Leaky Zenith carb.

[skeazle]

I got back from a nice easy ride in my 1930 Tudor sedan last week and the next day when I went out in the garage the smell of gas was over bearing. I looked underneath the car and there was a puddle of gas on the floor. Sure enough I noticed gas dripping from the carb. I tightened the bolt on the front by the bowl a little and I snugged up on both bolts on the bottom a little each. I thought that solved the problem but it still has a drip and I guess there is only one place left it can be at the big gasket that separates the two halves. Can I take the carb apart there just to put a new gasket on without disturbing anything else like jets and float etc.? It runs so good now and I would hate for it to get messed up by me tearing it apart. I just ordered a Zenith carb kit from Snyder's so I could get that big gasket. Yes I did shut the gas off when I parked it. Plus along with the gas leak there is an oil leak up front somewhere on the right side of the engine between the fan and the carb. I thought it might be that tube but the bolt wasn't loose on that. I checked the oil pan bolts and they were all snug. Any ideas? thanks, Jim

[oldforder]

If you are sure you shut the gas off when you parked it, then the shut off leaks. If it is shut off gas can't run out. Unless of course there is a hole in the bottom of the carb, and the gas from the carb bowl is all that ran out.

[ursus]

I have found a few carbs that had hairline cracks that extended out from the main jet plug. They are nearly invisible to the eye but enough to allow a steady drip until the bowl is empty. Previous owners had overtightened the plug, a drip started from the resulting crack, so the tightened them some more, and the crack enlarged some more, etc.

[skeazle]

I was out and started up the car and let it run for 10 minutes and no leaks. Then I decided to take the glass bowl off and drain that gas and when I put it back on and turned on the gas the bowl filled up like it should no leaks there but then I heard it running ou the bottom of the carb. I shut off the gas and held my mirror under the carb and sure enough the gas is leaking out of either the drain plug or the bolt next to it or both of them. I had just tightened the plug a little before I started it up. I'm thinking maybe the washer on the plugs are bad. That would be an easy fix. Can I get those at a parts place or hardware store? I hope it isn't a hairline crack. Jim

[Tom Endy]

More than likely the leak is coming from the float valve not holding. Possibly some crud has gotten into the valve, or the valve is just worn. This will allow the level of fuel in the reservoir to rise. At the same time the level of fuel inside the main and cap jets will rise until they overflow. The fuel will then run down into the intake throat and run out through the small drain hole in the base of the throat. From there it runs back to the hex bolt of the drain plug under the main jet and drips off onto the ground.

Quite often this leads people to think the drain plug is leaking and they end up over tightening it and stripping out the threads.

Slide your finger into the throat under the choke butterfly all the way to the jets and see if it is wet in there. If so, the float valve is not holding.

My method of resolving the issue of a float valve that will not hold is to install a float valve with a Viton tip. I put these in all the Zeniths I rebuild.

Tom Endy

[skeazle]

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Tom, I took out the short drain plug and the washer is fine. So I put it back in and turned on the gas and gas started dripping from around those two plugs. Where should I stick my fingers in do you mean where the air filter is? I never had one of these apart so I'm a little dumb at it. If the float is sticking is it a major job replacing the float valve? I was hoping I wouldn't have to take off the carb and operate, it might turn out worse than what is was. Thanks for all the help, I will go back out there and tinker some more. Jim

[larrys40]

I ditto what tom said. If you put a finger or two inside the carb throat and it is whet the cap and main jets are being topped and fuel is running out them into the throat. This is because the needle and seat is probably not holding ( shutting off the full fuel flow) when closed.

As he said a good viton tip is probably the best solution. I have had some that don't work though... so I test them with a vacuum pump to make sure they hold vacuum prior to install. If it doesn't hold vacuum it probably won't hold fuel.

Review what Tom said and I have noted above and you should be able to rectify the problem.
Larry Shepard

[skeazle]

Tom, I slid my finger in to the throat and there is some gas in there at least my finger tips came out with gas on them. What part # or description should I order and do I have to remove the carb( I would think I do) ? Is it a hard job? Jim

[Tom Endy]

Bratton's Antique Auto 800-255-1929. Modern float valve P/N 14310, $15.25

A few year ago I bought several that did not work at all. I took them apart and found them full of brass machine chips. It was easy enough to clean them out. I called Walt Bratton and advised him about it. He is at the mercy of his supplier, but he got on his case and the situation improved. However, I still take them apart when purchased and I still occasionally find machine debris.

