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Handy Tips To Solve Carburetor Problems
If plugged or overflowing carburetors are a problem in your seldom-used older tractors, Dale McLaen has some suggestions. Over his 27 years of repairing all types of farm engines in his on-farm shop, he has cleaned and used carb kit parts to refurbish dozens of updraft carburetors. He blames most of the problems he has seen on poor-quality fuel and modern carb kits.
  “I’ve learned to make modifications that can reduce carb problems,” says McLaen. “I said reduce, not eliminate them, as it’s nearly impossible to fix these problems forever.”
  McLaen grew up driving gasoline-powered tractors in the 60’s and 70’s without ever installing a carb kit. The only time he shut off the fuel line was to clean the sediment bowl. That’s no longer the case.
  “Modern reformulated fuel quickly turns to stinky, sticky varnish if it sits too long,” says McLaen. “Tractors that once burned hundreds of gallons of fuel each season may only burn a tank or so a year. The result is gummed up and overflowing carburetors.”
  Another problem with fuel, he notes, is the addition of ethanol. While he uses E10 in everything he drives, he does not use it in equipment that may sit idle for months.
  “Alcohol absorbs moisture, making the reformulated fuel problem worse,” says McLaen. “It also contributes to rusting the inside of fuel tanks.”
  Carb kits are another problem, even new ones. “I recently put kits in carbs on A, C, H, and 300 IH tractors,” says McLaen. “Three of the four carbs overflowed and leaked fuel on the floor within a day, and the fourth did so within a week.”
  While he could make the problem better, he couldn’t fix it. He blames the Viton tipped needles found in today’s carb kits.
  “The Viton tips should be better, but they just don’t seal as reliably in a carburetor with constant fuel pressure present in a gravity-type fuel supply,” says McLaen. “To prove my theory, I found a brass needle in my spare carb parts and installed it in the H carb. Problem solved.”
  McLaen says OEM-type brass needles tended to seal better when new and could be easily cleaned and reused. If one seeped, a tiny amount of polishing compound on the tip and twirling the tip against the seat sealed the surface.
  One solution to the overflow problem is to manually shut off the fuel line every time the engine is turned off. A one-time fix is to install an electric fuel shut-off solenoid ($15 online) in the fuel line. This automatically shuts off the fuel line when the ignition is turned off.
  Recently McLaen ran into another carburetor problem. The inlet portion of the carb on his 300 IH had a drain with a felt filter plug intended to allow any overflow to drip out. It plugged up after 60 years, causing overflow fuel to puddle in the inlet hose.
  “I removed the plug and installed a 1/4-in. hose barb fitting and attached a short section of hose and a small filter on its end,” says McLaen. “The filter is simply to prevent any dirty air from being sucked back into the air inlet when the engine is running. I also replaced the fuel bowl drain plug with a brass petcock drain valve, so I can easily empty the carb if needed or check to see if fuel is reaching the carb properly.
  “You might not be able to do this on some carbs,” says McLaen. “However, the general idea is to manage a leaky carb rather than have it drip uncontrollably and be a fire hazard.”
  Contact: FARM SHOW Followup, Dale McLaen, 13756 Hwy 11, Rutland, N.D. 58067 (ph 701-678-5232).

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2023 - Volume #47, Issue #6