Banging plate in the muffler? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

cliffsta · 01-24-2005, 08:16 PM

My truck makes a godawful banging clank kinda noise when under heavy load, especially in first, not really in second, but neither me nor my dad have woulnd it up in 2nd. When he drove it, he didn't get into it hard in second because he feared if it is the tranny, he didn't wanna stick a fork in it then and there. Kinda a really fast clanking noise. Could it be a plate in the muffler? its coming from right there under the driver's seat, so all we figure is the tranny or the muffler, the tranny mounts LOOK ok, but ya know...

The noise isn't coming from the hump area, its coming from right at the muffler.

Any ideas?

EricS76 · 01-24-2005, 08:28 PM

It's definately possible to be coming from the muffler, depending on what kind of muffler you have. If it's a "turbo" type muffler like a flowmaster, dynomax, most anything that's not a glasspack, it could rattle if one of the tubes or fins got loose inside. I had that happen with a dynomax. If it's a glasspack or any kind of muffler with fiberglass packing for noise reduction, shouldn't be anything in them to rattle.

cliffsta · 01-24-2005, 08:31 PM

its the original, rotted out to no end, stock muffler if that makes a difference.

Russell · 01-24-2005, 08:35 PM

Cliffsta, go get yourself a glasspack or something and replace that plugged up rotted peice of junk :P

jimfulco · 01-25-2005, 12:43 AM

Crawl up under the truck & hit stuff with your fist until you hear a familiar clank. This is best done when the exhaust system is not hot. My friend has a '75, & that's how we found the metal plate under the cab on the driver's side that made a noise every time he hit a bump. I don't know what purpose it serves, but it could be a heat shield for a long-gone catalyst or something. It seems to mount between the cab & the frame, so removal might have been difficult, but we just bent it into a little different shape & it doesn't clank much any more.

Trimman · 01-25-2005, 01:48 AM

jimfulco has a point. My 82 did the same thing in first. It was the heat sheld for the cat hiting the front u joint

Prerunner1982 · 01-25-2005, 12:06 PM

i was going to ask what do you mean under heavy load? the bed full of something? if so Trimman probably hit it dead on.. i have had the driveshaft hit the muffler before.. but that was because the shop welded it up wrong... my driveshaft will forever have two rings around it..

cliffsta · 01-25-2005, 01:16 PM

lol no. i ment heavy load, as in gettin up on the gas. gunnin it. heavy engine load.

Slonaker · 01-25-2005, 01:52 PM

It had a 305 do that in one of my cars. It turned out to be the thing on the right exhaust manifold that closes it off to make it warm up faster. I was worried that I had an engine knock, but it was just that thing cycling open and closed during acceleration. I never figured out why. I just disconnected it.

I have also had something break loos in a muffler and a catalytic converter. As others said, we found those by beating on stuff with my fist until something made the right sound.

I have a nasty sound coming from under my truck right now. I think (hope...) that it is a cracked flexplate.

Slonaker

apstguy · 01-25-2005, 02:56 PM

I had a noise everytime I would gun it or go around a corner fast. Ended up the tranny mount didn't have any bolts in it (EK!) and the engine and tranny would shift enough so the front u-joint would hit the catalatic converter heat shield. Check the tranny mount!

LOHRTBT · 01-25-2005, 04:15 PM

Do yourself a favor and DONT get a glasspack. haha Get an Aero Chamber or Flow or something.

cliffsta · 01-25-2005, 05:30 PM

I'm saving up for the manifold back dual exhuast in LMC. Its only 179, and it bolts up to the manifolds, and there is no welding required!!!!
im only about 60 bucks away........
Ill go check them things yall just said......

marvxyz · 01-25-2005, 09:40 PM

clifsta-- With that clanging, you may even notice a power loss. I've had a very similar problem. My truck would clang mercilessly when I backed up on a hill, and sometimes driving up a hill on a turn, it would make a ding sound. I finally found that my drive shaft yoke was hitting cat. cinverter shield. I think the transmission mount may be compressed due to age- lowering the drtive shaft a little, causing it to strike the converter shield. Good luck with your truck marvxyz Pgh. Pa.

marvxyz · 01-25-2005, 09:43 PM

clifsta-- PS I have a 80 GMC marvxyz Good luck!!

