Filler neck Checkvalve? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

custom10nut · 03-12-2018, 05:44 PM

I searched couldn't find any other threads, so maybe I have the wrong terminology.
Is there such a thing as an insert, to go into the filler neck, to prevent the gas from sloshing out on a Righthand turn, when the tank is full?
All newer vehicles were equipped with the trapdoor the the pump nozzle goes into.
I'm thinking about fabricating an insert, but haven't figured out how to secure it
(No, I'm not going to try to weld it

)
Some will say "Just relocate the tank", but I want to leave it in the cab.
Back to my original question.
Is there a vendor that makes/sells an insert like this?
Thanks in advance

*randy500* · 03-12-2018, 07:00 PM

I use a gas cap and it works pretty well.

**Steeveedee** · 03-12-2018, 08:50 PM

The correct gas cap avoids this problem. If you make a right turn, it takes enough time for fuel to slosh that a trap door isn't going to help, especially, iirc, there are vent holes in the rest of the reducer in the neck for vapors to be pulled back into the vapor recovery hose. Maybe you don't have those fuel nozzles where you live- they are mostly used in high pollution areas.

custom10nut · 03-12-2018, 10:08 PM

I had several different types. The one that works best is the Standard Stainless vented cap (Stant), but it will still leak some on a right turn with the tank full.
The only one I've ever had that didn't leak was not vented, so in the end I couldn't use it.
I didn't mention before that my truck is a 70, so I need the vented cap.
I guess the reason this is now going to be an issue is that I'm about to start prepping to paint my truck, and I don't want to ruin a new paint job.

**jocko** · 03-12-2018, 10:21 PM

Yes, it's a frustrating problem - I've only had one truck do it and the only semi-solution was to replace the cap(s) until one sealed better than the rest. Kinda frustrating. Luckily I wasn't concerned with paint just yet, but the smell about asphyxiated me... So I only turned left from then on.

**Boog** · 03-12-2018, 11:03 PM

Turn left, go fast. The life of a stock car racer. Yeah buddy!

RichardJ · 03-12-2018, 11:27 PM

Are you in the habit of clicking away on the nozzle after it first shuts itself off?

Warrens69GMC · 03-13-2018, 01:00 AM

maybe an anti siphon device?

custom10nut · 03-13-2018, 08:12 PM

Quote:

Originally Posted by Warrens69GMC

maybe an anti siphon device?

Will this fit into my filler neck? And where could I get one?

1968aj · 03-13-2018, 09:24 PM

I never fill mine up all the way.

custom10nut · 03-13-2018, 10:11 PM

Quote:

Originally Posted by 1968aj

I never fill mine up all the way.

I agree, and that's what I do, most of the time. But I'm are I'm not the only one who has this issue, and that the factory didn't have this flaw identified. It's most likely why they went with the vented tank in '71-72

697498chevy · 03-14-2018, 05:29 AM

Have you tried a Car Quest #10623 ? It works well on my 1969 C 10 . I did replace the gas tank a while back though .

**special-K** · 03-14-2018, 06:36 AM

A cap has to be pretty lousy to let gas leak out making turns. A sure sign a better cap is needed. I've had them get bad to where they will leak when parked with the left side down when I had just filled up. And that is usually once it sat a while, like when it is hot and needs vented

Keystone_Hate · 03-14-2018, 09:42 AM

Mine leaks also on my 72. Interesting note, I found that the rubber gasket for the gas cap is the same size as the one on the gas tank of my 1960 Harley Panhead. So I grabbed one of those from the Harley dealership and it helped a bunch. I think a vented gas cap is going to leak a little bit no matter what, just by it's design. Unless possibly there is one made that has a spring type check valve almost like a thermostat to let pressure seep out but not be completely open all the time.

03-12-2018, 07:00 PM	#2
randy500 Account Suspended Join Date: Jul 2016 Location: Tacoma, WA Posts: 6,873	Re: Filler neck Checkvalve? I use a gas cap and it works pretty well.

