heat - cooked my catalytic converter - The 1947 - Present Chevrolet & GMC Truck Message Board Network

lofat · 11-26-2003, 02:56 PM

about two weeks ago i noticed that the pipe out of the back of the catalytic converter had come loose. so today i take it to the muffler shop and we get it up and take a look under and you can see that it is cooked.

first thing is we notice the guy who owned the truck before me had them put 1 3/4" connector on the right portion of the Y pipe but also that the catalytic converter is a piece of sh*t. it's tiny and definitely wrong for that vehicle.

but the main issue is the heat. now i have never seen my heat gauge even hit the half way mark. usually once warmed up it hovers around 1/4 to 2/5 of the way. it doesn't seem like it runs too hot. never overheated even in the bumper to bumper traffic in the hot CA afternoon commute. fluids are all good too.

so is this new thermostat time or what....

i am at a loss, but this guy does really nice work, and the last thing i want to do is cook it again.

any ideas are appreciated.

Cheers,
scott

**old Rusty C10** · 11-26-2003, 04:35 PM

hollow out the bad boy and just hook the exhaust together

BigRed · 11-26-2003, 04:43 PM

Quote:

Originally posted by old Rusty C10
hollow out the bad boy and just hook the exhaust together

Don't think he can get away with that, being in Cali.

lofat · 11-26-2003, 04:45 PM

not till 2006

**swervin ervin** · 11-26-2003, 05:03 PM

I cooked a muffler that was too close to the cat once. It was a Dynomax Superturbo. That thing got so hot, it busted the seam. The fiberglas mat inside was nothing but crystals.

I suggest you make sure you are not running too rich. If raw fuel vapors reach the cat, it will overheat it in a hurry. When you start modding these trucks with cats, it's a touchy thing. You have to make sure you have a good ignition system and the fuel is right. It took me many hours of tuning to get my combination to where it worked good.

Also, a good cat is real important. Don't try to get by with a cheap one. It won't last.

lofat · 11-26-2003, 05:07 PM

right on mike, - i think i am running too rich. i know in the mornings it will start right up and then putter out if i give it too much gas in the first 30 seconds or so. also there is a half second of hesitation when i gun it as well.

does it seem odd that the temp guage hovers so low?

**swervin ervin** · 11-26-2003, 05:52 PM

I don't know about your engine temp. You do have a thermosat, right? I run a 180 degree stat. It's critical to have the engine operating at the proper temps. If it's not, it will make the choke try to close some. If you run too cool of a stat, like a 160, all the sensors and switches don't fully open, causing it to run more rich. The TVS's work at 160 degrees.

RussTburb · 11-26-2003, 06:28 PM

I work at a "muffler" shop and we see a lot of burned up cats. The reason has very little to do with engine temp but all to do with exhaust temps. Too lean of an exhaust cause heat in the exaust as well as unburned fuel! Ignintion timing that is stuck advanced can put a ton of heat in the exahust as well. Can the "muffler" shop analyze your trucks emission? that would be what I would suggest. good luck!

Tom · 11-26-2003, 06:48 PM

I've melted 3 cats so far. I just left 2 of em on and let em melt away. I still passed emissions better then when the cats worked. You don't have AIR injection or even EGR do you? Im pretty sure thats why mine died, cause I have neither to inject cold air into the exaust to cool it down. When I only had the cats on and no exaust you could see the cats glowing bright red inside when I let off the gas ans was slowing down.

lofat · 11-26-2003, 06:51 PM

good idea. this guy is an exhaust specialist. not sure if he has the equiptment but i'll run it by him. he seems like a real cool cat. actually gave me a ride home in his truck after i dropped mine off. never had that happen before. i got to see a few of the cars he was working on the lifts and he does really nice work.

now that you mention timing, every so often the truck likes to over run a little. mostly if it is hot, or been driving for a while. but it's not consistent.

lofat · 11-27-2003, 01:35 AM

well, cool. my exhaust is fixed. i decided to stick with the single flowmaster for now. but he replaced everything from (and including) the cat forward. some fater pipes, minimal angles and still out before the tire. i noticed the response is much better.

now to tweek the carb and have the timing checked.

oh, is it normal to smell the welds after getting exhaust work done? i drove it a couple miles and when i parked it smelled like some one was mig welding.

11-26-2003, 02:56 PM	#1
lofat Rollin' Member Join Date: May 2003 Location: Hayward, California Posts: 240	heat - cooked my catalytic converter about two weeks ago i noticed that the pipe out of the back of the catalytic converter had come loose. so today i take it to the muffler shop and we get it up and take a look under and you can see that it is cooked. first thing is we notice the guy who owned the truck before me had them put 1 3/4" connector on the right portion of the Y pipe but also that the catalytic converter is a piece of sh*t. it's tiny and definitely wrong for that vehicle. but the main issue is the heat. now i have never seen my heat gauge even hit the half way mark. usually once warmed up it hovers around 1/4 to 2/5 of the way. it doesn't seem like it runs too hot. never overheated even in the bumper to bumper traffic in the hot CA afternoon commute. fluids are all good too. so is this new thermostat time or what.... i am at a loss, but this guy does really nice work, and the last thing i want to do is cook it again. any ideas are appreciated. Cheers, scott __________________ :: 1977 C10 cheyenne :: :: 1973 new yorker brougham :: for sale - $1,500 lofat productions

11-26-2003, 04:35 PM	#2
old Rusty C10 Robert Olson Transport Join Date: Oct 2002 Location: recent transplant to NC USA Posts: 20,277	hollow out the bad boy and just hook the exhaust together __________________ Bob 1951 International running on a squarebody chassis "If a man's worth is judged by the people he associates himself with, then i am the richest man in the world knowing some of the fine people of this board" http://67-72chevytrucks.com/vboard/a...t.php?f=25&a=9 (you can review the site rules here!) PM Me for your vehicle/parts hauling needs in the North East US or see my Facebook page Robert Olson Transport Live each day to the fullest.. you never know when fate is going to pull the rug out from under you... I hate cancer!!