01-24-2005, 08:16 PM	#1
cliffsta Stepsides RULE Join Date: Jul 2004 Location: Pineville, LA Posts: 1,921	Banging plate in the muffler? My truck makes a godawful banging clank kinda noise when under heavy load, especially in first, not really in second, but neither me nor my dad have woulnd it up in 2nd. When he drove it, he didn't get into it hard in second because he feared if it is the tranny, he didn't wanna stick a fork in it then and there. Kinda a really fast clanking noise. Could it be a plate in the muffler? its coming from right there under the driver's seat, so all we figure is the tranny or the muffler, the tranny mounts LOOK ok, but ya know... The noise isn't coming from the hump area, its coming from right at the muffler. Any ideas? __________________ 1981 Chevy C10 Custom Deluxe Stepside 350 V8, headers, side exhausts, 3-speed auto SOLD 1980 Chevy C10 Custum Deluxe Stepside 305 V8, Edelbrock Performer Intake, Edelbrock 1406 600CFM 4-barrel, TH350C. Bent rod. SOLD 1984 GMC Sierra Classic Longbed 6.2L Diesel SOLD 2009 Kawasaki KLX-250S too many mods for this signature 1999 Honda Accord EX 4-cylinder, 17" Motegi Wheels 215/45/17 Sumitomo tires, Tein S-Tech lowering springs, KYB GR2 shocks, Acura TL 20mm rear swaybar, debadged, blackhoused headlights, Short-Ram Intake Cardomain of the Accord

01-24-2005, 08:28 PM	#2
EricS76 Registered User Join Date: May 2004 Location: Llano,TX Posts: 113	It's definately possible to be coming from the muffler, depending on what kind of muffler you have. If it's a "turbo" type muffler like a flowmaster, dynomax, most anything that's not a glasspack, it could rattle if one of the tubes or fins got loose inside. I had that happen with a dynomax. If it's a glasspack or any kind of muffler with fiberglass packing for noise reduction, shouldn't be anything in them to rattle. __________________ ‘66 Chevy C-10, long bed fleetside, 350, 3 on the tree, 4-7 drop. '77 chevy C-10 Custom Deluxe, 350, SM465 4 speed, flatbed. '80 jeep CJ-5. ‘14 Chevy 1500 Z71…

01-24-2005, 08:31 PM	#3
cliffsta Stepsides RULE Join Date: Jul 2004 Location: Pineville, LA Posts: 1,921	its the original, rotted out to no end, stock muffler if that makes a difference. __________________ 1981 Chevy C10 Custom Deluxe Stepside 350 V8, headers, side exhausts, 3-speed auto SOLD 1980 Chevy C10 Custum Deluxe Stepside 305 V8, Edelbrock Performer Intake, Edelbrock 1406 600CFM 4-barrel, TH350C. Bent rod. SOLD 1984 GMC Sierra Classic Longbed 6.2L Diesel SOLD 2009 Kawasaki KLX-250S too many mods for this signature 1999 Honda Accord EX 4-cylinder, 17" Motegi Wheels 215/45/17 Sumitomo tires, Tein S-Tech lowering springs, KYB GR2 shocks, Acura TL 20mm rear swaybar, debadged, blackhoused headlights, Short-Ram Intake Cardomain of the Accord

01-24-2005, 08:35 PM	#4
Russell Professional Grade Join Date: May 2003 Location: Fort McMurray, Alberta Posts: 7,915	Cliffsta, go get yourself a glasspack or something and replace that plugged up rotted peice of junk :P __________________ 1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap)

01-25-2005, 01:48 AM	#6
Trimman Registered User Join Date: Jan 2005 Location: Hixson TN. Posts: 74	jimfulco has a point. My 82 did the same thing in first. It was the heat sheld for the cat hiting the front u joint __________________ 82 C-10 Scottsdale LB owned since 89 350 crate vortec heads Crane 1.6 full rollers edelbrock 1406 edelbrock performer eps intake dynomax headers/flowmaster 70's BTO 700r4 level 3 custom 2 piece driveshaft 12 bolt gov loc w/3.08

01-25-2005, 12:43 AM	#5
jimfulco Registered User Join Date: May 2003 Location: Shreveport LA Posts: 3,170	Crawl up under the truck & hit stuff with your fist until you hear a familiar clank. This is best done when the exhaust system is not hot. My friend has a '75, & that's how we found the metal plate under the cab on the driver's side that made a noise every time he hit a bump. I don't know what purpose it serves, but it could be a heat shield for a long-gone catalyst or something. It seems to mount between the cab & the frame, so removal might have been difficult, but we just bent it into a little different shape & it doesn't clank much any more.

01-25-2005, 12:06 PM	#7
Prerunner1982 Registered User Join Date: Oct 2002 Location: Edmond, OK Posts: 5,906	i was going to ask what do you mean under heavy load? the bed full of something? if so Trimman probably hit it dead on.. i have had the driveshaft hit the muffler before.. but that was because the shop welded it up wrong... my driveshaft will forever have two rings around it.. __________________ Jon 1982 Chevy Silverado 350/th350.... RETIRED 1993 Jeep XJ 2 door(Cherokee) 4wd 4.0ltr/AX-15 (5spd)/NP231 .... Oklahoma Roll Call

