Mystery gas tank noise - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Morgsie · 01-10-2007, 01:37 AM

Hey guys, I got a buddy who recently bought a '67 GMC 920. The truck runs alright, however there is a noise which is bugging the hell out of him. I believe this mystery noise is comming from the gas tank. Basically when you turn corners (usually the faster you're going and the tighter the corner the more audible the sound) you can hear something go from one end of the cab to the other. I've only heard the noise when the tank is near empty, but he says it does it even when full. Now I have a couple of questions:

1. Is there a baffel in the tank. If so, could it brake off and be causing this noise.
2. The gas gauge does work, which would lead me to believe that float has not broken off and floating around.
3. Has any one had or heard of this problem before.

Another buddy of mine owned an '88 GMC 1/2 ton which didn't have a working fuel gauge didn't work. He thought it was the actual gauge, so I tested it with a known good sending unit and the gauge worked fine. We dropped the tank to find that the baffel had separated from the tank and in the process took the float with it, so that's why I'm asking about the baffel. I personally think someone dropped a bolt or something into the tank, but who knows. Just wanted some input before we tear it out this weekend to see if there really is something in that damned tank!

Thanks,
morgsie

chopper103in · 01-10-2007, 02:15 AM

someone could of changed the sending unit before ------maybe an old float bouncing around

i know i have one loose in my tank

ClassicRedneck05 · 01-10-2007, 02:18 AM

that or old build up it the truck sat a while that or as well as someone stickin things down in it that could have been broken off or droped into it

Mudder · 01-10-2007, 04:51 AM

Take the tank out and look at the condition of the floor under and behind the tank.

72armyswbtruck · 01-10-2007, 06:34 AM

It might just be a hotwheels truck, when my brother took his out and had it treated and cleaned he found a Hotwheels car.

Mudder · 01-10-2007, 01:33 PM

It's most likely the floor has rusted along the back edge of the floor and the sound you hear is coming from inside the tank of the back wall of the truck and floor moving aginst each other. I dealt with the same thing several years ago with another cab after removing the tank probably 3 times to see what was in it.

Morgsie · 01-10-2007, 02:16 PM

I won't know until I check it. I wouldn't think the floor is rusted out, the rest of the truck is in surprisingly good shape. Cancer just starting to eat through on the drivers rocker. That doesn't mean that there isn't any other rust, but I'm still leaning towards that there is something in the tank. When it moves around it sounds like it's tumbling. Again, I won't know until I check it. I'll also make sure to post whatever I find. Thanks again guys.

-morgsie

PS: I guess I should ask, the tank looks fairly easy to take out. Bolts along the top, disconnect the fuel line and sending unit wire. Any other surprises to look forward to?

**chevy71super** · 01-10-2007, 04:18 PM

Mine did the exact same thing. When gas tank was close to empty something was rattling around when you went around a corner. When I rebuilt the truck and removed the gas tank and tipped it upside down out came the culprit . . . the center of a locking gas cap. Apparently someone punched it out at one time and let if fall into the tank.

jayharrell · 06-05-2008, 03:45 PM

Quote:

Originally Posted by chevy71super

Mine did the exact same thing. When gas tank was close to empty something was rattling around when you went around a corner. When I rebuilt the truck and removed the gas tank and tipped it upside down out came the culprit . . . the center of a locking gas cap. Apparently someone punched it out at one time and let if fall into the tank.

Same thing happend to me. But mine had just about all of the gas cap. It was clogging the pickup and causing realy wierd problems.

I recently rebuilt an old 3 wheeler that we had when i was a kid. I found some GI Joes in that tank. So thats where my borther was hiding my stuff......... LOL

c10addict · 06-05-2008, 05:26 PM

THe one in my 68 was full of gravel and sticks... Some little kind at one time was having fun doing magic tricks... Watch this stick disappear!

69lnghrn · 01-10-2007, 04:24 PM

my truck makes the same noise and its all my fault!!! i lost my gas cap key while working far from home. so i decided to take apart my gas cap i preceded by poping off the metal flange that holds the center core and there she went.. plop ,right into the tank ! oops
i went to auto zone bought a crappy cap put gas in it and im still driving it like that . i need to replace my tank anyways it has a hole on the top of it so i can never top it off.

Critter · 01-10-2007, 04:47 PM

You might get lucky with a long magnet. Could be worth a try before you pull the tank. Just cut a few doughnuts to the right so that everything will fly over to the left under the cap area.

toms68cst · 01-10-2007, 06:16 PM

Forgive me for stating the obvious but you can hear the gas itself sloshing around if the gas tank is about 1/2-3/4 full. Sometimes the gas in my truck really slaps the sides of the tank. If it's someone new to our trucks it may be unexpected.