11-26-2003, 04:45 PM	#4
lofat Rollin' Member Join Date: May 2003 Location: Hayward, California Posts: 240	not till 2006 __________________ :: 1977 C10 cheyenne :: :: 1973 new yorker brougham :: for sale - $1,500 lofat productions

11-26-2003, 05:03 PM	#5
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	I cooked a muffler that was too close to the cat once. It was a Dynomax Superturbo. That thing got so hot, it busted the seam. The fiberglas mat inside was nothing but crystals. I suggest you make sure you are not running too rich. If raw fuel vapors reach the cat, it will overheat it in a hurry. When you start modding these trucks with cats, it's a touchy thing. You have to make sure you have a good ignition system and the fuel is right. It took me many hours of tuning to get my combination to where it worked good. Also, a good cat is real important. Don't try to get by with a cheap one. It won't last. __________________ Mike 1985 Chevy C-10

11-26-2003, 05:07 PM	#6
lofat Rollin' Member Join Date: May 2003 Location: Hayward, California Posts: 240	right on mike, - i think i am running too rich. i know in the mornings it will start right up and then putter out if i give it too much gas in the first 30 seconds or so. also there is a half second of hesitation when i gun it as well. does it seem odd that the temp guage hovers so low? __________________ :: 1977 C10 cheyenne :: :: 1973 new yorker brougham :: for sale - $1,500 lofat productions

11-26-2003, 05:52 PM	#7
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	I don't know about your engine temp. You do have a thermosat, right? I run a 180 degree stat. It's critical to have the engine operating at the proper temps. If it's not, it will make the choke try to close some. If you run too cool of a stat, like a 160, all the sensors and switches don't fully open, causing it to run more rich. The TVS's work at 160 degrees.

11-26-2003, 06:28 PM	#8
RussTburb Registered User Join Date: Mar 2002 Location: Blaine,Wa. U.S.A Posts: 261	I work at a "muffler" shop and we see a lot of burned up cats. The reason has very little to do with engine temp but all to do with exhaust temps. Too lean of an exhaust cause heat in the exaust as well as unburned fuel! Ignintion timing that is stuck advanced can put a ton of heat in the exahust as well. Can the "muffler" shop analyze your trucks emission? that would be what I would suggest. good luck! __________________ "Red-heads not war-heads, Blondes, not bombs, Brunettes, not fighter jets!" Fligh of the Choncords 72 burb 3/4 ton 2wd 06 2500 suburban 8.1L 4x4 84 chev 4x4 diesel 96 Geo Metro with the 4cylbb, lol! Almost 300k just won't die! 89 Honda Civic, runs on the smell of an oily rag! 2008 Aerolite 26qs Travel Trailer (aka "THE BARN")

11-26-2003, 06:48 PM	#9
Tom driving is in my blood Join Date: Dec 1999 Location: Mesa AZ Posts: 5,714	I've melted 3 cats so far. I just left 2 of em on and let em melt away. I still passed emissions better then when the cats worked. You don't have AIR injection or even EGR do you? Im pretty sure thats why mine died, cause I have neither to inject cold air into the exaust to cool it down. When I only had the cats on and no exaust you could see the cats glowing bright red inside when I let off the gas ans was slowing down. __________________ -78 c10 short/step: 388cid, M20, 5/5 drop, lots more. Playtoy and first vehicle. -98 c1500 x-cab: 5.7L, 17" rims, 5/6 drop, flowmaster, helper bags,NBS rear disk brakes. -02 Suburban 4x4: leveled front -CBR600F4i, CBR600RR, CBR1000RR, and standup skis DISCLAIMER: I cant spell for the life of me.

11-26-2003, 06:51 PM	#10
lofat Rollin' Member Join Date: May 2003 Location: Hayward, California Posts: 240	good idea. this guy is an exhaust specialist. not sure if he has the equiptment but i'll run it by him. he seems like a real cool cat. actually gave me a ride home in his truck after i dropped mine off. never had that happen before. i got to see a few of the cars he was working on the lifts and he does really nice work. now that you mention timing, every so often the truck likes to over run a little. mostly if it is hot, or been driving for a while. but it's not consistent. __________________ :: 1977 C10 cheyenne :: :: 1973 new yorker brougham :: for sale - $1,500 lofat productions

11-27-2003, 01:35 AM	#11
lofat Rollin' Member Join Date: May 2003 Location: Hayward, California Posts: 240	well, cool. my exhaust is fixed. i decided to stick with the single flowmaster for now. but he replaced everything from (and including) the cat forward. some fater pipes, minimal angles and still out before the tire. i noticed the response is much better. now to tweek the carb and have the timing checked. oh, is it normal to smell the welds after getting exhaust work done? i drove it a couple miles and when i parked it smelled like some one was mig welding. __________________ :: 1977 C10 cheyenne :: :: 1973 new yorker brougham :: for sale - $1,500 lofat productions



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