MTFCA Forum

I have a leaky petcock at the sediment bowl. It is acting the same way as the petcock at the radiator. I replaced the radiator petcock and the leak stopped. I am going to order a new petcock from Lang's. Is there anything different I should know about replacing the gas petcock as opposed to the radiator? Thanks in advance for any help.

David they are the same.

If you want you can rework your leaking ones by disassembling and use fine valve lapping compound to reseat them. Afterwards I use an ultra fine polishing compound or toothpaste. Install a good spring, washer, and cotter pin. Should last another 50 years or so.

All the Best,

Hank

Ordinary soap (the sludge from the bottom of the soap dish) works well for sealing in gasoline service. And the price is right!!
Take the valve apart and smear the plug with the soap. It’s always worked for me and it is “era correct “ as it is recommended in old repair books!!

Thanks f'or your help guys. I think I will go ahead and order a new reproduction petcock from Langs and be done with it. Thanks again,

After you remove it to replace it...don't pitch it. Give it to someone who will fix it.

As someone who grew up with NOS parts overflowing flea market tables in the '70's, you'd be surprised at the items that we never thought would become scarce, and now are...

Amen ! Scott, My sentiments exactly

Be careful with the new petcock because it is easy to score it and end up with something that leaks.
I don't know about soap but it might be good to put a bit of lubrication on the sealing surface before using it.

After you do some lapping as suggested above you need some of this. I did get it from one of the T vendors but not sure which one.

EZ Turn is a specialty lubricant/sealant used for fuel and oil line valves & is resistant to high temps. Especially effective where high octane fuels and aromatics are present. EZ Turn is also extremely efficient as a gasket paste & anti-seize agent. EZ Turn will not gum, crack or dry out. Each shipment is independently tested. Excellent for tapered plug valves, aircraft engine manufacturing, and marine applications. EZ Turn is the functional equivalent of fuel lube.

Use E-Z Turn sparingly on petcocks or small orfices as it's tenacity can partially block or block off small passages.

Here is where I got my EZ Turn

https://www.google.com/url?sa=t&rct=j&q ... Ov3XytxK9Z

Seems the sediment bulb can often be "weepy" without leaking enough to drip. From the fitting soldered and riveted to the tank, to the sediment bulb threads, the shut-off valve and finally the drain petcock, all in turn need to be fitted to avoid leakage. I may be wrong, but I believe modern gasoline is a bit harder to contain than what we were using 40-50 years ago. It's not uncommon to find that even a brand-new petcock may "weep", and can be improved by lapping. E-Z Turn is great stuff that keeps valves in the fuel line . . . well, easy to turn !

I will try EZ Turn. I just ordered a tube from Langs.

Actually, all gas/gasoline/oil valves of the cone or wedge design are absolutely ancient. I've seen pictures of identical valves made of bronze, used on Roman galleons for controlling water.

Any propane or natural gas supplier carries a compound used to coat the two surfaces to insure a gas tight, yet easy turning valve. Keep that in mind for future reference as they'll be happy to give you a small amount for free.

Plumber that does gas lines should have it too

I replaced the sediment bowl petcock today using Easy Turn. So far so good. No leaks. Thanks Chris for the Easy Turn suggestion and thanks to all you other guys for the suggestions and comments.

Oops. Should have said EZ Turn.