Boise69 · 01-10-2007, 07:25 PM

I get a boom sometimes in my tank, scares the hell out of me. But then again just having that tank in the cab has me a bit nervous. But yea i get this.... boooom.... sometimes and i just figured its the gas moving around.

**John Fabris** · 01-10-2007, 09:37 PM

I am willing to bet that it is a broken gas nozzle from a gas pump... I have pulled several tanks and found gas nozzles, one tank had three of them in there!!!

FarmTruk · 01-10-2007, 10:17 PM

Quote:

Originally Posted by John Fabris

I am willing to bet that it is a broken gas nozzle from a gas pump... I have pulled several tanks and found gas nozzles, one tank had three of them in there!!!

BLACK AND BLUE 67-72 · 01-10-2007, 10:34 PM

I vote for pieces of an old locking cap being the source of the noise

7T2 K10 · 01-11-2007, 02:56 AM

Mine makes the same noise. But havent got around to finding out what it is. Please post up when you find out what it is.

oldpurple · 01-11-2007, 04:23 AM

As others have said, most likely just something in the tank.

Solution: stop going around corners

Morgsie · 01-13-2007, 09:02 PM

Mystery solved! Looks like chevy71super called it (see photo). Thanks again guys.

*rage'nrat638* · 01-13-2007, 09:19 PM

hey nice picture...glad you got'er done...
now let's see the rest of the truck

69lnghrn · 01-15-2007, 04:31 PM

Quote:

Originally Posted by Morgsie

Mystery solved! Looks like chevy71super called it (see photo). Thanks again guys.

ALRIGHT!!! THANKS FOR KEEPING UP WITH YOUR THREAD NOW I GOTTA GET MY CAP OUTTA MY TANK

Morgsie · 01-16-2007, 06:40 AM

It took me a little under 2 hours to do it. I pulled the seat (8 bolts), disconnected the fuel line, sender wire, unbolted the gas tank (10 bolts), pulled the gas tank out, poured remaining gas into a 5 gallon pale, almost filled up the pale. Thought the tank was empty, guess not, haha. The lock didn't fit through the filler neck, I had to grab onto it with a pair of pilers and then with a slot screw driver move the 2 locking tabs and it finally pulled through. Reinstalled everything, ran gas through a coffee filter and refilled the tank. If I were to do it again, I'd just put the seat forward and pull the sending unit out (which wouldn't require pulling out the seat or tank) and then fish around with a magnet, but hindsight is 20/20...

ghetto_superman · 01-16-2007, 02:39 PM

good thing about removing things from gas tank= theyre always nice and clean when they come out!

69lnghrn · 01-16-2007, 09:23 PM

<a href="http://photobucket.com/" target="_blank"><img src="http://i147.photobucket.com/albums/r316/lazquilon/DSCI0005-1.jpg" border="0" alt="Photobucket - Video and Image Hosting"></a> okay guys i think it took me longer to figure out how to post a damn picture, then it took to get my little buddy out the gas tank its been with me for awhile but its time for him to go in da trash !!

01-10-2007, 01:37 AM	#1
Morgsie Registered User Join Date: Apr 2005 Location: BC, Canada Posts: 122	Mystery gas tank noise Hey guys, I got a buddy who recently bought a '67 GMC 920. The truck runs alright, however there is a noise which is bugging the hell out of him. I believe this mystery noise is comming from the gas tank. Basically when you turn corners (usually the faster you're going and the tighter the corner the more audible the sound) you can hear something go from one end of the cab to the other. I've only heard the noise when the tank is near empty, but he says it does it even when full. Now I have a couple of questions: 1. Is there a baffel in the tank. If so, could it brake off and be causing this noise. 2. The gas gauge does work, which would lead me to believe that float has not broken off and floating around. 3. Has any one had or heard of this problem before. Another buddy of mine owned an '88 GMC 1/2 ton which didn't have a working fuel gauge didn't work. He thought it was the actual gauge, so I tested it with a known good sending unit and the gauge worked fine. We dropped the tank to find that the baffel had separated from the tank and in the process took the float with it, so that's why I'm asking about the baffel. I personally think someone dropped a bolt or something into the tank, but who knows. Just wanted some input before we tear it out this weekend to see if there really is something in that damned tank! Thanks, morgsie Last edited by Morgsie; 01-10-2007 at 01:38 AM.