There is a small plastic washer that holds the needle in place. Use a very small screwdriver and pry it out. Check with a magnifying glass and a strong light, then clean it out. Press the washer back in making sure it Is even and does not restrict the valve.

Replacing the valve in a Zenith is not difficult. Best to remove it from the car. You will probably need two fiber washers under the valve, Do not molest the float as a means to adjust float level.

Tom Endy

[Synchro909]

Guys, the OP also said he had turned off the fuel when the leak occurred. I agree it sounds like the float valve is faulty and replacement is the way to go. Clearly, the shut-off valve is also leaking. This is also an easy fix. I recommend: http://www.snydersantiqueauto.com/gas-valve-repair-kit
at $1.60, it is very cheap, easy to install and works well.
He also mentioned an oil leak and wondered about the return pipe leaking. I suggest taking the pipe off (2 small bolts) and inspecting the seals replace if necessary or use some permatex on both sides of them them before reinstalling.

[BILL WILLIAMSON]

The float chamber vent is hidden on the backside of the carb, just above where the carb halves separate. Very likely your shut off valve leaks through, when supposedly "OFF"---
Go to modelabasics.com for good info & pics & animations.
Bill W.

[skeazle]

Thanks everyone for the help! I ordered a new viton fuel valve and a gasket kit. I ran the car for 10 minutes and shut off the shut off valve and it ran for a minute then shut off. So that has to be working but the glass bowl at the firewall was still full of fuel. I'm so confused! If the gas was turned off so that the car starved for gas then why wasn't the glass bowl dry also? Jim

[Big hammer]

The glass sediment filter, fuel goes in at the top and fuel goes out at the top. Like a drinking glass if no water going in no water will go out, unless it's broken :-)

[Synchro909]

Originally Posted by skeazle

Thanks everyone for the help! I ordered a new viton fuel valve and a gasket kit. I ran the car for 10 minutes and shut off the shut off valve and it ran for a minute then shut off. So that has to be working but the glass bowl at the firewall was still full of fuel. I'm so confused! If the gas was turned off so that the car starved for gas then why wasn't the glass bowl dry also? Jim

The glass bowl stays full, even when you turn off the fuel and run the car till it stops. Your tank valve may be leaking enough to cause a pool on the floor but not enough to keep the motor running.

[mhsprecher]

I have experienced the Viton valves sticking on both of my Model As. I removed them and replaced them with the old style valves. Just sharing my experience.

[skeazle]

Tom, I sent you a PM.

[skeazle]

So I just took off my carb and the gas line is dripping gas in the pan about a drop every 3 seconds or so. I assume that means that is a bad shut off valve. Should I assume that that was my problem all along or should I still take the carb apart and replace the float valve? So far I haven't disturbed the carb in anyway yet. I hope I don't everything looks brand new. Is replacing the shut off valve a major job? Jim

[Farrell In Vancouver]

Like me you may fin both the shut off valve and the float needle by-passing. Start with the valve remove and replace or repair. then delve into the carb float needle.

[skeazle]

Thanks, Farrell I will do that. Jim

[Dick Steinkamp]

Jim,
If you have limited experience with Model As...or older cars in general, it is probably easier and less frustrating to replace both the carb and the shut off valve rather than taking the carb apart and rebuilding the shut off valve.

Separating the two halves of the carb can be frustrating and can result in a broken venturi or carb castings. While apart, you would normally completely disassemble it, soak it in carb cleaner, check the jets and passages for obstructions and damage, set the float height and reassemble it. This is not generally a job for a "rookie" although if you have some mechanical skills and an interest, learning can be a fun part of the hobby.

It would be easiest and more certain that you will have solved the carb leak problem if you buy a professionally rebuilt carb. I think they are about $200 from vendors like Bert's.

For the shut off valve, you will need to completely drain the tank. Then remove the valve, determine which one you have, and check to see if a rebuild kit is available for it. If it has been replaced by an aftermarket valve in the past, a kit is probably not available. Then you have to disassemble the valve, clean up the seating surfaces with fine grinding compound, repack it and reassemble it (and hope it still doesn't leak).

A new, reproduction of the original valve is $34 or so.

Before reinstalling the rebuilt old valve or a new one, I'd install the "pencil" micro filter on top of the valve to help insure "gunk" stays out of the carb.

