Schrader Valve Leaks Gas

[ViperTony]

I almost had a crispy Viper this past weekend on my way to an event. While cruising there was an overwhelming smell of gas. I pulled over and found that my schrader valve (valve on top of the intake manifold) was leaking gas. So much so that it began to pool in the engine block valley. The gas leak was not coming from where the valve threads into the block but rather from the valve tip. The leak was a steady stream of gas and not just a few drops. It's as if the valve tip was pressed in allowing gas to come through but it's not in that position. I was able to tighten the cap/cover enough to stop the leak and get back home.

However, this is the second schrader valve I've had issues with. My original valve did the same thing and I replaced it with a new one which is also ***** now. Any ideas/suggestions as to what might be causing this or am I just lucky enough to encounter two defective valves?

 

[99 R/T 10]

Isn't the valve just a normal air valve such as the cars tires use? The cap that goes on it should act as a secondary stop in case it fails. I guess just replace it again? What fuel pressure are you at Tony? I have never had a valve go bad.

Glad you caught it early

 

[AZTVR]

Isn't the valve just a normal air valve such as the cars tires use?

Good question. I'd be surprised that it would be, given the higher temperature and more chemically active environment.

Here is a product with a Schraeder valve with a Viton seal . http://www.dieselorings.com/schrader-valve-fuel-injection-rated-1-8-mnpt.html

I did look on their website and it says their cores on available with several different rubber types, although it does say in another place, "compatible with all fluids."

( This subject attracted my attention because my Dad worked at Schraeder, and there were often valve cores laying around the house while he was working on projects. )

 

[ViperTony]

Isn't the valve just a normal air valve such as the cars tires use? The cap that goes on it should act as a secondary stop in case it fails. I guess just replace it again? What fuel pressure are you at Tony? I have never had a valve go bad.

Glad you caught it early

To me, it looks just an ordinary tire valve stem obviously not rubber. I don't see a seal but I will take this one apart and post pics of what I find. I don't know what PSI I'm running as I haven't checked in a while but the last dyno I did I was at 55-58psi.

When I had my heads and intake ported by the great greg good I also had the intake powder coated. The powder-coater did not remove the valve. So *maybe* the powder-coating process/baking damaged the original valve causing it to leak. However, this valve is only 2 years old. Nothing was done to the intake that would cause the valve to leak. I just don't get it. If I run the engine with cap off the valve, its leaks gas. I'll order another one see what happens.

Yeah, I'm glad I caught it early because had the leak run down the other side of the intake towards the valve cover/headers....ouch. I'm happy that that valve is oriented on the inside of the intake.

 

[ViperTony]

Good question. I'd be surprised that it would be, given the higher temperature and more chemically active environment.

Here is a product with a Schraeder valve with a Viton seal . http://www.dieselorings.com/schrader-valve-fuel-injection-rated-1-8-mnpt.html

I did look on their website and it says their cores on available with several different rubber types, although it does say in another place, "compatible with all fluids."

( This subject attracted my attention because my Dad worked at Schraeder, and there were often valve cores laying around the house while he was working on projects. )

I'll look into this further, thanks for posting the information!

 

[Jance GTS]

I don't remember any rubber seal when I took mine off to remove the powder coat on my intake for paint. It just had some thread locker on it. Let us know what you find out, I'll replace mine with a new one as well.

 

[AZTVR]

I don't remember any rubber seal when I took mine off to remove the powder coat on my intake for paint. It just had some thread locker on it. Let us know what you find out, I'll replace mine with a new one as well.

The rubber seal that would be what was leaking for ViperTony is part of the replaceable valve core. They make those cores with several different choices of synthetic rubber. Viton, Neoprene, HNBR, FPM, EPDM . I assume that is to match sealing capability to the environment it is used in.

Who knows how ethanol and other modern additives might effect some of those materials as percentages in gasoline changes with new blends.

 

[hiss highness]

my guess would be the ethanol/methanol in either the fuel or additives

 

[ViperTony]

my guess would be the ethanol/methanol in either the fuel or additives

In CT, our gas has 10% Ethanol in it or at least that's what's posted at the pump. But I'm not the only Viper owner in CT and so far nobody else I know of has had my problem. I will definitely check the seal when it's apart.

I ordered a new valve from VPA but it will be at least a week before it ships so I won't have any photos for a while. I will post up the valve dissection as soon as the new valve arrives.

 

[EllowViper]

Scary stuff. My Dakota is parked right now due to a gas leak on the top of the tank where the fuel line comes off the pump and makes a 90 degree turn to the front. Looks like the same basic connection and fuel line set up that the Viper has. I blame it on the Ethanol blend that causes these hard lines to get brittle and break/leak. I was at Home Depot, smelt a lot of gas fumes, and noticed a pool under the truck. Gotta pull the bed to get at the top of the tank vs. dropping the tank. Easy fix if you can get at the quick connect on the fuel pump. Gas leaks not something to ignore.

 

[SEASNAKE]

I took the schrader valve out of mine when it started leaking and replaced it with a brass plug. No more leaks. Seriously, you only need the plug to check fuel pressure. You can always screw it back in if you need to do a pressure check.

 

[V10SpeedLuvr]

The powder-coater did not remove the valve. So *maybe* the powder-coating process/baking damaged the original valve causing it to leak.

Same thing happened to me. The powdercoater told me I'd prob have to replace the valve since he didn't remove it before baking. The cores have a very small fuel resistant o-ring around them for sealing. Once I installed the manifold, I started the car and sure enough, it was leaking due to the baking had cooked the o-ring. The valve core is no different from any other Dodge scrader valve. I mentioned to a Dodge mechanic friend I had to buy a new one. He told me they had a "parts car" out back at the dealership he worked at and he could give me the core out of it. I got that one from him, installed it on the Viper and no problems in 2 years.