I have a Craftsman 17HP tractor with a Kohler CV490S engine. The carburetor is a Walbro 12053118. The engine has worked fine for the past 3 years, but this fall, the carb has started leaking fuel. If the tractor sits a day or two, the carb leaks fuel into the piston chamber. If it sits long enough, tractor is hard to start, and fuel comes spraying out the exhaust.

I've rebuilt the carb with a kit, replacing the needle valve, float, and the solenoid stopper, and cleaned the whole thing with carb cleaner. I've drained the tank and flushed it and the fuel lines. I've replaced the fuel filter. The carb still leaks fuel. The carb kit came with a rubber needle valve seat, but when i rebuilt the carb, it looked like my carb didn't use one (it just has a brass seat). From what I can tell, the seat doesn't look worn or scratched. Holding the float up, the needle valve seems to seal tight enough if I test it by blowing in the inlet. The seat is pressed in, not screwed in.

Other than buying a fuel shut-off valve and installing in right before the carb, or buying a new carb, does anyone have any ideas?

 

Get a few Q-tips and a tub of turtle wax rubbing compound (made for shining up chrome on cars). Dip an end of a Q-tip in the rubbing compound, put the other end in a drill, and spin the Q-tip in the seat area where the needle goes to polish up the seat. Sometimes a little scar or bit of corrosion in there causes it to leak, and this is the only effective way I've found of fixing it. Sometimes replacement is about the only option, but this trick usually works. Make sure to use a few clean Q-tips soaked with carb cleaner to clean out the seat after using the rubbing compound.

 

Walbro Carb leaking fuel in oil when off.

By jim3722 » Wed Sep 01, 2010 7:04 am

Kohler Carb # 12-853-118-S, CV490S Spec.# 27532 is the same Carb as Walbro LMK-95A.

The Carb Kit to repair this problem is # 12-521-03-S. The Kit come with a Brass Seat, Tools and instructions on how to replace the seat. This Kit was made available in late 2009. Kit price is about $28.00 dollars.


This kit also contains everything in kit # 12-757-03-S.

A Service Bulletin was sent to all Kohler Dealer to use Kit Number# 12-521-03-S for Carbs with brass seats.


To verify this information contact.

Nathaniel Vlietstra

Small Engines Specialist
Field Service Group
Kohler Engines
444 Highland Dr. Kohler WI 53044
920-457-4441
jim3722