I have catalytic converter issues but I am unsure.

Dragonman · 01-11-2018, 07:29 AM

Took my wife's '04 Malibu in for a bad rattle after it had to sit outside in sub zero temps over new years. I thought it could've been anything between valve or piston clatter to a pulley or pump going bad. The oil had just been changed a couple weeks earlier so I hoped it wasn't piston or valves not getting oil. Rolled it to my mechanic and he went hunting and discovered the front cat is going out. I heard it quietly rattling this morning after sitting in a 60 degree garage so I reckon I'll be squeezing my wallet in the near future for the cash to get it replaced.

Just for your information he quoted me $600 installed for the damn thing. I've seen the part since for as little as $99 and over $400 so.... I asked about deleting it and going with a "test pipe" but he demurred vigorously. We're going to wait until the motor starts choking a bit or the noise gets just to annoying.

Good luck.

Gasoholic · 01-11-2018, 08:42 AM

If your cats rattle its time for new cats. Bottom line.

camguynj · 01-11-2018, 08:59 AM

Had severe vibrating/humming upon cold start for minute or so (passenger side only) when temp below 40. Problem went away when I switched to Solo HF cats

Dragonman · 01-11-2018, 09:19 AM

Quote:

Originally Posted by Gasoholic

If your cats rattle its time for new cats. Bottom line.

I agree. Holidays and mods to house over the last year has my wallet fairly empty. It'll get replaced when it has to and can be. Right now, the car is running normally, except for the noise, so it hasn't reached the has to stage yet.

NC_SS · 01-11-2018, 09:46 AM

I have a rattle on cold starts with my LT's, probably just a heat shield that needs pushed back in

Gasoholic · 01-11-2018, 10:58 AM

A heat shield rattle is different. If the cats are rattling internally the honey comb material is coming apart inside. It can become lodged in the pipes and choke off your exhaust.
In the worst case it can cause stalling and no start conditions. And it came happen out of the blue like driving down the e-way your engine suddenly stalls. More often it just causes reduced power but occasionally it'll leave you having to call a tow truck.
Factory cats have a pretty good warranty. They ought to, they cost like an arm and a leg.
If you have factory cats I'd try to get them repaired under warranty.

Hixson · 01-11-2018, 11:01 AM

Quote:

Originally Posted by Dragonman

I agree. Holidays and mods to house over the last year has my wallet fairly empty. It'll get replaced when it has to and can be. Right now, the car is running normally, except for the noise, so it hasn't reached the has to stage yet.

Don't know if this is something that interests you but Id do a pay it forward if it is. I'm installing LT headers and high flow cats soon so I will be disposing of my stock cats from my 2015 1ss. Any interest in having them sent your way? Car has 28K on the odo so I would suspect cats are just fine

NC_SS · 01-11-2018, 11:31 AM

Quote:

Originally Posted by Gasoholic

A heat shield rattle is different. If the cats are rattling internally the honey comb material is coming apart inside. It can become lodged in the pipes and choke off your exhaust.
In the worst case it can cause stalling and no start conditions. And it came happen out of the blue like driving down the e-way your engine suddenly stalls. More often it just causes reduced power but occasionally it'll leave you having to call a tow truck.
Factory cats have a pretty good warranty. They ought to, they cost like an arm and a leg.
If you have factory cats I'd try to get them repaired under warranty.

I don't have cats so that's why I figure it's a heat shield because my car is loud

Dragonman · 01-11-2018, 01:44 PM

Quote:

Originally Posted by Hixson

Don't know if this is something that interests you but Id do a pay it forward if it is. I'm installing LT headers and high flow cats soon so I will be disposing of my stock cats from my 2015 1ss. Any interest in having them sent your way? Car has 28K on the odo so I would suspect cats are just fine

Thanks for the offer but the cat I need is for an '04 Malibu. I'd be interested in the information on those quad halo lights you posted in another thread though.

01-11-2018, 05:07 AM	#1
Lizey93 Drives: 2013 Camaro 2LT/RS Join Date: May 2017 Location: Wyandotte, MI Posts: 52	Catalytic Converter Rattles When Below Freezing?? For the last month or so ever since Michigan finally got cold, Christine has made an AWFUL rattling/buzzing noise from the front of the car when I first start it up in the morning and am letting it warm up. This noise persists until the engine warms up and then it goes away. Today, however, it was about 50 degrees and the noise completely went away? I am having the dealer check it out under warranty but they can't get me in for a couple of weeks but I was just wondering if anyone else on here has experienced this? Its a 2013 LFX. This coincided with my gas mileage dropping from 25-26ish to 19-20ish which leads me to believe I have catalytic converter issues but I am unsure. __________________ 2019 Chevy Colorado LT 2013 Camaro 2LT/RS "Christine" - SOLD 10/15/18 1993 Jeep Wrangler YJ 1993 GMC K1500 "Old Blue" 1943 Farmall A

01-11-2018, 07:29 AM	#2
Dragonman Drives: 2015 1LT OBE Join Date: Oct 2015 Location: KY Posts: 509 View My Garage	Took my wife's '04 Malibu in for a bad rattle after it had to sit outside in sub zero temps over new years. I thought it could've been anything between valve or piston clatter to a pulley or pump going bad. The oil had just been changed a couple weeks earlier so I hoped it wasn't piston or valves not getting oil. Rolled it to my mechanic and he went hunting and discovered the front cat is going out. I heard it quietly rattling this morning after sitting in a 60 degree garage so I reckon I'll be squeezing my wallet in the near future for the cash to get it replaced. Just for your information he quoted me $600 installed for the damn thing. I've seen the part since for as little as $99 and over $400 so.... I asked about deleting it and going with a "test pipe" but he demurred vigorously. We're going to wait until the motor starts choking a bit or the noise gets just to annoying. Good luck. __________________ _______-2015 1LT JUSTICE----------------------------------1997 B12-___________

01-11-2018, 09:46 AM	#6
NC_SS Drives: 2012 M6 Camaro SS (RIP) Join Date: Nov 2014 Location: Virginia Posts: 1,684	I have a rattle on cold starts with my LT's, probably just a heat shield that needs pushed back in __________________ Speed engineering 1 7/8 LTs, CAI inc Cold Air Intake, offroad connectors, Solo performance axle back with J pipes, tune, and in need of a driver mod LOL

01-11-2018, 08:42 AM	#3
Gasoholic Drives: o Join Date: Jun 2017 Location: under a rock Posts: 220	If your cats rattle its time for new cats. Bottom line.

01-11-2018, 08:59 AM	#4
camguynj Drives: '13 SS/RS LS3 BRM Cammed NPP Join Date: Jan 2013 Location: NJ Posts: 3,812 View My Garage	Had severe vibrating/humming upon cold start for minute or so (passenger side only) when temp below 40. Problem went away when I switched to Solo HF cats

01-11-2018, 10:58 AM	#7
Gasoholic Drives: o Join Date: Jun 2017 Location: under a rock Posts: 220	A heat shield rattle is different. If the cats are rattling internally the honey comb material is coming apart inside. It can become lodged in the pipes and choke off your exhaust. In the worst case it can cause stalling and no start conditions. And it came happen out of the blue like driving down the e-way your engine suddenly stalls. More often it just causes reduced power but occasionally it'll leave you having to call a tow truck. Factory cats have a pretty good warranty. They ought to, they cost like an arm and a leg. If you have factory cats I'd try to get them repaired under warranty.