rattle rattle thunder clatter boom boom boom... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

05crewcab · 03-31-2012, 11:42 PM

Strange thing started happening this week...

When my truck is moving and under load, (accelerating, driving up a hill, etc.) I have this rather loud clattering noise coming from someplace in or near the engine bay. It doesn't happen if I don't have my foot in it, and won't make the noise in Park.

I crawled under the truck tonight and checked everywhere for things touching the drivetrain...exhaust hangers, trans cooler lines, kickdown cable, speedo cable, PS lines, loose brackets, starter, etc. I also checked and greased my u-joints and the carrier bearing is in good shape.

Anyone have any ideas on what to check next? The motor sounds fine when revving in Park, and doesn't make this noise at idle or over 3000 RPM... I'm stumped.

oldschool18 · 04-01-2012, 12:32 AM

does it seem to be missing when its doing this

05crewcab · 04-01-2012, 12:41 AM

I don't think it is missing/stumbling, etc. the power seems normal as near as i can tell.

steves1967 · 04-01-2012, 12:42 AM

Detonation?? What's the engine timing?

oldschool18 · 04-01-2012, 12:45 AM

mine was doing that then it started to miss and it was a bad plug wire, and mine only did it when it was under a load....going up hill.....accelerating quick

05crewcab · 04-01-2012, 12:46 AM

No idea what the timing is unfortunately...I haven't touched it since I bought it two years ago.

05crewcab · 04-01-2012, 01:08 AM

Quote:

Originally Posted by oldschool18

mine was doing that then it started to miss and it was a bad plug wire, and mine only did it when it was under a load....going up hill.....accelerating quick

That's intersting. I'll have to check the plug wires...I didn't think such a loud noise could be a bad wire. it literally sounds like something is banging off the fan.

hotrod100 · 04-01-2012, 02:47 AM

Check for a broken flex plate. I just got done replacing one in a Suburban that was doing the exact same thing. It ended up having two small cracks around the mounting bolts and wouldn't make any noise until you got on it a bit then it would start snapping and popping. We really heard it when we were towing the boat! Unfortunately you may not be able to visually find the cracks until you pull the trans. I even used my borescope and couldn't see it. On a more positive note though, the parts are fairly cheap.

MikeyMan · 04-01-2012, 03:46 AM

Maybe a bad motor mount? Inspect the fan shroud to see if the fan has rubbed it.

Nova_Cobra64 · 04-01-2012, 09:02 AM

I've experienced something similar in the past, turned out to be loose torque converter bolts.
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**jocko** · 04-01-2012, 09:32 AM

is it getting louder as time goes by? (hate to suggest a rod bearing...) Hopefully not.

Lee H · 04-01-2012, 11:19 AM

U Joints?

RexDodge · 04-01-2012, 11:25 AM

Quote:

Originally Posted by MikeyMan

Maybe a bad motor mount? Inspect the fan shroud to see if the fan has rubbed it.

I think Mikey got it! I'd have to vote motor mounts too...

sanford66 · 04-01-2012, 11:33 AM

Quote:

Originally Posted by hotrod100

Check for a broken flex plate. I just got done replacing one in a Suburban that was doing the exact same thing. It ended up having two small cracks around the mounting bolts and wouldn't make any noise until you got on it a bit then it would start snapping and popping. We really heard it when we were towing the boat! Unfortunately you may not be able to visually find the cracks until you pull the trans. I even used my borescope and couldn't see it. On a more positive note though, the parts are fairly cheap.

X2 on this theory. When the flexplate is cracked it will make a lot of clatter and racket sometimes. Also the sounds can change with the RPM. Joseph

Critter · 04-01-2012, 01:06 PM

I'm in the broken flex plate crowd, had them do weird things before. Also the torque converter bolts as mentioned, either way still need to look at the same area of the truck.