01-10-2007, 02:15 AM	#2
chopper103in Registered User Join Date: Dec 2006 Location: sycamore,il Posts: 163	Re: Mystery gas tank noise someone could of changed the sending unit before ------maybe an old float bouncing around i know i have one loose in my tank

01-10-2007, 02:18 AM	#3
ClassicRedneck05 Senior Member Join Date: Dec 2005 Location: Humble, Texas Posts: 262	Re: Mystery gas tank noise that or old build up it the truck sat a while that or as well as someone stickin things down in it that could have been broken off or droped into it

01-10-2007, 04:51 AM	#4
Mudder Registered User Join Date: Feb 2001 Location: East Central, MO Posts: 11,336	Re: Mystery gas tank noise Take the tank out and look at the condition of the floor under and behind the tank.

01-10-2007, 06:34 AM	#5
72armyswbtruck Registered User Join Date: Feb 2004 Location: Idaho Posts: 4,033	Re: Mystery gas tank noise It might just be a hotwheels truck, when my brother took his out and had it treated and cleaned he found a Hotwheels car. __________________ "Remember, They can Kill You, but they can't eat You, That's against the law!!!!!!!!!"

01-10-2007, 01:33 PM	#6
Mudder Registered User Join Date: Feb 2001 Location: East Central, MO Posts: 11,336	Re: Mystery gas tank noise It's most likely the floor has rusted along the back edge of the floor and the sound you hear is coming from inside the tank of the back wall of the truck and floor moving aginst each other. I dealt with the same thing several years ago with another cab after removing the tank probably 3 times to see what was in it.

01-10-2007, 02:16 PM	#7
Morgsie Registered User Join Date: Apr 2005 Location: BC, Canada Posts: 122	Re: Mystery gas tank noise I won't know until I check it. I wouldn't think the floor is rusted out, the rest of the truck is in surprisingly good shape. Cancer just starting to eat through on the drivers rocker. That doesn't mean that there isn't any other rust, but I'm still leaning towards that there is something in the tank. When it moves around it sounds like it's tumbling. Again, I won't know until I check it. I'll also make sure to post whatever I find. Thanks again guys. -morgsie PS: I guess I should ask, the tank looks fairly easy to take out. Bolts along the top, disconnect the fuel line and sending unit wire. Any other surprises to look forward to? Last edited by Morgsie; 01-10-2007 at 02:18 PM.

01-10-2007, 04:18 PM	#8
chevy71super Registered User Join Date: Jan 2002 Location: So Cal Posts: 658	Re: Mystery gas tank noise Mine did the exact same thing. When gas tank was close to empty something was rattling around when you went around a corner. When I rebuilt the truck and removed the gas tank and tipped it upside down out came the culprit . . . the center of a locking gas cap. Apparently someone punched it out at one time and let if fall into the tank. __________________ 71 Cheyenne Super 4X4 SB 72 Cheyenne Super 4X4 SB 72 Cheyenne 4X4 SB

06-05-2008, 05:26 PM	#10
c10addict Registered User Join Date: Aug 2007 Location: pittsburgh pa Posts: 1,970	Re: Mystery gas tank noise THe one in my 68 was full of gravel and sticks... Some little kind at one time was having fun doing magic tricks... Watch this stick disappear! __________________ 68 C10 Shorty TPI,Bagged, and all the good stuff. Classic trucks feature June 06, On the cover of Jegs Christmas Catalog 08 67 C10 Shorty Shop truck project Bagged and Z'd under destruction and getting nowhere fast. 64 C10 Shop Truck/Daily driver, Bagged, Dropmember, SOLD!!!! Gone but not forgotten.. 54 GMC under the knife getting a S10 chassis swap and bagged. See my build thread... 07 GMC Sierra 5/7 drop, 22's and 24's Air ride on my mind.. http://67-72chevytrucks.com/vboard/s...d.php?t=339340 See pics of my trucks in my profile

01-10-2007, 04:24 PM	#11
69lnghrn whats a wrench Join Date: Dec 2006 Location: SAN DIEGO Posts: 139	Re: Mystery gas tank noise my truck makes the same noise and its all my fault!!! i lost my gas cap key while working far from home. so i decided to take apart my gas cap i preceded by poping off the metal flange that holds the center core and there she went.. plop ,right into the tank ! oops i went to auto zone bought a crappy cap put gas in it and im still driving it like that . i need to replace my tank anyways it has a hole on the top of it so i can never top it off.

01-10-2007, 04:47 PM	#12
Critter Future TOTM Winner Join Date: Aug 2006 Location: Bulverde, TX Posts: 2,692	Re: Mystery gas tank noise You might get lucky with a long magnet. Could be worth a try before you pull the tank. Just cut a few doughnuts to the right so that everything will fly over to the left under the cap area. __________________ 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

01-10-2007, 06:16 PM	#13
toms68cst Registered User Join Date: Jun 2000 Location: Bismarck, ND Posts: 4,300	Re: Mystery gas tank noise Forgive me for stating the obvious but you can hear the gas itself sloshing around if the gas tank is about 1/2-3/4 full. Sometimes the gas in my truck really slaps the sides of the tank. If it's someone new to our trucks it may be unexpected. __________________ Unrestored 68 C-10 CST. Original 327. 4-Speed CH465. 50k or so miles. TREASURER, Drum Brake Club.

