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Leaky carb


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#1 David Brown OFFLINE  

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Posted October 31, 2016 - 06:58 PM

I have a brand new carburetor on a k321 that leaks something awful. Never had gas in it before I put it on this tractor. I noticed that the gasket around the bowl was a bit too big to set in the groove so I got a new one and tried it out. It still leaked so I went on to adjust the float. If anything, the float sits low enough that gas shouldn't even get high enough for it to run but run it does while leaking. The float, although a little dinged up, does not appear to take on gas and everything with the needle valve is clean. What could this possibly be?

#2 shorty OFFLINE  

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Posted October 31, 2016 - 07:06 PM

Fuel pump or gravity flow?
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#3 Bolens 1000 ONLINE  

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Posted October 31, 2016 - 07:10 PM

Is this a new, NOS or aftermarket carb?

Also Fuel pump or no fuel pump?


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#4 EricFromPa OFFLINE  

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Posted October 31, 2016 - 07:18 PM

Check the rubber tip on the float needle if it's a Carter/Kohler carb and if it's a Walbro change out the rubber needle seat.

Both get hard as a rock over time doesn't matter if it was a NOS carb or not.Small rubber pieces deteriorate quickly even sitting on a shelf for a few years.

Just like Car tires dry rot if stored for a couple years.

 

Take the float back out and give it a real good Shake.If it's leaking you will be able to hear and feel the gas inside of it sloshing around.If you feel Anything inside of it than the float is shot.

 

I have re-soldered seams on floats before but it's better if you just replace it with a new one.


Edited by EricFromPa, October 31, 2016 - 07:24 PM.

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#5 David Brown OFFLINE  

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Posted October 31, 2016 - 08:33 PM

It does have a fuel pump and I believe this is a NOS carb. It's even adjustable. I did shake the float and it was quiet. I was leaning toward the rubber tip. Also I noticed it doesn't swivel real free. I just wonder if it's getting hung up.

#6 Bruce Dorsi ONLINE  

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Posted October 31, 2016 - 08:40 PM

Also I noticed it doesn't swivel real free. I just wonder if it's getting hung up.

 

That's a strong possibility.


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#7 karel OFFLINE  

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Posted November 01, 2016 - 08:05 AM

Check the rubber tip on the float needle if it's a Carter/Kohler carb and if it's a Walbro change out the rubber needle seat.

Both get hard as a rock over time doesn't matter if it was a NOS carb or not.Small rubber pieces deteriorate quickly even sitting on a shelf for a few years.

Just like Car tires dry rot if stored for a couple years.

 

Take the float back out and give it a real good Shake.If it's leaking you will be able to hear and feel the gas inside of it sloshing around.If you feel Anything inside of it than the float is shot.

 

I have re-soldered seams on floats before but it's better if you just replace it with a new one.

Dosesn't re-soldering kinda change the weight of the float? I have thought of doing it before, but have not, because of that thought.



#8 EricFromPa OFFLINE  

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Posted November 01, 2016 - 07:45 PM

Depends if you clean it up afterwards and don't just glob the solder on it.I use a fine Silver solder with plenty of flux.If you solder 1 spot and the heat makes another hole on the seam you might as well heat the whole thing up and take it apart and wick up the old solder.Then use silver solder paste to solder it back together.

 

Silver solder paste is ground up silver lead and tin solder suspended in flux.It flows and sticks better than anything I have used.

 

I went to tech school for Electronics Repair just out of high school for 4 years so I have a good bit of experience soldering stuff lol.I had to take 3 classes so My other 2 classes were General Plumbing and Automotive Mechanic.I picked the stuff that I felt I would use the most but you can't do much with these newer and much much much smaller electronic components and my fingers don't work nearly as well as they used to lol.

 

I did manage to fix a free Samsung 50" Plasma TV with $20 worth of Ebay upgrade parts lol.1 small 8 pin voltage regulator chip,1 small 36 pin APU chip and 1 very small resistor.



#9 David Brown OFFLINE  

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Posted November 02, 2016 - 06:46 PM

I had a chance to revisit the leaky carb tonight and am more frustrated than I was before.  It's important to note here that the carb leaks because it's getting too much fuel in the bowl.  It does not leak around the gasket, at least not now.  Here's what I did/found:

 

Adjusted the float to the point where the engine shouldn't be able to get fuel, still leaked.

Pivot was rough so I made sure that was all good, still leaked.

Took it apart.  Shook float, dry.  Checked rubber tip on needle, soft and seemed perfect.  Put it back together, still leaked.

Tried another float from a carb that worked (it was sucking air), still leaked.

 

 I gotta tell ya, I'm getting very tired of taking this carb off and putting it back on.  This whole thing makes no sense.  Never have I had a kohler carb that leaked like this.  It's puzzling.  Tractor runs great with it on, it just leaks onto the exhaust.  Not good.  I want to loan this tractor out to my nephew for snow removal but I need to make sure it's right.



#10 Alc ONLINE  

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Posted November 02, 2016 - 07:48 PM

I would take the bowel off , carb in normal position ,attach a hose to the inlet , blow with your mouth and gently raise the float with your finger to see if it seals tight and where it compared to the specs.
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#11 David Brown OFFLINE  

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Posted November 02, 2016 - 08:02 PM

I would take the bowel off , carb in normal position ,attach a hose to the inlet , blow with your mouth and gently raise the float with your finger to see if it seals tight and where it compared to the specs.

Good idea, thanks.  I'll try that next.  You know, I just thought of what this could be.  Correct me if I'm wrong but shouldn't there be a rubber piece up in where the needle seats?  This carb doesn't have one and I'm not entirely sure that all of them do.  I think that would solve the problem.



#12 Bruce Dorsi ONLINE  

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Posted November 02, 2016 - 08:04 PM

I have a brand new carburetor on a k321 that leaks something awful.

Never had gas in it before I put it on this tractor.

What could this possibly be?

 

Can you determine where the gas is leaking from?

 

A brand new carb may have a flaw in it.  ....It could be a cracked or porous casting, or a machining error. 

 

Is the float bowl bent or distorted ?  ...Is the top edge of the bowl even and contacting the carb body all the way around?

 

If the fuel were flowing past a stuck-open float-valve, the engine would probably flood, or at least run very rich. 


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#13 Bruce Dorsi ONLINE  

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Posted November 02, 2016 - 08:12 PM

Correct me if I'm wrong but shouldn't there be a rubber piece up in where the needle seats?  This carb doesn't have one and I'm not entirely sure that all of them do.

 

If the float needle has a soft tip, there would not be a soft seat in the carb body.

 

Some carbs use a float needle without a soft tip.  .....These may, or may not, have a soft seat in the carb body. 

 

Some carbs have a removable brass float valve seat.  ....These require a gasket to seal where they screw into the carb body, as it is possible for gas to leak into the bowl, even though the needle may be seated.


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#14 secondtry ONLINE  

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Posted November 02, 2016 - 09:02 PM

   If you turn the carb upside down with the float bowl off, needle, seat, and float installed  normally and use the fuel line to blow through the inlet the weight of the float on the needle should keep it sealed. If not you need to inspect the needle and seat very carefully until you find the problem.   Don     


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#15 Alc ONLINE  

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Posted November 03, 2016 - 05:20 AM

Some carbs have a removable brass float valve seat.  ....These require a gasket to seal where they screw into the carb body, as it is possible for gas to leak into the bowl, even though the needle may be seated

 

Never thought of a gasket above a removable seat !!!! 






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