[Synchro909]

To have a pool of fuel on the floor, obviously both valves are leaking.
To remove the valve under the tank, drain out the fuel first, undo the line to the firewall and then the valve. Have a rag handy to catch the few drops that will come out. I again suggest you use the repair kit I gave a link to earlier - they are great. While I was in there, I'd make sure the pencil filter is in place before reassembling. Fixing that valve might stop the carburetor leaking but only because no fuel will be getting to the float valve when the tank valve is turned off. Test the float valve by leaving the fuel turned on at the tank and look for a leak. I'd replace the float valve anyway while I am at it.

[wmws]

Correct me if I'm wrong but I don't see how that repair kit for the shut off valve will help with a leak through the gas line. That packing is to stop gas from leaking out around the handle on the valve. To repair the valve so it stops gas going through it you need to lap the valve cone usually done with very fine compound or tooth paste.

[wmws]

There must be a club near Hershey you could get some help from if you don't feel confident on taking the carb apart. I live about 1 1/2 hours from Hershey and would be glad to help if you brought it down.

[skeazle]

WMWS, I just ordered the repair kit for the shut off valve and now that I think of it maybe I should have just ordered a new valve. I do not want gas all over the floor of my car when I take off the valve. Is there any best way to drain the tank? I will probably change the valve plus replace the float valve in the carb. Wish me luck, I never did this before.This car looksi like new and I wasn't counting on all this at once. Jim

[Marshall V. Daut]

Jim -
If the on/off valve is shiny brass and leaks, it's probably one of the poor reproductions from a few years ago. They looked nice, but they would leak fairly soon. The bad news is that these valves cannot be repaired with the rebuild kits. They are "tossers". The new on/off valves in the past 10 years or so are much better and will not leak. If you have an original on/off valve, however, it would be worth your while to try and save it with the kit. If nothing else, you'll gain some valuable experience. Should the rebuild not work, THEN you could order a new valve. Of course, only put a minimum amount of gas in the tank to check for leakage over a couple days' time!
Marshall

[wmws]

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When I drain my tank I disconnect the line at the carb and loosen the other end at the firewall. Then rotate the line away from the carb. Get a hose of the correct size so it is a tight fit and slip it over the end of the gas line. Put the other end in a gas can and turn the gas valve on. Most of the gas will come out but not all so when you do unscrew the valve have a small container of some sort to catch the last bit. If you have floor mat rugs in your car you may want to take them out as if you do spill some gas on the rug you will be smelling it for a long time. I think new gas valves are about 35 dollars. Trying to repair one is a tedious process and not always successful.

[skeazle]

Marshall, My car was restored in 2009 and only has 3,000 mi. on since. So I don't know if the valve is a bad one or not but it must be for lasting only that long. I'm going to go broke ordering all these kits from Snyder's with the shipping costs twice or more than what the parts cost. Jim

[Fred K-OR]

You may be better off to just order a rebuilt carb from Bert's rather then try to repair the one you have. Then check out your shut off valve. I have a leaky valve on my huckster. So I purchased a line from the old valve to the firewall and in this line is a new valve. I think most of the vendors sell these items. This saves you having to drain your tank of gas.

Like mentioned, I have had hair line cracks in the body of the carb which caused a leaks. Also have had the threads stripped in the bottom carb part where the main jet screws into the bottom carb part. This causes gas to leak out into where the choke is and then drip off the bottom bolt. So like I mentioned above, you may be better off the buy a rebuilt carb from Bert's or one of the other vendors.

[Synchro909]

Originally Posted by wmws

Correct me if I'm wrong but I don't see how that repair kit for the shut off valve will help with a leak through the gas line. That packing is to stop gas from leaking out around the handle on the valve. To repair the valve so it stops gas going through it you need to lap the valve cone usually done with very fine compound or tooth paste.

The repair kit comes with new packing and a special fuel proof grease which is applied to the taper of the valve. It seals up the tiny scratches that allow the fuel to leak without lapping anything. Take my word for it, IT WORKS. The valve works smooth and easy afterwards with no leaks.
PS, the grease is in a small capsule that looks like one that might contain medication. DON"T swallow it if you ever want to leak again!!!