01-10-2007, 07:25 PM	#14
Boise69 The Hammer Man Join Date: Oct 2006 Location: Wilmington, NC Posts: 864	Re: Mystery gas tank noise I get a boom sometimes in my tank, scares the hell out of me. But then again just having that tank in the cab has me a bit nervous. But yea i get this.... boooom.... sometimes and i just figured its the gas moving around. __________________ Boise69. Bought in Boise ID and its a '69 ___________________________________________ 1969 Chevy C-10 SWB 350/400 - drivable project www.americanhammer.com 2013 MBZ Sprinter customized 2005 MBZ Sprinter Van 2004 Land Rover Discovery 2001 Yamaha Road Star 1997 MBZ E420 1989 Ferrari Mondial T

01-10-2007, 09:37 PM	#15
John Fabris TOTY 2006 Join Date: Dec 1999 Location: Magalia CA USA Posts: 2,270	Re: Mystery gas tank noise I am willing to bet that it is a broken gas nozzle from a gas pump... I have pulled several tanks and found gas nozzles, one tank had three of them in there!!! __________________ John Fabris 67 C10 SWB

01-10-2007, 10:34 PM	#17
BLACK AND BLUE 67-72 Firefighter Join Date: Feb 2001 Location: Yellville, Ar, USA Posts: 1,943	Re: Mystery gas tank noise I vote for pieces of an old locking cap being the source of the noise __________________ '72 Chevy SWB 350 Auto '67 GMC LWB 350 4 speed '70 Chevy 4x4 Stepside 350 Auto Yellville, Ar. USA



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01-11-2007, 02:56 AM	#18
7T2 K10 Registered User Join Date: Apr 2006 Location: Dover,Tn Posts: 21	Re: Mystery gas tank noise Mine makes the same noise. But havent got around to finding out what it is. Please post up when you find out what it is.

01-11-2007, 04:23 AM	#19
oldpurple Registered User Join Date: Feb 2005 Location: Saskatoon, SK Posts: 97	Re: Mystery gas tank noise As others have said, most likely just something in the tank. Solution: stop going around corners

01-13-2007, 09:02 PM	#20
Morgsie Registered User Join Date: Apr 2005 Location: BC, Canada Posts: 122	Re: Mystery gas tank noise Mystery solved! Looks like chevy71super called it (see photo). Thanks again guys. Last edited by Morgsie; 01-13-2007 at 09:04 PM.

01-13-2007, 09:19 PM	#21
rage'nrat638 Account Suspended Join Date: Mar 2003 Location: THE FALL GUY CHICAGO IL Posts: 5,883	Re: Mystery gas tank noise hey nice picture...glad you got'er done... now let's see the rest of the truck

01-16-2007, 06:40 AM	#23
Morgsie Registered User Join Date: Apr 2005 Location: BC, Canada Posts: 122	Re: Mystery gas tank noise It took me a little under 2 hours to do it. I pulled the seat (8 bolts), disconnected the fuel line, sender wire, unbolted the gas tank (10 bolts), pulled the gas tank out, poured remaining gas into a 5 gallon pale, almost filled up the pale. Thought the tank was empty, guess not, haha. The lock didn't fit through the filler neck, I had to grab onto it with a pair of pilers and then with a slot screw driver move the 2 locking tabs and it finally pulled through. Reinstalled everything, ran gas through a coffee filter and refilled the tank. If I were to do it again, I'd just put the seat forward and pull the sending unit out (which wouldn't require pulling out the seat or tank) and then fish around with a magnet, but hindsight is 20/20...

01-16-2007, 02:39 PM	#24
ghetto_superman Registered User Join Date: Sep 2006 Location: Omaha, NE Posts: 1,982	Re: Mystery gas tank noise good thing about removing things from gas tank= theyre always nice and clean when they come out! __________________ -1947 3100 -1968 C10 -1970 K20

01-16-2007, 09:23 PM	#25
69lnghrn whats a wrench Join Date: Dec 2006 Location: SAN DIEGO Posts: 139	Re: Mystery gas tank noise <a href="http://photobucket.com/" target="_blank"><img src="http://i147.photobucket.com/albums/r316/lazquilon/DSCI0005-1.jpg" border="0" alt="Photobucket - Video and Image Hosting"></a> okay guys i think it took me longer to figure out how to post a damn picture, then it took to get my little buddy out the gas tank its been with me for awhile but its time for him to go in da trash !!

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