IH656 Fire Update

LaurenceA · Dec 24, 2014

Last month I posted a message about my IH656 catching on fire. Today we discovered that the crankcase was overfilled with a lot of gas mixed in with the oil. Doesn't make sense how the gas got in there. It'sFirst thoughts that someone sabotaged it. The tractor sits in a barn where we are away months at a time. Are we being paranoid or is there another way gas could find its way into the crankcase on its own? The fire appears to have poured our burning oil-gas mixture into the gravel drive below the crankcase vent on the left side. If the gas flooded the carb into the air intake hose it couldn't go far as the intake hose elbows up from the carb around 10".

Janicholson · Dec 24, 2014

Though seeming impossible, the situation is clearly an example of fuel filling the carb, the intake manifold, and, through an open intake valve into the cylinder/s. If the fuel in the tank is higher than the intake runner in the head, it will fill.
I have had it happen in a few hours. It was enough to hydrolock the cylinder with the fuel in it.
The engine would not turn. I pulled the plugs and (with the ignition off/disconnected) turned it over and purged the gasoline. The
yellowish white traces from the Idle screw indicates it was flooding and leaking from the screw. At least the engine was not ruined, and the building was not burned down. Jim

Curt Cooke · Dec 24, 2014

Bought a tractor this spring that had been sitting in a shed for a year or two. Spare you of all the details but the crankcase was full of gasoline that had leaked in there through the carb, manifold, valves and piston rings. Not expecting such a thing, it was quite exciting finding out. IT CAN (and does)HAPPEN!

Farmallhal · Dec 24, 2014

I believe when parking these older Farmalls with the gravity feed fuel systems it is best to shut off the tank valve when they are going to be parked or stored for a period of time, Hal.

504 · Dec 24, 2014

I shut the gas off as soon as I turn the key off. Gas and oil are too expensive to mix together.

used red MN · Dec 25, 2014

I almost posted that as a possible problem when I saw your first post. But I thought you would have said something about the engine running rich. The gas must have leaked out of the carb and intake after it raised to a high enough level to enter an intake valve. I have seen gassed up oil a few times on downdraft automotive engines with carbs. On an updraft tractor carb that happening is quite rare. In automotive type engines I've seen it blow off a valve cover or even distort the oil pan seal lip to where it would leak due an explosion in the crankcase.

LaurenceA · Dec 26, 2014

OK I now understand how the gas got into the crankcase. Was the long line of burning gas-oil mixture on the driveway just the excess fluid level pushed out of the crankcase vent tube?
I guess there are plenty of spark sources on that side of the engine that could ignite the gas vapors that aren't normally supposed to be there even though it discharges below the engine.

Cory Schmidt · Dec 26, 2014

I would think so. The push rods are on the inside of that cover(that the vent is on). They act like pumps and lift some oil up to the rockers while lubricating the rod guides. If enough fluid built up behind the cover, the fluid could run out the vent. There is only a mesh in the tube to keep dirt/bugs out of the engine

IH656 Fire Update

LaurenceA

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Janicholson

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Curt Cooke

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Farmallhal

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504

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used red MN

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LaurenceA

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Cory Schmidt

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