Gas is still leaking

[bogiediver]

Searched and didn't find specific answers...

I took my gas shut off out and per the procedure several Barners helped me with, I lapped the innards, put in new packing. The initial test indicated it worked. After re-installing (with the finger filter installed), before hooking the gas line to the firewall - in the off position - nothing, as hoped... turn to on, gas flowed... back to off, a drip or two and then nothing - yeah!

Also worked with my Tilly carb to flatten the mating surfaces by filing and sanding. Also seated the needle valve. Both per the Tilly 'Yellow Book' instructions. Since the car ran well otherwise, I did not completely rebuild the carb.

Connected the interior gas line to the firewall connection for the glass sediment bowl. Connected the fuel line to the engine compartment side of the bowl. With the fuel valve off - nothing into the bowl... good.

Open the value - bowl filled up and into the line toward the carb. Closed the valve - stopped flowing - good.

Attached gas line to the carb.

Opened the valve, car started. Let it run awhile, turned off the valve - car ran for a bit and died. Turned off valve.

All was good for the next week as the car sat in the garage.

Turned the valve on again, started the car several times while adjusting the generator and then installed a EVR-style cutout and testing the cutout - no problems with the car starting/running.

At the end of the day - closed the valve, let the car run out of fuel 'til it stopped.

Next day and every day since - fairly strong gas smell in the garage. Aired out garage, 8 hours later - smell is back.

This implies to me that both devices must still be leaking somewhere. If either (the shut off valve or the needle valve) was turning off the fuel as they should - there would be no gas smell.

Now the Tilly was pretty badly warped, but I filed and sanded until there were no high spots. Another thread suggested using two gaskets - that is counter-intuitive to my past learning of gasketing... So I'm probably going to exchange my Tilly for a correctly and fully rebuilt one.

For the gas shut of valve - does anyone rebuild these that has more experience at it and has a track record of getting them right? Really don't want to go to a cheap repro or using a ball valve.

Sorry for the dissertation - hoping it will preempt some questions on my process.

[Kevin in NJ]

How did you test your shut off valve?

[700rpm]

It sounds like you did the valve right. You might check the packing nut and make sure it's still snug. Don't over tighten. I think you're going to find the trouble in the carb, though gas shouldn't be getting there if the valve is working properly. Can you lay some paper towels or something on the floor to determine more closely where the gas is leaking?

[Louis]

Why don't you order a new shut off valve from Snyder's for $36.95, made in the USA and guaranteed not to leak, I put one on last year, And not a drop, Got tired of rebuilding it only to have it leak agin, Good luck .

[bogiediver]

Kevin-

The initial test is what I described in the original post - "After re-installing (with the finger filter installed), before hooking the gas line to the firewall - in the off position - nothing, as hoped... turn to on, gas flowed... back to off, a drip or two and then nothing - yeah!"

The test was to have only one short section of gas line connected so that as I added gas to the tank, I was testing two areas:
- the threads of the valve into the tank
- the actual operation of the valve to shut off the gas flow

As I poured gas into the tank, there was no leak from the threads where the valve screws into the tank & there was no gas flow out the open end of the gas line that was only connected on one end to the valve.

Then I opened the valve and gas flowed freely from the open end of the gas line (into a bucket...). Closed the valve and it stopped.

That was the initial test and it worked as expected.

Then connected the next section, then the next, then the carb and all worked as expected; until I had open and closed the value & started and stopped the car several times - then the leak reappeared.
.
.

700rpm-

The packing nut is snug - the value handle is a bit hard to turn, but not overly...

Quoting you - "gas shouldn't be getting [to the carb] if the valve is working properly" - kinda my point...

I have cardboard under the car - it's leaking from the carb - no doubt about it. It appears to be from the air intake primarily... but, gas migrates along the entire surface of the carb, so it's hard to tell. I've wiped off the surface of the carb and then used the air gun to blow it dry - but it's still hard to pinpoint where it's originating from.
.
.

Is my logic flawed that both the shut off and needle valve are leaking? That if either of them worked as they should, there would be no leak?

Still hoping for a recommendation for someone who re-works shut off valves with a successful track record...

[bogiediver]

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Louis-

Perhaps that is the right answer - get the new shut off valve and a properly rebuilt carb and be done with it...

[Fred K-OR]

Bogie, I had the same problem with an after market new valve. I gave up and put another shutoff in line with the one that is in there. Some of the vendors sell this type of kit. Mine was a driver and I did not care. If yours is not, then you may need to just get another valve like mentioned above.

[Louis]

Bogie,
Like I said, The valve from snyders is a well built shut off valve made in the USA plus "guaranteed" not to leak.
I have got into a habit if Im going to shut the eng. off for more then 30 min's, I let it run for about 15-20 sec's with the shut off valve closed to burn some of the gas in the carb, then turn the key off, plus, I do it every time I put the car in the garage at the end of the day, Not a drop.
Even if your carb. has a small leak, this will stop it, And after a few times of forgetting to turn your gas valve back on,
You'll be a happy driver . Good luck.

[H. L. Chauvin]

Approximately 10 years ago, tried to order an A9193 fuel shut off valve repair kit from a very well experienced Model A Parts Supplier & Master Model A Mechanic from the State of Illinois. Ron told me about his experimenting with the re-lapping of about 50 or so used Model A fuel shut off valves, & trying to install new A9193 shut-off valve packing repair kits.

