carb leaks

[Tarheel Tom]

Before I order a new carb....are there any conventional wisdom I am missing....

I have cleaned the whole body (zenith), new jet seats and gaskets...disassembled and reassembled.....tested the float.....cleaned channels..... tested the base with gas in it....even teflonned some of the connections.... no matter, everytime I hook it up and turn on the gas.....it drips out the back and wets the gasket ....every second...drip drip drip...
clearly the float is not stopping the flow.....I replaced the float valve and polished every surface so it could float shut...IE trying to stop any sticking......still drip drip drip.

[tbirdtbird]

have you rebuilt other carbs in the past?

[Tarheel Tom]

no...where could I go wrong (probably a long list)

[ModelAMike1930]

Did you try carb cleaner on the float passages ? The alcohol in the gas gums things up. Happened to me also and the carb cleaner did the trick.

[Tarheel Tom]

I cleaned the body with a good solution and checked passages. all looked good. also did a lower body check....filled bowl with gas....until it came out jets...let it sit ...no leaks


It only leaks when I bolt it on. The gas connection does not leak at first....only when it starts to drip does a little gas appear around the line connection.....I figured it was because it was overflowing. ????

[Fred K-OR]

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Originally Posted by Tarheel Tom

I cleaned the body with a good solution and checked passages. all looked good. also did a lower body check....filled bowl with gas....until it came out jets...let it sit ...no leaks


It only leaks when I bolt it on. The gas connection does not leak at first....only when it starts to drip does a little gas appear around the line connection.....I figured it was because it was overflowing. ????

So it leaks around the line connection at the carb? If so, put some Teflon tape like Tom Endy mentioned around the little "bulb" on the end of the gas line. Make sure it does not plug line.

[hale1776]

Float level when correct is just a tiny bit lower than the top of the jet. Lower float level see if that helps.

[Mitch//pa]

your first post was a little miselading,
if a carb floods from the float valve not sealing it will be running out the choke plate area.. (air horn) where an air filter would go if being used... your leak at the fuel line ferrule is a sealing issue of the gas line to carb body... there are many things to check.. whats the condition of your fuel line ferrule and the seat that it mates against in the carb.. sometimes the line has to be snugged very tight to seal..i always use a line wrench

[BILL WILLIAMSON]

Tom,
LISTEN to Mitch, he knows his STUFF! My "guess" is that it's the line fitting & it "tracks" around & it's hard to tell where it's coming from. The corner of a blue paper towel helps locate the leak. Try rubbing Vaseline on the ferrule & fitting, snug it down & with a good tubing wrench, pointing straight forward, push down on it with a straight arm & see if you can feel it "give" some more, thus "squeezing" the ferrule tighter on the line. The ferrule HAS to be squeezed TIGHT on the tube, LIKE A WEDDING RING ON A FAT MANS'FINGER! or it'll LEAK. DON'T use Teflon Tape or GOOP!
Bill W.

[KGBnut]

There really isn't much to go wrong with these carbs. Short of being cracked, they are rarely a total loss. I wouldn't spend money on a new one.

There are only a few things that will cause that drip...drip...drip. The fuel is supposed to come into the float bowl, fill it up to a certain level, and then stop. If a drip is your only problem you don't need to worry about anything after that point. The things that could be at fault:

Fuel line fitting
Carb Filter/Seal
Float Valve/Seal
Float
Drain Plug/Seal


The Fuel line fitting, the filter, and the Drain Plug are easy to check and rarely the problem. In my experience, the drip is almost always a problem with the float, or the float valve.

The float valve admittedly can be a pain. When in doubt, replace the valve. You will get a lot of opinions about which valve is best. Personally, I like the original style (about $7.00). Then make sure the float is adjusted correctly.

Lastly, and this is the thing that most people miss, check the Seal(s) under the valve. If you don't have a good seal here, fuel will seep around the valve and cause your drip. It can be tricky because you often have multiple layers of Seal (for adjustment) and the surface of the carb here is often irregular. Make sure the valve is good and snug to compress the Seal. In some cases you may need to use the thinest layer of Permatex between the carb body and the last Seal.

Good luck.

[Tarheel Tom]

if the ferrel leaks....does it come out the air intake. I thought the leak came from inside the carb. it did not seem to leak around the ferrel.....i will check and retighten....check with a blue paper.....if not leak at the ferrel...then I am back to a float problem?

[Tarheel Tom]

Thanks for the pointers......will check each one again...til I get no leaks.

I did re order the float valve....and got original style....was thinking of getting the one with the special tip.

[Brentwood Bob]

As #13 says, check the valve by blowing into the gas inlet. It can be done with the top only. There should be no leaking down indicating a good fit of the seat.

[Ron in Quincy]

If the carb is leaking from the gas line connection, the gasket between the housings will get wet from the gas; do to the angle of the carb, the gas will run around to the back side of the carb, down the carb and drip from the mounting bolt.

Suggest you check the gas line for a tight connection and also a good seat in the carb connection.

Ron

[Gary WA]

Cracked ferrel brass hard to see

[1931 flamingo]

Put a new ferrulle on.
Paul in CT

[kenparker]

As mentioned above, the area where the ferrel seats is pitted or even rough looking it needs to be polished. Either with a polishing stone on the end of a Dremel or a countersink drill bit. Either way be VERY careful and keep tool square and centered. Also if the ferrel has ben used and/or tightened several times they can become cracked, which is hard to see, or scored/scratched, which although may look ok, it will not seat completely.

My option would be to cut the Ferrell off and install a new one. They can be obtained at your auto parts store of a hardware store.

If the ferrel is leaking it will run down the threads or come out the line - in the center of the "nut' - then run under and then run down the gasket, giving the impression of the gasket leaking. When she is sitting still, as in not running, and the float is working correctly, the gas should be 5/8" below the gasket.

Other area to check. Is your Float Valve the one that comes with the kit or is it one of the neoprene tip Float Valves or a "Grose Jet" which is a double steel ball type of valve. Both the Neoprene tip and Grose Jet are better options.

keep us posted. ken

[jhowes]

I have heard contradicting opinions on the neoprene and double ball type valves. Does anyone have a semi scientific comparison of the three types of valves? I have used them all and still don't know which is the best solution.

[Ron in Quincy]

jhowes,

I personally like the original type float valve, have had no problems with them and have rebuilt many Zenith and Holley carbs. I get my float valves from A&L Parts.

Eon

[KGBnut]

I was motivated to take a look at an old Zenith of mine that I knew had a leak. As a result, I have to amend my notes from earlier.

There are a few other places that could be responsible for a leak, even with a perfectly good float valve. The good news is they are really easy to check. Both the main jet, and the cap jet are essentially siphons that are connected to the float bowl. If the seal at the bottom of either of these jets fails, it will empty the bowl through the air intake. Similarly, if the GAV needle housing is not sealed tightly around its threads, it will leak down the side of the carb, and again empty the float bowl.

These areas are very easy to test. Remove your carb and take out the one bolt to separate the top and the bottom. No further disassembly is needed. Thoroughly dry the carburetor so you can easily spot new leaks. Fill the carb bowl about half way...high enough that it is above the opening for the GAV needle housing in the carb body, but not so high that it is above the tops of the main and cap jets. Look carefully for leaks around the around the threads on the needle housing and at the bases of the two jets. If you have a slow leak, you may have to leave it sitting for quite a while before you spot the leaks.

On mine, it was the threads on the GAV needle housing that were the problem. Mine are the inconvenient 13/32 size, so it is trick to get that good and snug. I have to get a 13/32 wrench.