05crewcab · 04-01-2012, 06:44 PM

Flexplate might make sense. I took the fan shroud out to make sure and it still does it. Here is a quick video I took this afternoon. (sorry for the poor camera skills)

http://youtu.be/n4gX-dlJxVk?t=1m

FLEET72 · 04-01-2012, 09:56 PM

Tried to look but all I got was:

Quote:

This video is unavailable
This video is private.
Sorry about that.

05crewcab · 04-01-2012, 10:18 PM

whoops... here is the correct link:

Old Truck Clatterin down the road. - YouTube

old Chevy guy · 04-01-2012, 10:32 PM

Sounds rough,whats the oil preasure look like when it does that? Is the presure good overall? Seems like mostly under a load,is that right? Does it get worse as it gets hotter?

05crewcab · 04-01-2012, 10:49 PM

Overall oil pressure seems fine, and I have only driven it far enough to get to operating temp, but i would say it does get more consistent as the truck warms.

jsbgump · 04-01-2012, 11:02 PM

You have a broken flywheel or loose torque converter bolts. I have had this problem serveral times on my 68 and that was the problem. You probably can't tell the flexplate is broken until it's unbolted

oldschool18 · 04-01-2012, 11:30 PM

Thats nothing like I thought you were talking about, i would go with the above and say flywheel-flex plate..........had a 76 camaro sounded kinda like that, missing one fly wheel bolt and the other two were loose

FLEET72 · 04-01-2012, 11:55 PM

I concur, the flexplate is where I would start looking.

05crewcab · 04-02-2012, 12:33 AM

I got real curious tonight after hearing a couple more yeh's for flywheel so I crawled under took a look. From the surface the flywheel looks pristine, so i checked the torque converter bolts. two were really tight, and the third i could turn maybe a 1/2 turn. I'll take the truck out tomorrow and see if this was the smoking gun. If not, I guess the flywheel comes out...

shawno72 · 04-02-2012, 12:52 AM

I got the same sound right now and I believe it to be the flex plate to.
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03-31-2012, 11:42 PM	#1
05crewcab Registered User Join Date: Mar 2010 Location: Minnetonka, MN Posts: 409	rattle rattle thunder clatter boom boom boom... Strange thing started happening this week... When my truck is moving and under load, (accelerating, driving up a hill, etc.) I have this rather loud clattering noise coming from someplace in or near the engine bay. It doesn't happen if I don't have my foot in it, and won't make the noise in Park. I crawled under the truck tonight and checked everywhere for things touching the drivetrain...exhaust hangers, trans cooler lines, kickdown cable, speedo cable, PS lines, loose brackets, starter, etc. I also checked and greased my u-joints and the carrier bearing is in good shape. Anyone have any ideas on what to check next? The motor sounds fine when revving in Park, and doesn't make this noise at idle or over 3000 RPM... I'm stumped. __________________ 1971 C-20 350/350

04-01-2012, 12:32 AM	#2
oldschool18 Registered User Join Date: Jan 2010 Location: Hollidaysburg, PA Posts: 785	Re: rattle rattle thunder clatter boom boom boom... does it seem to be missing when its doing this __________________ _________________________________ 62 Impala 70 C-10 LWB 71 K-10 SWB 85 C-10 LWB==SOLD 01 2500 HD Members Met......2003Silverado (Dave)

04-01-2012, 12:41 AM	#3
05crewcab Registered User Join Date: Mar 2010 Location: Minnetonka, MN Posts: 409	Re: rattle rattle thunder clatter boom boom boom... I don't think it is missing/stumbling, etc. the power seems normal as near as i can tell. __________________ 1971 C-20 350/350

04-01-2012, 12:42 AM	#4
steves1967 Registered User Join Date: Dec 2001 Location: Manteca, Ca USA Posts: 305	Re: rattle rattle thunder clatter boom boom boom... Detonation?? What's the engine timing? __________________ '71 Chevy 3/4 Ton Longbed '22 Chevy Tahoe RST '67 Firebird- 8 sec street car '24 GMC CC 4x4 Duramax Dually