After re-lapping, installing new kits, & testing same under water with air pressure, out of the 50 or so used fuel shut off valves, only two (2) or three (3) stopped leaking.

Took his advice, bought a new fuel shut off valve, & never since had a probelm.

[1931 flamingo]

Do yourself a favor and get the electric fuel shut-off solenoid, and then fix your carb problem:float, needle/seat, etc. JMO
Paul in CT

[columbiA]

I too would buy a US made shut-off valve-the off-shore ones are junk.Also check to make sure it,s not leaking at the column bracket on tank.sometimes the leak is so small,it,s not enough to drip on the floor,but will evaporate & make a big stink. I,ve fixed leaks with Seal All & it worked very well.On the carb,try lowering the float level a bit & see if the dripping stops.

[Peter J]

I'm down to 1/4 tank. Tomorrow I'm going to drain it and install a ball valve. Tried to unsuccessfully rebuild two valves with no luck. Don't trust an electric shutoff If it goes bad, it shuts off in the closed position.

[V4F]

i took my shut off out of the system completely . did not like the smell in the cab at all . absolutely no troubles ! the electric shut off is a great piece . mine worked for yrs with no problems . the reason i have no shut off is because i have a weber & they dont leak . good luck as the gas smell suxxxx ............... steve

[BILL WILLIAMSON]

Fussed with my shutoff valve, no luck, took it to the hardware store and bought a needle type valve for $4.79, fits perfectly in place of yhe original, all standard threads. Don't forget to put your standpipe filter in the new one! Bill W.

[Tim B.]

I think that 700 RPM has got it right. Even if the shutoff valve is leaking by, the float & needle should stop the flow at the carb. I suspect the float is too low, the needle valve is sticking or there is a dimple in the float where it meets the needle so the needle won't seat fully even if the float is working. Put an extra gasket under the needle valve and see if the leak stops if it does the problem is with the needle or float. I had the same problem and it was the new needle valve not seating because float was not high enough. The extra gasket solved the problem. A lot cheaper than a new carb. Tim

[jerry tocci]

If the fuel line from valve to sediment bowl was off, could you tighten (spin) the shutoff valve??? If it dose, take the valve out, remove lead packing, and sweat solder on the threads, far away from the tank. This will help the valve seal to the tank, better than any tape or goop.

[Kevin in NJ]

I was interested in how you tested because just a little gas in the tank is not a good test.

You need to have some pressure on the valve by using air pressure. Chuck up the valve to your air compressor and put it in water.

I was going through my valves and found one untouched original valve that has a slight leak. A small stream of bubbles. I tightened the packing and the bubbles cut back to a very small bubble once in a while. Then I tightened the packing a bit more and no more air coming out.

On my next order I will get some kits and rebuild a few to have on hand. I will report my findings. I did notice that some valves, just looking down the holes, had some obvious scratches on the surface. I am curious how a scratched one would work. The one I tested the rotating surface was shiny and smooth when I looked down the hole.

[bogiediver]

@ Kevin in NJ -

I agree - a small amount isn't necessarily a complete test - but if it's already leaking with a small amount, the only thing filling the tank would do is give me more gas to drain back out...

@ Jeff/Illinois -

I talked to Snyder's... they guarantee the valve will not leak for 3 years (indicated they have not had a return when the valve is used with the in-tank finger filter; which I plan to do). For $30 or so, seems like what I should have done in the first place... (is it 'still learning' or 'still stubborn'?)

@ jerry tocci -

The valve is OK in the tank - no leak from those threads... when I put it back in the first time - the valve didn't tighten up with the correct orientation to the gas line... So I used an ethanol-proof thread sealer which lubed the thread enough to allow me to tighten the additional 1/2 turn needed to line it up correctly with the gas line. It's supposed to be a thread sealer that allows for future removal if needed - guess I get to find out if that is true...

@ Tim B -

I agree - it probably would be less $$$ to try what you suggested, but I'm just not comfortable doing all the fine work on the carb with bead blasting & solvent soaking (don't have the tools); the various 'welch' and lead plugs to take out and replace; the fine wire to clean passages, etc, etc - and, most of all, don't have the patience... got'sta know your limitations...

And my wife said this isn't the first time there's been an issue with this Tilly. Back in the early 90's on a long trip, the heat must've gotten to it, because her Dad 'band-aided' it to finish the trip, but then Dad got sick and wasn't able to do anything further before he died. And she thinks it was not touched since...

I was referred to a local source for rebuilt Zenith carbs, at a reasonable price, that comes recommended - so I've decided to get the rebuilt. Hopefully the cast iron won't warp as the pot metal did...

I'd like to thank everyone for their insight and assistance. I hope to have both the valve and the carb before the end of the week so I can get them put in over the weekend... I'll try to remember to report back...

[Tom Wesenberg]

If the taper on the valve has scratches and you want to save an original valve, I would think you could fill the scratches with solder, then polish on the lathe.

When I first bought my 29 Tudor I lost a full tank over winter, so I took the valve apart and polished it on my lathe, then worked it and the carb valve with toothpaste. It hasn't leaked since and that's over 10 years ago. Be sure to use the stand up screen in the tank.