gas leaking from cap? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

johnymac · 05-21-2003, 06:08 PM

I realize now not to park the truck on uneven ground after filling the tank, but want to ask if this is normal.

When ever I fill my gas tank in my 67 C10, not to the top, but close.
When I park on a sloped graded, low on the filler side, it leaks. It leaves a big puddle, not to mention the gas makes a mess down the corner of the cab.

I have tighted the cap and learned not to park this way.
I am curious if this is normal, or do I have some kind of pressure problem?

Thanks in advance to all that reply!!

**old Rusty C10** · 05-21-2003, 06:55 PM

ive never heard of that happening before have ya checked to make sure the vent lines arent blocked other than that id say get another fuel cap

mrein3 · 05-21-2003, 08:15 PM

I'm not 100% positive but I believe all but 1972 trucks have tanks that are vented through the cap.

The same thing will happen (leak) if you fill it full then park it in the sun on a hot day.

aesj2 · 05-21-2003, 09:01 PM

The vent is in the cab in the pass side "B" post, and vent is from the evap canister.

DevinM · 05-21-2003, 09:44 PM

My cheap alternative is to take a piece of saranwrap and fold it a few times, cover the hole, and tighten the cap. Worked for me!

gmc67swb · 05-21-2003, 10:11 PM

MAKE SURE THE RUBBER INSIDE THE CAP ISN'T DRY ROTTED. IF THAT IS OK MAKE SURE YOU HAVE THE RIGHT CAP. I GOT ONE FROM AUTO ZONE AND IT WENT ON BUT DID NOT SEAL FOR SH#T. I WOULD START THERE.

Big69C20 Toy · 05-21-2003, 11:23 PM

i had the same problem with my 69 that and the previous owners banged up the filler neck a bit. I just ripped out the old rubber seal and put in a thicker new one... was kinda tough to seat at first but seals great. i think i picked up 1/4" rubber sealant from the hardware store that was setup for chemical resistance

Lippyp · 05-22-2003, 05:41 AM

The seal on my cap had gone porous, it was fine immeadiately after filling up but after a while of cornering it would start to leak. The seal by this point had soaked up so much gas it started to leak out. New cap solved the problem.

powder · 05-22-2003, 07:27 AM

i had that problem to put a new gas cap on then took the old gasket of the other one and put it on top of the new one

05-21-2003, 06:08 PM	#1
johnymac Registered User Join Date: Mar 2001 Location: Dover, NH USA Posts: 194	gas leaking from cap? I realize now not to park the truck on uneven ground after filling the tank, but want to ask if this is normal. When ever I fill my gas tank in my 67 C10, not to the top, but close. When I park on a sloped graded, low on the filler side, it leaks. It leaves a big puddle, not to mention the gas makes a mess down the corner of the cab. I have tighted the cap and learned not to park this way. I am curious if this is normal, or do I have some kind of pressure problem? Thanks in advance to all that reply!! Last edited by johnymac; 05-21-2003 at 06:12 PM.

05-21-2003, 06:55 PM	#2
old Rusty C10 Robert Olson Transport Join Date: Oct 2002 Location: recent transplant to NC USA Posts: 20,310	ive never heard of that happening before have ya checked to make sure the vent lines arent blocked other than that id say get another fuel cap __________________ 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!!

05-21-2003, 08:15 PM	#3
mrein3 Registered User Join Date: Feb 2000 Location: Center City, MN, USA Posts: 3,254	I'm not 100% positive but I believe all but 1972 trucks have tanks that are vented through the cap. The same thing will happen (leak) if you fill it full then park it in the sun on a hot day. __________________ '70 cab, '71 chassis, 383, TH350, NP205. '71 Malibu convertible '72 Malibu hard top Center City, MN

05-21-2003, 09:44 PM	#5
DevinM Registered User Join Date: Jan 2002 Location: Deerfield, MA USA Posts: 198	My cheap alternative is to take a piece of saranwrap and fold it a few times, cover the hole, and tighten the cap. Worked for me! __________________ '71 Chevy C-10 - Current '62 Imapla SS - Traded for my current '73 Nova Hatch - traded for ATC-350X '73 Chevelle Deluxe - First car (R.I.P) DEERFIELD, MA

05-21-2003, 10:11 PM	#6
gmc67swb Registered User Join Date: Feb 2003 Location: Mesquite, Tx Posts: 396	MAKE SURE THE RUBBER INSIDE THE CAP ISN'T DRY ROTTED. IF THAT IS OK MAKE SURE YOU HAVE THE RIGHT CAP. I GOT ONE FROM AUTO ZONE AND IT WENT ON BUT DID NOT SEAL FOR SH#T. I WOULD START THERE. __________________ GM 330HP/350, Magnuson 122HH, Tremec TKO 5spd

05-21-2003, 09:01 PM	#4
aesj2 Registered User Join Date: Feb 2002 Location: Ferndale, Michigan, USA Posts: 94	The vent is in the cab in the pass side "B" post, and vent is from the evap canister.

05-21-2003, 11:23 PM	#7
Big69C20 Toy Livin' it up. Join Date: Nov 2001 Location: Richland, MI Posts: 2,212	i had the same problem with my 69 that and the previous owners banged up the filler neck a bit. I just ripped out the old rubber seal and put in a thicker new one... was kinda tough to seat at first but seals great. i think i picked up 1/4" rubber sealant from the hardware store that was setup for chemical resistance __________________ -Greg; Sold the 69 C20. It's off to a better home with more love! Now onto the 86 CUCV M1009; K5 blazer with 6.2L diesel, corp 10 bolt axles, Detroit locker in the rear, trutrac front, 3.73 gears, 35" tires.

05-22-2003, 05:41 AM	#8
Lippyp English Chevy Owner Join Date: May 2002 Location: Shropshire, UK/ Lot, France Posts: 1,848	The seal on my cap had gone porous, it was fine immeadiately after filling up but after a while of cornering it would start to leak. The seal by this point had soaked up so much gas it started to leak out. New cap solved the problem. __________________ Phil '67 C10 long fleet. 350/TH350, 4 bbl Carter, K&N, Dual exhaust, loads of stuff coming soon 2001 S10 Blazer Daily Driver, bone stock 4 door 4x4 with manual transmission

05-22-2003, 07:27 AM	#9
powder the ring around my finger Join Date: Nov 2002 Location: Spring Lake NC Posts: 187	i had that problem to put a new gas cap on then took the old gasket of the other one and put it on top of the new one



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