04-01-2012, 12:45 AM	#5
oldschool18 Registered User Join Date: Jan 2010 Location: Hollidaysburg, PA Posts: 785	Re: rattle rattle thunder clatter boom boom boom... mine was doing that then it started to miss and it was a bad plug wire, and mine only did it when it was under a load....going up hill.....accelerating quick __________________ _________________________________ 62 Impala 70 C-10 LWB 71 K-10 SWB 85 C-10 LWB==SOLD 01 2500 HD Members Met......2003Silverado (Dave)

04-01-2012, 12:46 AM	#6
05crewcab Registered User Join Date: Mar 2010 Location: Minnetonka, MN Posts: 409	Re: rattle rattle thunder clatter boom boom boom... No idea what the timing is unfortunately...I haven't touched it since I bought it two years ago. __________________ 1971 C-20 350/350

04-01-2012, 02:47 AM	#8
hotrod100 Registered User Join Date: Aug 2009 Location: Bullhead City, AZ. Posts: 88	Re: rattle rattle thunder clatter boom boom boom... Check for a broken flex plate. I just got done replacing one in a Suburban that was doing the exact same thing. It ended up having two small cracks around the mounting bolts and wouldn't make any noise until you got on it a bit then it would start snapping and popping. We really heard it when we were towing the boat! Unfortunately you may not be able to visually find the cracks until you pull the trans. I even used my borescope and couldn't see it. On a more positive note though, the parts are fairly cheap. __________________ My build thread.

04-01-2012, 03:46 AM	#9
MikeyMan Registered User Join Date: May 2008 Location: S.W. Chicago, IL. Posts: 317	Re: rattle rattle thunder clatter boom boom boom... Maybe a bad motor mount? Inspect the fan shroud to see if the fan has rubbed it.

04-01-2012, 09:02 AM	#10
Nova_Cobra64 Registered User Join Date: Aug 2002 Location: Melville, SK Posts: 1,144	Re: rattle rattle thunder clatter boom boom boom... I've experienced something similar in the past, turned out to be loose torque converter bolts. Posted via Mobile Device __________________ 2004 Silverado - Beater 1969 GMC - In progress http://67-72chevytrucks.com/vboard/s...d.php?t=441683 2011 Aveo - Work commuter 2013 Crestliner Fish Hawk 1650 - The reason no work gets done on the project truck.

04-01-2012, 09:32 AM	#11
jocko Senior Member Join Date: Oct 2009 Location: Godley, TX Posts: 17,975	Re: rattle rattle thunder clatter boom boom boom... is it getting louder as time goes by? (hate to suggest a rod bearing...) Hopefully not.

04-01-2012, 11:19 AM	#12
Lee H Registered User Join Date: Jun 2010 Location: Upland Ca Posts: 4,147	Re: rattle rattle thunder clatter boom boom boom... U Joints? __________________ 1972 C10 SWB, Air, PS, PB, 350/350THM. Second owner. 1965 Corvette roadster, 44K miles, 327/365 SHP, 4 speed, side exhaust, knockoffs, teak, second owner (bought in 1970), Have ALL numbers matching components. My frame off restoration thread: http://67-72chevytrucks.com/vboard/s...d.php?t=556703

04-01-2012, 01:06 PM	#15
Critter Future TOTM Winner Join Date: Aug 2006 Location: Bulverde, TX Posts: 2,692	Re: rattle rattle thunder clatter boom boom boom... I'm in the broken flex plate crowd, had them do weird things before. Also the torque converter bolts as mentioned, either way still need to look at the same area of the truck. __________________ 72 Chevy CST K5 HIGHLANDER BLAZER Getting a 6.0,NV4500,NP205,14BFF (Currently laying all over the place in little pieces) 72 Chevy swb step-side "LS" 6.0 Here's a build thread of sorts 2002 HD2500 Crew Cab, 8.1L Allison 4x4 Daily Driver Check it out www.lsdyno.com