03-12-2018, 08:50 PM	#3
Steeveedee Who Changed This? Join Date: Jan 2013 Location: Simi Valley, CA Posts: 10,610	Re: Filler neck Checkvalve? The correct gas cap avoids this problem. If you make a right turn, it takes enough time for fuel to slosh that a trap door isn't going to help, especially, iirc, there are vent holes in the rest of the reducer in the neck for vapors to be pulled back into the vapor recovery hose. Maybe you don't have those fuel nozzles where you live- they are mostly used in high pollution areas. __________________ ~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA

03-12-2018, 10:08 PM	#4
custom10nut Registered User Join Date: Apr 2015 Location: East Tn (In the heart of the Smoky Mtns) Posts: 1,882	Re: Filler neck Checkvalve? I had several different types. The one that works best is the Standard Stainless vented cap (Stant), but it will still leak some on a right turn with the tank full. The only one I've ever had that didn't leak was not vented, so in the end I couldn't use it. I didn't mention before that my truck is a 70, so I need the vented cap. I guess the reason this is now going to be an issue is that I'm about to start prepping to paint my truck, and I don't want to ruin a new paint job.

03-12-2018, 10:21 PM	#5
jocko Senior Member Join Date: Oct 2009 Location: Godley, TX Posts: 17,976	Re: Filler neck Checkvalve? Yes, it's a frustrating problem - I've only had one truck do it and the only semi-solution was to replace the cap(s) until one sealed better than the rest. Kinda frustrating. Luckily I wasn't concerned with paint just yet, but the smell about asphyxiated me... So I only turned left from then on.

03-12-2018, 11:03 PM	#6
Boog laying low Join Date: Mar 2001 Location: Searcy, Ark. USA Posts: 13,459	Re: Filler neck Checkvalve? Turn left, go fast. The life of a stock car racer. Yeah buddy! __________________ Boog 69 Chevy stepside, 358/T350, 4.11 posi, 4.5/4 drop, rallys, poboy driver primer is finer 91 Chevy sportside, Tahoe, Yukon & GMC Crewcab All GM..'nuff said. I stand for the flag and kneel at the cross

03-12-2018, 05:44 PM	#1
custom10nut Registered User Join Date: Apr 2015 Location: East Tn (In the heart of the Smoky Mtns) Posts: 1,882	Filler neck Checkvalve? I searched couldn't find any other threads, so maybe I have the wrong terminology. Is there such a thing as an insert, to go into the filler neck, to prevent the gas from sloshing out on a Righthand turn, when the tank is full? All newer vehicles were equipped with the trapdoor the the pump nozzle goes into. I'm thinking about fabricating an insert, but haven't figured out how to secure it (No, I'm not going to try to weld it) Some will say "Just relocate the tank", but I want to leave it in the cab. Back to my original question. Is there a vendor that makes/sells an insert like this? Thanks in advance

03-12-2018, 11:27 PM	#7
RichardJ Registered User Join Date: Apr 2010 Location: So Cal Posts: 1,460	Re: Filler neck Checkvalve? Are you in the habit of clicking away on the nozzle after it first shuts itself off? __________________ '67 GMC 2500, 292, 4spd, AC

03-13-2018, 01:00 AM	#8
Warrens69GMC Registered User Join Date: Jan 2003 Location: Safford,AZ Posts: 3,612	Re: Filler neck Checkvalve? maybe an anti siphon device? Attached Images

03-13-2018, 09:24 PM	#10
1968aj Registered User Join Date: Apr 2009 Location: houston texas Posts: 1,438	Re: Filler neck Checkvalve? I never fill mine up all the way.

03-14-2018, 05:29 AM	#12
697498chevy Registered User Join Date: Jan 2009 Location: South Carolina Posts: 265	Re: Filler neck Checkvalve? Have you tried a Car Quest #10623 ? It works well on my 1969 C 10 . I did replace the gas tank a while back though .

03-14-2018, 06:36 AM	#13
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,852	Re: Filler neck Checkvalve? A cap has to be pretty lousy to let gas leak out making turns. A sure sign a better cap is needed. I've had them get bad to where they will leak when parked with the left side down when I had just filled up. And that is usually once it sat a while, like when it is hot and needs vented __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~

03-14-2018, 09:42 AM	#14
Keystone_Hate Registered User Join Date: Apr 2017 Location: Colorado Springs Posts: 129	Re: Filler neck Checkvalve? Mine leaks also on my 72. Interesting note, I found that the rubber gasket for the gas cap is the same size as the one on the gas tank of my 1960 Harley Panhead. So I grabbed one of those from the Harley dealership and it helped a bunch. I think a vented gas cap is going to leak a little bit no matter what, just by it's design. Unless possibly there is one made that has a spring type check valve almost like a thermostat to let pressure seep out but not be completely open all the time.



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