something rattling under hood or dash under load - The 1947 - Present Chevrolet & GMC Truck Message Board Network

vardenafil · 10-23-2023, 03:12 PM

i have a noise that i cant seem to find where it coming from. if truck is idling it sounds normal. if i give it a little gas once the rpms jump over 2000 rpms? it starts to rattle real loud. it almost sounds like its coming from under the dash but there is nothing there except for the ac plumbing but the ac compressor is not hooked up. the belt is disconnected under the hood to the ac unit. what would cause a real loud rattle under load at operating rpms? is this timing related? i dont know what pinging or knocking sounds like.

**Steeveedee** · 10-23-2023, 05:37 PM

Can you make a recording?

vardenafil · 10-23-2023, 07:46 PM

Sure can. I’ll see if I can post one up today or tomorrow

body bolt · 10-24-2023, 11:04 AM

Have you run it up to 2K by hand with the hood open?

**1970 CST Short Wide** · 10-24-2023, 11:30 AM

If it’s an automatic you could have a cracked Flex Plate. Almost sounds like a Rod knock

**Jason Banks** · 10-24-2023, 06:20 PM

Quote:

Originally Posted by 1970 CST Short Wide

If it’s an automatic you could have a cracked Flex Plate. Almost sounds like a Rod knock

I'd put my money on this being the problem...based on the info we have so far...

MS66 · 10-25-2023, 08:33 AM

Quote:

Originally Posted by 1970 CST Short Wide

If it’s an automatic you could have a cracked Flex Plate. Almost sounds like a Rod knock

^^^ this. Have seen this more than a few times. Pretty unnerving the first time you experience it.

vardenafil · 10-26-2023, 09:45 PM

Sorry I canÂ’t figure out how to upload audio or video to the site. It keeps erroring out.

**Rust_never_sleeps** · 10-26-2023, 09:54 PM

Quote:

Originally Posted by vardenafil

Sorry I canÂ’t figure out how to upload audio or video to the site. It keeps erroring out.

might only be possible as a zipped file, based on the list of types allowed

**dmjlambert** · 10-26-2023, 10:36 PM

Quote:

Originally Posted by vardenafil

Sorry I canÂ’t figure out how to upload audio or video to the site. It keeps erroring out.

The easiest is to publish the video to youtube. Then give us the link to the video.

**68bowtie** · 10-26-2023, 10:39 PM

Post it on rumble

vardenafil · 10-28-2023, 07:55 PM

https://rumble.com/v3sc5sl-c10-rattle.html

ok i think i got it figured out. the noise seems much more pronounced in person. but you can kinda hear it on the video

**Steeveedee** · 10-28-2023, 09:59 PM

OK, that's at least not a rod bearing(?) or a cracked flex plate- it being a stick shift, and it doesn't sound like detonation to me. I think that I'd have to be there in person to figure this one out. All I'm hearing is kind of a squeak.

**1970 CST Short Wide** · 10-28-2023, 10:16 PM

Quote:

Originally Posted by Steeveedee

OK, that's at least not a rod bearing(?) or a cracked flex plate- it being a stick shift, and it doesn't sound like detonation to me. I think that I'd have to be there in person to figure this one out. All I'm hearing is kind of a squeak.

That shifter sure looks like it’s automatic. Can the owner Please confirm Auto or Manual

vardenafil · 10-29-2023, 03:34 PM

The truck has a 700r4 auto transmission. It was originally a stick but previous owner swapped the transmission l.

**1970 CST Short Wide** · 10-29-2023, 04:13 PM

Remove the inspection plate , if there is one, and look at the flywheel turn it by hand and look for cracks. Also tap on it with a wrench and listen to it to see if it’s sounds solid
If all checks good you can rule it out. I can’t tell listing to your recording

**Steeveedee** · 10-29-2023, 06:12 PM

Quote:

Originally Posted by 1970 CST Short Wide

That shifter sure looks like it’s automatic. Can the owner Please confirm Auto or Manual

Guess I need to get my eyes checked.

**71CHEVYSHORTBED402** · 10-31-2023, 02:19 AM

By chance could it be a motor mount?

10-23-2023, 03:12 PM	#1
vardenafil Registered User Join Date: Oct 2020 Location: ca Posts: 106	something rattling under hood or dash under load i have a noise that i cant seem to find where it coming from. if truck is idling it sounds normal. if i give it a little gas once the rpms jump over 2000 rpms? it starts to rattle real loud. it almost sounds like its coming from under the dash but there is nothing there except for the ac plumbing but the ac compressor is not hooked up. the belt is disconnected under the hood to the ac unit. what would cause a real loud rattle under load at operating rpms? is this timing related? i dont know what pinging or knocking sounds like.

