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Leaking Carb on Sears Suburban 15


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#1 StinkinLincoln OFFLINE  

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Posted May 17, 2018 - 12:38 PM

Can anyone tell me what would cause the carb to leak from this spot?

leak carb.jpg


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#2 Bolens 1000 ONLINE  

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Posted May 17, 2018 - 12:44 PM

Only thing that controls the flow of fuel is your needle and seat, if its leaking there your float is set too high or faulty needle/seat the gas is getting above the proper fill line and leaking down


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#3 StinkinLincoln OFFLINE  

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Posted May 17, 2018 - 01:00 PM

Should I try to adjust the needle valve? Or take off the bowl and adjust the float somehow? Is there a source for parts to rebuild or should I be looking at a replacement?


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#4 WNYTractorTinkerer ONLINE  

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Posted May 17, 2018 - 01:13 PM

Also the float could have a hole so it won't close the needle/seat..  

 

BTW-  Pull out the main jet before you tear into this carb..  (nut/screw on the lower left side.)  

 

You can thank me later..


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#5 Bolens 1000 ONLINE  

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Posted May 17, 2018 - 04:48 PM

^^^  Ditto center main nozzle must come out before you pull the halves apart

 

I stock rebuild kits for these if needed and also can supply new OEM briggs carbs but my guess is you can fix this one pretty easily

There is a manual section here and it has the out of production briggs repair manual for engines made 1919-1981 it will have some good references for you to follow



#6 EricFromPa ONLINE  

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Posted May 17, 2018 - 05:09 PM

Only thing that controls the flow of fuel is your needle and seat, if its leaking there your float is set too high or faulty needle/seat the gas is getting above the proper fill line and leaking down

 

Actually the float and needle is usually the last thing that will make the carb leak on the Large 2 piece flow jet carbs. 80% of the time it's either the Emulsion tube or the intake valve.

 

If the Emulsion Tube isn't tight or properly seated, it will leak. Gas will run down the hole in the bottom of the bowl and rite up beside the Emulsion tube and dump rite into the throat of the carb because it's lower than the float needle if the emulsion tube it's not seating and sealing the hole up.  They can actually start a siphon and drain a whole tank of fuel.  

 

Even a brand new OEM or NOS Briggs carb will leak rite out of the box.  I've used a drill bit ran backwards to touch up the mating surface up inside the carb with great success. It polishes the seat but doesn't cut into it.

 

 

If the intake valve isn't seating properly (burnt valve, valve lash to tight, or heavy carbon deposits around the valves) it will pressurize the float bowl in the carburetor and it will leak gas out of every tiny crack and hole. Easy way to tell if it's a valve problem. The carb will leak and it will be wet around the throttle shaft and choke shaft.

 

Check these 2 videos out. They helped me fix a few old 2 piece flow jet carbs. Mr Varga had a problem with one carb that would not stop leaking no matter what he did and I suggested for him to lap the intake valve in and check the tappet clearance. He lapped both valves and had to grind a bit off of the intake valve stem to get the clearance set. The carb stopped leaking and the engine ran very very good afterwards.

 

 


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#7 EricFromPa ONLINE  

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Posted May 17, 2018 - 05:20 PM

Very Very Important step:

Make sure that you grind off the shoulders on the screw driver. You do Not want the screw driver to come in contact with the aluminum threads. 1 nick or scratch and you will have serious problems. The brass tube will cross thread in the aluminum and Gaul fast.

 

 

Good thing to pull the carb apart and clean it really good anyway so check the float and make sure it doesn't have a hole in it. Pull the float out and shake it. You will hear Gas sloshing around inside of it if there is a hole.

 

Set the float level dead even with the carb body then tweak it down towards the carb body just a hair. If the float is dead even I found that they will run a bit to lean on hills.


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#8 Lmiller3358 OFFLINE  

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Posted May 17, 2018 - 06:51 PM

I bought a 1/4 inch flat head screw driver a few years ago at the True Value Hardware store that works perfect for pulling out the main jet tube. I did grind just a whisker off both sides for extra measure. It's a straight shaft with no shoulders.


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