Recurring fuel leak on the bottom of carburetor
 

I had a fuel leak on the bottom of the carburetor again. I replaced the gasket on the 1/2" bolt on the bottom of the carburetor, which stopped the leak. The gasket was inflexible. This is the third time I had to replace the gasket in 1.5 years of owning my Model A. I ONLY fuel up with ethanol free 87 or 89 octane. I bought 3 carburetor gasket kits from Mike's A-Ford-Able, and have used the gaskets from those kits. I don't use any fuel additives. When the fuel leaks, it stinks up my garage. The fumes get into my home A/C air handler, and my whole house smells like gas. The fumes nauseate my wife. I wish I had a detached garage, but I'm stuck with what I have. I really don't want my house to smell like fuel again.

Is there any way to prevent this red gasket from hardening?

Are there any tell tale signs that the gasket needs to be replaced?

Should I add gasket replacement to my preventative maintenance schedule and replace it every 4-5 months?

Thank y'all for any input.

Re: Recurring fuel leak on the bottom of carburetor
 

A couple more things. My car is not a trailer queen. I have driven her 1,900 miles in 18 months. I drive her often. The longest she sits without being driven is 2 weeks. I know that my problem/concern is not caused by old fuel.

Re: Recurring fuel leak on the bottom of carburetor
 

along with checking the float level, take carb apart and put gas in the float area and check to see if gas leaks near the bottom of the two jest. I have found loose jets and leaking, also found cracked threads on bottom of jet which allows it to leak.

Re: Recurring fuel leak on the bottom of carburetor
 

If it is truly the gasket and nothing else , brattons has an improved design replacing the red paper type gaskets that commonly fail over time. Read the description

https://www.brattons.com/28-31-zenit...asket-set.html

Re: Recurring fuel leak on the bottom of carburetor
 

Re: Recurring fuel leak on the bottom of carburetor
 

I have two gas shutoff valves. The first one is original. I leave I open all the time. The second one is a screw in type that was added by the previous owner. Every time I shut the car down, I close the second valve. It works well. Fuel was leaking even with the shutoff valve closed. I triple checked it this time. I typically check it twice to make sure it's completely closed. I think fuel leaked from the bowl.

Re: Recurring fuel leak on the bottom of carburetor
 

Thanks for the link, Mitch. My problem may very well be the red paper gasket itself. I will add 5 gasket kits from Bratton's to my next parts order.

Re: Recurring fuel leak on the bottom of carburetor
 

maybe the gasket, BUT the Main jet needs to have an indented (dished out) tip,to prevent capillary action leaks when engine is off. Also a Good gas valve.Make sure all old gaskets are removed and use the new blue ones.Proper float set.

Re: Recurring fuel leak on the bottom of carburetor
 

Now that's being prepared,,, I like that

Re: Recurring fuel leak on the bottom of carburetor
 

I only have old stock fiber gaskets, no problems with leaks, the ones on the car now are 30 years old and don't leak, recently I had to rebuild a BMW isetta carb and had problems with the red gaskets leaking, looking close at them the surface was not flat and smooth like the old stock ones, I had to sand them on fine paper, then they worked

Look at the surface of the new gaskets to see if it is bumpy

Perhaps I don't have problems because I do use ethonal gas only

Re: Recurring fuel leak on the bottom of carburetor
 

Had a similar problem - in my case the shut-off valve was hard to open and close - and still is. But what seems to have ended the leak problem - at least for now - was to take off the glass sediment bowl, open the valve, and rock the car back and forth to flush out a lot of powdery rust that was apparently keeping the valve open just enough to allow a very slow leak of fuel. May eventually need a new valve and a real flush out of the tank but, for now, she isn't leaking in the garage.

Re: Recurring fuel leak on the bottom of carburetor
 

I found that on my carb I had screwed the GAV fitting (the thing that the GAV valve screws into) in to far. It cracked the iron casting where the fitting screws into and thus the gas leaked out there. Don't know if this is a possibility or not in your case. Or do you have a crack somewhere else in the iron casting????

Re: Recurring fuel leak on the bottom of carburetor
 

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Re: Recurring fuel leak on the bottom of carburetor
 

Take a plumbers wire brush to clean out the threads for the plug. Might be part of your problem along with the gasket.

Re: Recurring fuel leak on the bottom of carburetor
 

All above very wonderful suggestions have great merit.

Then, sometimes, after trying everything, it may make sense to look at it another way.

For example, just suppose:

1. The part of the bolt head that contacts the gasket has a burr on it, maybe caused by some former owner's loose fitting wrench, or is askew, and does not tighten the gasket all around the 360 degrees; and/or,

2. The part of the carburetor that receives the gasket is maybe too small for the gasket, or the gasket is too large to allow it to seat on the carburetor surface, or this metal seat is askew; and/or,

3. The part of the carburetor that receives the gasket has a raised lip or burr on it ........... on one area where the gasket is not allowed to seat and become "totally" compressed 360 degrees.

Re: Recurring fuel leak on the bottom of carburetor
 

As said before, the carb gaskets are very hard !

For years I have used Napa Aviation Form-A-Gasket Sealant Liquid, it is gas resistant; I use a tooth pick and put a small amount on the gaskets for the main and cap jets, the float valve, the bolt below the main jet, and on the front screen; I also use it on the threads when I install the GAV housing; a number of these locations are below gas level in the bowl.

This has worked well for me.

Ron