04-01-2012, 06:44 PM	#16
05crewcab Registered User Join Date: Mar 2010 Location: Minnetonka, MN Posts: 409	Re: rattle rattle thunder clatter boom boom boom... Flexplate might make sense. I took the fan shroud out to make sure and it still does it. Here is a quick video I took this afternoon. (sorry for the poor camera skills) http://youtu.be/n4gX-dlJxVk?t=1m __________________ 1971 C-20 350/350

04-01-2012, 10:32 PM	#19
old Chevy guy Registered User Join Date: Apr 2007 Location: Foster Rhode Island Posts: 1,176	Re: rattle rattle thunder clatter boom boom boom... Sounds rough,whats the oil preasure look like when it does that? Is the presure good overall? Seems like mostly under a load,is that right? Does it get worse as it gets hotter?

04-01-2012, 10:49 PM	#20
05crewcab Registered User Join Date: Mar 2010 Location: Minnetonka, MN Posts: 409	Re: rattle rattle thunder clatter boom boom boom... Overall oil pressure seems fine, and I have only driven it far enough to get to operating temp, but i would say it does get more consistent as the truck warms. __________________ 1971 C-20 350/350



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04-01-2012, 11:02 PM	#21
jsbgump Gone Fishing Join Date: Aug 2005 Location: Fort Worth, Texas 76135 Posts: 12,361	Re: rattle rattle thunder clatter boom boom boom... You have a broken flywheel or loose torque converter bolts. I have had this problem serveral times on my 68 and that was the problem. You probably can't tell the flexplate is broken until it's unbolted __________________ 68 Chevy Short Fleetside LSX Swap Under Way 3.73 posi 2.5/4 drop Frame of resto has been started 2022 Hyundai Tucson Limited 2019 Chevy Traverse Redline Edition Wifes Ride Build Thread http://67-72chevytrucks.com/vboard/s...=1#post3483616

04-01-2012, 11:30 PM	#22
oldschool18 Registered User Join Date: Jan 2010 Location: Hollidaysburg, PA Posts: 785	Re: rattle rattle thunder clatter boom boom boom... Thats nothing like I thought you were talking about, i would go with the above and say flywheel-flex plate..........had a 76 camaro sounded kinda like that, missing one fly wheel bolt and the other two were loose __________________ _________________________________ 62 Impala 70 C-10 LWB 71 K-10 SWB 85 C-10 LWB==SOLD 01 2500 HD Members Met......2003Silverado (Dave)

04-01-2012, 11:55 PM	#23
FLEET72 Registered User Join Date: Jan 2007 Location: Sonoma, CA Posts: 521	Re: rattle rattle thunder clatter boom boom boom... I concur, the flexplate is where I would start looking. __________________ Oscar '72 Shortbed Fleetside '95 Jimmy 4X4 '69 GMC Custom Camper

04-02-2012, 12:33 AM	#24
05crewcab Registered User Join Date: Mar 2010 Location: Minnetonka, MN Posts: 409	Re: rattle rattle thunder clatter boom boom boom... I got real curious tonight after hearing a couple more yeh's for flywheel so I crawled under took a look. From the surface the flywheel looks pristine, so i checked the torque converter bolts. two were really tight, and the third i could turn maybe a 1/2 turn. I'll take the truck out tomorrow and see if this was the smoking gun. If not, I guess the flywheel comes out... __________________ 1971 C-20 350/350

04-02-2012, 12:52 AM	#25
shawno72 C/10 junkie Join Date: Nov 2010 Location: Stockton Ca Posts: 9,093	Re: rattle rattle thunder clatter boom boom boom... I got the same sound right now and I believe it to be the flex plate to. Posted via Mobile Device __________________ Shawn 70 LWB C10 current driver/project http://67-72chevytrucks.com/vboard/s...d.php?t=663051 68 SWB C10 Work in progress.....SOLD http://67-72chevytrucks.com/vboard/s...d.php?t=559520 72 LWB C10 Sold 71 LWB C10 Sold 68 LWB C10 CST Sold http://youtu.be/kbB0QrBIs9k My mom always had the best advice. It was just a tad late. After a fall that involved blood, she'd say....."Careful!"

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