B&S 21HP Gas in crankcase

dlmcmurr · Jun 1, 2016

When cleaning out the Nikki carb on this engine, I made a stupid mistake and misinstalled the fuel inlet o-ring. Over a few days time it filled the cylinder and crankcase with gasoline. The dipstick shows about an inch above the level the day before I worked on it.

I know now how to properly assemble the carb, but my question is what should I do prior to running the engine again other than changing the oil and filter?

Thanks in advance,
Dave

Pumper54 · Jun 1, 2016

I don't know anything about that engine but based on my years of riding motorcycles and having seen that happen before when people don't turn off the fuel valve I would change the oil and filter and then pull the plugs and if you can, crank the engine over slowly to spit out any gas in the cylinders. New plugs, fresh oil and gas and you should be ready to go.
Tom

bertsmobile1 · Jun 1, 2016

:welcome:
Remove the spark plug and clamp it well away from the plug hole as the escaping fuel can ignite.
I earth out the coil and remove the hood , just in case.
drain the oil and refill with sheap supermarket oil
crank over the engine a lot till no more fuel blows out
squirt a little oil down the plug hole, turn the engine over by habd a few times to distribute the oil then crank the engine to expell the excess oil.
Replace the plug and start the engine.
let it run about 15 to 30 minutes then dump the oil ( which is why you use cheap oil )
fill the engine with the cheap oil and repeat.
If the drained oil smells clean ( no fuel ) refil with mower oil.
I fit a tap to the fuel line on every mower I service and encourage customers to use it every they finish mowing .

dlmcmurr · Jun 1, 2016

Following your instructions, I wonder if it's okay to not replace the oil filter until I put in the good oil?

Thanks to you and pumper54 for the quick replies.

Dave

bertsmobile1 · Jun 2, 2016

dlmcmurr said:
Following your instructions, I wonder if it's okay to not replace the oil filter until I put in the good oil?

Thanks to you and pumper54 for the quick replies.

Dave

Remove it and let it drain out overnight then refit for the cleaning cycle and when you are done fit a nice new one.

deano77 · Jun 2, 2016

i like to put a6$ fuel shutoff in thhe fuel line most dont have one the oring always distorts usually flat on 1 side youtube has several videos

dlmcmurr · Jun 2, 2016

deano77,

I have to agree with you. It will have a shutoff like the old Wheel Horse I used to use back in the early 80s. I would always turn it off when parking it for the day.

As I'm putting together my parts order, I have a question about the float. Should it look like the older, adjustable floats where the top edge of the float and the carb flange are parallel when the assembly is inverted? Mine goes down much farther toward the flange. If my intuition is correct, I'll just go with a carb kit that includes a float, pin, needle valve, and fuel transfer tube rather than just the cheaper o-ring set.

Thanks to everyone,
Dave

dlmcmurr · Jun 9, 2016

Thanks to everyone for the suggestions. I bought a carb kit off ebay which included included the float, needle valve, and transfer tube; it wasn't the simplest to reassemble as the fuel inlet o-ring was kinda snug as I was trying to keep that complicated bowl o-ring in place. Also replaced the magneto while I was down to it where a rat had eaten the insulation and part of the conductor off the spark plug wire, as well as replaced the fuel filter and added a fuel shutoff.

Completed the first two oil changes and she's purring like a kitten. Just need to do the final oil and filter change and put on new blades and I'm ready to go again. All told, I've spent less than $100 on everything, so I'm definitely well pleased.

Thanks again,
Dave

bertsmobile1 · Jun 9, 2016

And on the subject of kittens, get one for the shed.
Feed it 1/2 of what the pet food makers recommend , in the morning before you go to work so it will be hungry all night and keep it in the shed overnight.
Shed cats solve the rodent hotel problem .

B&S 21HP Gas in crankcase

More options

dlmcmurr

Forum Newbie

Pumper54

Well-Known Member

bertsmobile1

Lawn Royalty

dlmcmurr

Forum Newbie

bertsmobile1

Lawn Royalty

deano77

Member

dlmcmurr

Forum Newbie

dlmcmurr

Forum Newbie

bertsmobile1

Lawn Royalty

Footer Links 1

Footer Links 2