10-23-2023, 05:37 PM	#2
Steeveedee Who Changed This? Join Date: Jan 2013 Location: Simi Valley, CA Posts: 10,723	Re: something rattling under hood or dash under load Can you make a recording? __________________ ~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA

10-23-2023, 07:46 PM	#3
vardenafil Registered User Join Date: Oct 2020 Location: ca Posts: 106	Re: something rattling under hood or dash under load Sure can. I’ll see if I can post one up today or tomorrow

10-24-2023, 11:04 AM	#4
body bolt Registered User Join Date: Oct 2020 Location: Albuquerque, New Mexico Posts: 474	Re: something rattling under hood or dash under load Have you run it up to 2K by hand with the hood open?

10-24-2023, 11:30 AM	#5
1970 CST Short Wide Senior Moment Join Date: Mar 2002 Location: Pittsburg Ca Posts: 4,192	Re: something rattling under hood or dash under load If it’s an automatic you could have a cracked Flex Plate. Almost sounds like a Rod knock __________________ 1970 CST LS 1 6 speed Ford 9 inch Detroit Tru Track, Dakota Didgital, Vintage Air, QA1 Coil Overs Front & Rear Lots of FUN 2013 GMC PU, Oldest Son 71 GMC LWB. QA1 Suspension, Angry SB. Youngest Son 2017 Toyota SUV Daughters car 2018 Traverse , Wife’s Ride Pittsburg Ca 94565

10-26-2023, 09:45 PM	#8
vardenafil Registered User Join Date: Oct 2020 Location: ca Posts: 106	Re: something rattling under hood or dash under load Sorry I canÂ’t figure out how to upload audio or video to the site. It keeps erroring out.

10-26-2023, 10:39 PM	#11
68bowtie Senior Member Join Date: Jan 2007 Location: Turlock, CA Posts: 8,801	Re: something rattling under hood or dash under load Post it on rumble __________________ Please help my sister in law with her battle with cancer https://gofund.me/902f6fce Thank you all so far you are angels!! Project "C10 Fever" (68 factory black 396 swb) Project "Little Sister" (70 c10 blue original paint refresh) Project "Blue Bomb" (70 c30 blue original paint refresh) SOLD Project "Vitamin C" (71 c10 orange original paint refresh) SOLD

10-28-2023, 07:55 PM	#12
vardenafil Registered User Join Date: Oct 2020 Location: ca Posts: 106	Re: something rattling under hood or dash under load https://rumble.com/v3sc5sl-c10-rattle.html ok i think i got it figured out. the noise seems much more pronounced in person. but you can kinda hear it on the video

10-28-2023, 09:59 PM	#13
Steeveedee Who Changed This? Join Date: Jan 2013 Location: Simi Valley, CA Posts: 10,723	Re: something rattling under hood or dash under load OK, that's at least not a rod bearing(?) or a cracked flex plate- it being a stick shift, and it doesn't sound like detonation to me. I think that I'd have to be there in person to figure this one out. All I'm hearing is kind of a squeak. __________________ ~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA

10-29-2023, 03:34 PM	#15
vardenafil Registered User Join Date: Oct 2020 Location: ca Posts: 106	Re: something rattling under hood or dash under load The truck has a 700r4 auto transmission. It was originally a stick but previous owner swapped the transmission l.

10-29-2023, 04:13 PM	#16
1970 CST Short Wide Senior Moment Join Date: Mar 2002 Location: Pittsburg Ca Posts: 4,192	Re: something rattling under hood or dash under load Remove the inspection plate , if there is one, and look at the flywheel turn it by hand and look for cracks. Also tap on it with a wrench and listen to it to see if it’s sounds solid If all checks good you can rule it out. I can’t tell listing to your recording __________________ 1970 CST LS 1 6 speed Ford 9 inch Detroit Tru Track, Dakota Didgital, Vintage Air, QA1 Coil Overs Front & Rear Lots of FUN 2013 GMC PU, Oldest Son 71 GMC LWB. QA1 Suspension, Angry SB. Youngest Son 2017 Toyota SUV Daughters car 2018 Traverse , Wife’s Ride Pittsburg Ca 94565

10-31-2023, 02:19 AM	#18
71CHEVYSHORTBED402 Senior Member Join Date: Feb 2009 Location: Northern Nevada Posts: 7,325	Re: something rattling under hood or dash under load By chance could it be a motor mount? __________________ Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assembly kit for restoring the (a) truck from the ground up. My build thread, and more on the assembly kit https://67-72chevytrucks.com/vboard/...d.php?t=730025



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