Leak on top of carb...

[TomInCologne]

Hi guys,
this is puzzling... at least to me...


I came to the car yesterday and found a puddle of fuel under it, about 1,5l. My carb has always been leaking but it was only dripping, not a lot. Now this is new, 1,5l is definitely too much...


Looking at the carb, the fuel seems to come out the top through the accelerator axis or thereabouts. Does that make sense? I thought that if the valve in the float chamber is leaking, it would like out somewhere on the bottom of the carb...


see photo...


Thanks in advance,
Tom

[Y-Blockhead]

How much play is in your throttle shaft?

[TomInCologne]

Originally Posted by Y-Blockhead

How much play is in your throttle shaft?

quite likely too much... but should fuel flow out of there?

[Will N]

It doesn't make any sense for gasoline to be leaking from the throttle shaft. It would have leaked out of the mouth of the carb past the choke well before the level got high enough to come out of the throttle shaft. Are you sure it is gasoline that has puddled under your car? You might have a coolant leak in your head gasket or a crack in your head or block that is running past an intake valve, into the intake port and down through the carburetor, pooling on the closed throttle butterfly and leaking past the throttle shaft.

[TomInCologne]

Originally Posted by Will N

It doesn't make any sense for gasoline to be leaking from the throttle shaft. It would have leaked out of the mouth of the carb past the choke well before the level got high enough to come out of the throttle shaft. Are you sure it is gasoline that has puddled under your car? You might have a coolant leak in your head gasket or a crack in your head or block that is running past an intake valve, into the intake port and down through the carburetor, pooling on the closed throttle butterfly and leaking past the throttle shaft.

well, it doesn't leak when i close the fuel shut-off...

[Steve Schmauch]

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From your picture it looks like your leak is actually coming from where the gas line enters the top of the carb. I would look at the surface inside the inlet to make sure it is smooth. Next, I would change the compression ferrule on your gas line. Make sure it is located properly on the gas line! This should cure your gas leak.

[TomInCologne]

Originally Posted by Steve Schmauch

From your picture it looks like your leak is actually coming from where the gas line enters the top of the carb. I would look at the surface inside the inlet to make sure it is smooth. Next, I would change the compression ferrule on your gas line. Make sure it is located properly on the gas line! This should cure your gas leak.

don‘t think that is leaking. see, there is some liquid under the throttle axle…

[Banditorama]

I see where it looks like its coming from the throttle shaft. It looks like its wet up above the throttle shaft, or is that just a shadow?

The only thing I could think would be fuel flowing out of the idle jet port above the throttle plate. But, if that was the case it should be pouring out of the main jet which sits lower than that port.

I'd Pull the carb off and see if you have gas pooling up in the manifold. Also, see if there's gas pooling up in the bottom of the carb

[Gary WA]

Originally Posted by TomInCologne

Hi guys,
this is puzzling... at least to me...


I came to the car yesterday and found a puddle of fuel under it, about 1,5l. My carb has always been leaking but it was only dripping, not a lot. Now this is new, 1,5l is definitely too much...


Looking at the carb, the fuel seems to come out the top through the accelerator axis or thereabouts. Does that make sense? I thought that if the valve in the float chamber is leaking, it would like out somewhere on the bottom of the carb...


see photo...


Thanks in advance,
Tom

Make sure all the jets are tight with one gasket, no gasket on idle jet.

[Gary WA]

Originally Posted by TomInCologne

Hi guys,
this is puzzling... at least to me...


I came to the car yesterday and found a puddle of fuel under it, about 1,5l. My carb has always been leaking but it was only dripping, not a lot. Now this is new, 1,5l is definitely too much...


Looking at the carb, the fuel seems to come out the top through the accelerator axis or thereabouts. Does that make sense? I thought that if the valve in the float chamber is leaking, it would like out somewhere on the bottom of the carb...


see photo...


Thanks in advance,
Tom

also that gasket looks like the water outlet gasket not carb gasket

[Wick]

Looks like a side bowl carburetor to me. At some point someone has put a bolt in the flange that was too long and cracked the carburetor Right above the adjustment screw.
I have also seen the bowl with a Crack. All it takes is someone to drop the carburetor on the floor to Crack it.

[nkaminar]

Banditorama may be correct that the fuel is coming out the idle jet (Post #8). But it is also probably coming from other places too. 1.5 liters is a lot to have come out the throttle shaft. It looks like it coming out at other places too. It may be that the float valve is not closing. You are going to have to take the carburetor apart and do an inspection. Test the float valve by blowing into it when it is closed. Just a little spec of dirt can keep it from closing completely. Best practice is to shut the fuel off when parked.

[47topless]

Is the fuel in the inline gas filter clean?
Before going to the work of removing the carb, I would disconnect the fuel line, remove the fuel/air mixture screw, open the lower drain and blow some air in the holes. That may loosen some debris and should free up a stuck float. Put it back together and see if that helped the leak. Worth a try with little effort.
Good Luck

[lrf]

I got to agree with Gary WA. That gasket is incorrect, it shouldn't stick-out beyond the manifold and carb connection. LRF

[TomInCologne]

guys,


thank you all, i will go through and check everything. I have been out over the weekend doing about 150 miles without any problems except i have to remember to shut the fuel off when parked.



I will check things over the following days and will post any findings, positive or negative in this thread.



Re the gasket: I assume that i got it from one of the suppliers as a carb gasket, but it may be that i mistook another gasket for the carb gasket. Does any other gasket fit? water outlet, i think, is not the right size?

[johnbuckley]

Very puzzling ...long shots here!... is there some particularly nasty gasket gunge on the carb/manifold gasket ?..Is it really fuel there at the throttle shaft ? ... for 1.5 litres to leak this cannot be just fuel condensing within manifold ....surely the fault must lie with the float valve not closing/incorrect fuel level for some reason with fuel capillarying up via soaked gasket [ all assuming the fuel leak evidence ( paint dissolved) near inlet is irrelevant !]

[jimvette59]

How does the engine idle? It looks like the air fuel adjuster is all the way in. That top has been cracked and repaired. I would get another top and see if that helps. JMO

[TomInCologne]

i have not had time yet to check the carb, but a thought crossed my mind...


My mixture screw is more or less closed, maybe the vacuum pulls in the fuel into the top of the carb and after the shut-down of the engine, the fuel will keep on flowing as the fuel level in the tank is higher? (suction lifter?)



Before this problem occurred, i checked for vacuum leaks on the inlet and cured some, that may be the start of the problem.

[johnbuckley]

The carbs have a small air passage in the top casting and (after about mid 1930)a larger one at the top of the bowl in the lower casting; so no vaccuum or pressurisation is going to develop to cause the problem you described.