Replacing Schrader Valve Help

[ViperTony]

On my GenII, this would be the third time I'm replacing the Schrader on top of the intake manifold. It's leaking fuel, again. It's not leaking at the intake manifold, threads where it screws in but rather through the top. With cap removed, fuel system pressurized, gas drips out. Even tightening the cap as tight as I can it leaks. I'd rather not have the engine catch on fire so I have to solve this. This is the same issue, 3 times, in as many years. So I'm bit stumped why this keeps happening to me.

I may also need to re-tap the threads for the valve. When my powder coater worked on the intake, he screwed in the valve and essentially screwed up the threads. It's a bitch getting the valve in/out and I'm certain when I remove it this time I'll have to address the threads.

Question: I'm thinking using a thread chaser first to see if it corrects the thread problem. I don't want to drill/tap or use a helicoil (not sure that's a good idea on a fuel connection). What size thread is the schrader valve?

This is the littler bugger causing me trouble:

Schrader-Valve.jpg

[jdeft1]

*******

[jdeft1]

If the valve body doesn't leak at the manifold... don't pull the fitting out again. Just remove the valve core and replace. Need the thread slope of the valve core? (the seating surface that screws out of the fitting?)

Do you have a Schrader valve tool?


I see your pic and would be happy to fix it in my machine shop for nothing but some company. It's an easy job to get it fixed. Tony.

Cheers!

[plumcrazy]

I read the title and said WTF, this isnt the first time....lol

[ViperTony]

If the valve body doesn't leak at the manifold... don't pull the fitting out again. Just remove the valve core and replace. Need the thread slope of the valve core? (the seating surface that screws out of the fitting?)

Do you have a Schrader valve tool?

I see your pic and would be happy to fix it in my machine shop for nothing but some company. It's an easy job to get it fixed. Tony.

Cheers!

Where are you located? PM the details if you want. But I ended up replacing the valve entirely. I pulled it out into my driveway and let it idle when I smelled gas. Sure enough the valley atop of the engine block began filling up with gas. This is with Schrader valve cap screwed on tight. New valve does not leak. So for now, it's fixed. If it leaks again I'm just going to cap off the connection. This is the third valve replacement in as many years. The only commonality they share is that I purchased all three of them from the same vendor. I'm wondering if it's a bad batch. I do have the old valve. If you want to look at it and diagnose it I'll send it you.

Thanks,
Tony

[jdeft1]

^ I haven't seen the previous forum references .. (apparently this is an on-going problem). It seems simple from your initial post. There is a cool little tool that can screw the valve seat tighter (any parts shop has one). The internal components of the valve body just screw out/in... The tighter you screw it the better it seals, to a point. Sorry if I'm being obtuse here but it's simple Schrader valve. What's the problem?

What's your fuel pressure at idle?

It's a different problem if it's leaking between the valve body and the intake ... (The valve cap is just to keep crap out it it.... not to seal)



I'm in Northern VA/DC area. I do small work for local hotrod guys or restorers as a hobby.... stuff like antenna nuts or special fasteners, custom do-dads etc... I love that $hit. There's lots of cool cars out there that need something special.....


Cheers

[ViperTony]

^ I haven't seen the previous forum references .. (apparently this is an on-going problem). It seems simple from your initial post. There is a cool little tool that can screw the valve seat tighter (any parts shop has one). The internal components of the valve body just screw out/in... The tighter you screw it the better it seals, to a point. Sorry if I'm being obtuse here but it's simple Schrader valve. What's the problem?

What's your fuel pressure at idle?

It's a different problem if it's leaking between the valve body and the intake ... (The valve cap is just to keep crap out it it.... not to seal)

I'm in Northern VA/DC area. I do small work for local hotrod guys or restorers as a hobby.... stuff like antenna nuts or special fasteners, custom do-dads etc... I love that $hit. There's lots of cool cars out there that need something special.....

Cheers

I will check out the tool. Not sure what my fuel pressure is these days as I haven't checked in a couple of years. I'll find out when I get to the dyno soon.

[tagoo]

Are the replacement schrader valves you are using compatible with gas? IIRC, the core of the schrader valve has some plastic or rubber rings on it. I would believe that those are to help seal. If those rings are not made of a suitable material, it may be that the gas is destroying the seal. Just a thought.........

[ViperTony]

Are the replacement schrader valves you are using compatible with gas? IIRC, the core of the schrader valve has some plastic or rubber rings on it. I would believe that those are to help seal. If those rings are not made of a suitable material, it may be that the gas is destroying the seal. Just a thought.........

Good question. I'm using Mopar Part # 05245193.

[jdeft1]

Fixed?