[skeazle]

Synchro 909, I hear ya! I do have the carb off now but I still have my gas line hooked up and it is dripping a drop of gas about every 3 or 4 seconds in to a pan. Won't the repacking kit only help for if the shut off valve inside the car is leaking? I took a video of the car and the leaking with my cell phone but I don't know how to post it on here. Jim

[Synchro909]

Originally Posted by skeazle

Synchro 909, I hear ya! I do have the carb off now but I still have my gas line hooked up and it is dripping a drop of gas about every 3 or 4 seconds in to a pan. Won't the repacking kit only help for if the shut off valve inside the car is leaking? I took a video of the car and the leaking with my cell phone but I don't know how to post it on here. Jim

Jim, For the carb to be leaking when the fuel is turned off, both the valve under the tank AND the float valve must be leaking. If you were to fix one properly and turn off the fuel EVERY time you leave the car, you will have no leaks but that is only a half arsed way to do it IMO. Neither should leak.

[BILL WILLIAMSON]

At a Hardware or Plumbing supply, you can get a NEEDLE type valve, that fits PERFECTLY in place of the ORIGINAL valve, for about $4.99. I've used them in BOTH my cars. DO use the "pencil" filter, in the TOP of it!!!
Bill Plumber

[wmws]

Synchro909. I will give the special fuel proof grease a try. I have an original valve that I would like to be able to use.

[skeazle]

I think I am going to put a viton float valve in the carb and replace the two paper gaskets and put it back on and open the valve up and see if it still leaks. If it does then I'll replace the shut off valve. Maybe I'll get lucky. Thanks everyone for all your help. Jim

[wmws]

I would not trust just the float valve to stop the gas. Henry put a shutoff valve on the car for a reason. If a tiny speck of dirt or rust gets in that float valve you will have a puddle of gas on your garage floor again.

[skeazle]

Hi Guys, Well I finally got to put the new float valve in my Zenith carb and replaced the big gasket but the smaller red washers I let go cause they looked good not mashed. Then I took out the shut off valve in the car and it was a piece of cake no leaks. I was expecting the worse but that is how I am working on 87 yr. old stuff. I opened up the shut off valve and presto the carb started leaking. So I took it off (2 min. job) now that I have it down pat. Well, I noticed that I should have replaced the red washers with new ones while I had the carb apart so I did that and it was good to go then. One thing I wasn't sure of when I took out the old float valve was that it had two red washers on the threads and I was not sure if it had to be that way. Maybe the extra washer acted like a shim. I put it back together with just one washer and put it back on the car and no leaks anywhere but it took a while till I finally got it started. Is that normal? Maybe it just took a little time for the gas to fill up the empty carb? I was about to give up and put a "For Sale" sign on it. I'll go out and try starting it in the morning to see if it starts better. I want to thank everyone who took the time to answer all my questions or give me their advice. The more I do with this car the more of an education I get. Jim

[Synchro909]

Putting a second washer under the valve is the standard way of adjusting the float level and is probably why it was there. Putting only one back might now mean your level is high. If the engine dies when you brake to a stop, that's where to look. Do a search here - there is plenty of info on setting the level and it is well described in Les Andrews' red book.

[johnbuckley]

here's my list (notice that a poor gasket between upper and lower bodies isn't on it as it doesn't cause carb leaking per se)
Zeniths: Causes of leaking
Problem: Remedy
1 Leaking/loose float valve gasket: Tighten/reseal/replace
2 Leaking float valve: (or crud stopping it sealing) Replace ( or clean up if possible )
3 Friction on float hinge: Loosen
4 Incorrectly set fuel level: Re-set
5 Hole in float: Repair or replace
6 Too many gaskest on main jet Check
7 Cap jet or main jet too short: Replace
8 Leaking/loose gasket at main jet: Tighten/reseal/ replace
9 Leaking /loose gasket at cap jet: Tighten/replace
10 Leaking or loose GAV housing threads: Tighten/ reseal/ replace
11 Leak at fuel inlet union: Tighten/reseal/replace
12 Loose/leaking gasket at strainer: Tighten/reseal/replace
13 Loose/leaking gasket at drain plug: Tighten/reseal/replace
14 Cracked housing/leaking passage plugs: Repair or replace

1-7 will generally manifest as poor running.
8-14 will generally not affect running unless there is excessive leaking.

[Fred K-OR]

Good list. I also found a striped thread on the cap jet or anyway it was the one that screws in from the bottom.t