01-25-2005, 01:16 PM	#8
cliffsta Stepsides RULE Join Date: Jul 2004 Location: Pineville, LA Posts: 1,921	lol no. i ment heavy load, as in gettin up on the gas. gunnin it. heavy engine load. __________________ 1981 Chevy C10 Custom Deluxe Stepside 350 V8, headers, side exhausts, 3-speed auto SOLD 1980 Chevy C10 Custum Deluxe Stepside 305 V8, Edelbrock Performer Intake, Edelbrock 1406 600CFM 4-barrel, TH350C. Bent rod. SOLD 1984 GMC Sierra Classic Longbed 6.2L Diesel SOLD 2009 Kawasaki KLX-250S too many mods for this signature 1999 Honda Accord EX 4-cylinder, 17" Motegi Wheels 215/45/17 Sumitomo tires, Tein S-Tech lowering springs, KYB GR2 shocks, Acura TL 20mm rear swaybar, debadged, blackhoused headlights, Short-Ram Intake Cardomain of the Accord

01-25-2005, 01:52 PM	#9
Slonaker Insert Witty Text Here Join Date: Oct 2002 Location: San Antonio, TX Posts: 3,415	It had a 305 do that in one of my cars. It turned out to be the thing on the right exhaust manifold that closes it off to make it warm up faster. I was worried that I had an engine knock, but it was just that thing cycling open and closed during acceleration. I never figured out why. I just disconnected it. I have also had something break loos in a muffler and a catalytic converter. As others said, we found those by beating on stuff with my fist until something made the right sound. I have a nasty sound coming from under my truck right now. I think (hope...) that it is a cracked flexplate. Slonaker __________________ '86 Chevy C10 (Sold 04/19/13 ) Stock '01 Silverado

01-25-2005, 02:56 PM	#10
apstguy LED King Join Date: Jan 2003 Location: Sacramento, CA Posts: 2,088	I had a noise everytime I would gun it or go around a corner fast. Ended up the tranny mount didn't have any bolts in it (EK!) and the engine and tranny would shift enough so the front u-joint would hit the catalatic converter heat shield. Check the tranny mount! __________________ Tyler 1985 C10 305 w/ Bowtie OD TH700R4 3.42 LSD 202,000 miles 2006 Ford Focus ZX3 5-speed Stick 2016 Chevy Spark EV Gone: 2002.5 VW GTI 24v VR6 Gone: 2008 VW R32

01-25-2005, 04:15 PM	#11
LOHRTBT BeWarE tHe eViL CrAnkTOe! Join Date: Oct 2002 Location: Yukon, OK Posts: 3,605	Do yourself a favor and DONT get a glasspack. haha Get an Aero Chamber or Flow or something. __________________ ~Dave~ You can call me Mike, Mike Oxlong - 1986 Chevy SWB - Stock for now - *1986 Chevy Custom SWB* *Stolen 6/26/05* - 1985 Chevy SWB SOLD - 1999 T/A Some mods www.cardomain.com/id/ramairdave AIM Screenname - Jester84

01-25-2005, 05:30 PM	#12
cliffsta Stepsides RULE Join Date: Jul 2004 Location: Pineville, LA Posts: 1,921	I'm saving up for the manifold back dual exhuast in LMC. Its only 179, and it bolts up to the manifolds, and there is no welding required!!!! im only about 60 bucks away........ Ill go check them things yall just said...... __________________ 1981 Chevy C10 Custom Deluxe Stepside 350 V8, headers, side exhausts, 3-speed auto SOLD 1980 Chevy C10 Custum Deluxe Stepside 305 V8, Edelbrock Performer Intake, Edelbrock 1406 600CFM 4-barrel, TH350C. Bent rod. SOLD 1984 GMC Sierra Classic Longbed 6.2L Diesel SOLD 2009 Kawasaki KLX-250S too many mods for this signature 1999 Honda Accord EX 4-cylinder, 17" Motegi Wheels 215/45/17 Sumitomo tires, Tein S-Tech lowering springs, KYB GR2 shocks, Acura TL 20mm rear swaybar, debadged, blackhoused headlights, Short-Ram Intake Cardomain of the Accord

01-25-2005, 09:40 PM	#13
marvxyz Registered User Join Date: Jan 2005 Location: Pittsburgh, Pa. Posts: 27	clifsta-- With that clanging, you may even notice a power loss. I've had a very similar problem. My truck would clang mercilessly when I backed up on a hill, and sometimes driving up a hill on a turn, it would make a ding sound. I finally found that my drive shaft yoke was hitting cat. cinverter shield. I think the transmission mount may be compressed due to age- lowering the drtive shaft a little, causing it to strike the converter shield. Good luck with your truck marvxyz Pgh. Pa.

01-25-2005, 09:43 PM	#14
marvxyz Registered User Join Date: Jan 2005 Location: Pittsburgh, Pa. Posts: 27	clifsta-- PS I have a 80 GMC marvxyz Good luck!!



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