Gas in oil

i have a John deer D130 with B & S engine. accidentally put diesel in tanks. needless to say it did not work well. Had some serious backfires. Drained the diesel ad put in gas. since that time it is filling the crank case with oil. Carb does not appear damaged i thought i may have damaged engine (still could be) but it seems to do ok with a gravity feed tank. replaced fuel pump and checked pvc valve (seems good). When i hook fuel line up to tank and cut grass about thirty minutes to an our the oil level is high and smells like gas. Cant seem to find anything wrong and im a pretty good mechanic. will high blow by cause the fuel pump to pump to hard an force gas past carb ? it seems like gas is finding another path into crankcase. The mower does not seem to be way rich. Help please

Needle and seat are stuck open allowing gas to go through the carb and past the valves or piston and into the oil.

BlazNT is correct on what he said about the carb......

I don't think you hurt your engine though... Diesel has oil in it and that's a good thing..... You said TANKS as in 2 tanks correct ????

I assume you have a OHV engine. 1 or a 2 cylinder engine doesn't matter in this situation.....

You also said that is does great on a separate gravity feed tank... That's a good thing also, but if you run the engine for a hour or so with the gravity feed tank will it fill the crankcase with gas ????

You have 1 of 2 issues with your engine.... 1st thing is Blaz is right on the needle and seat.. If you have a carb with a brass seat and the viton tips...Walbro carbs are known for that.... The gas is sucked up into the fuel pump and goes into the crankcase via the vaccum line that works the fuel pump... The Kholer engine carbs also do that...

2nd thing is a blown head gasket or 2 blown gaskets... The gas from the cylinder will pass the blown area and go into the valve rod valley and into the crankcase.........


Let us know Mon Ami ~!~!

And a perished fuel pump diaphragm can also allow fuel into the engine.
Run the engine for 5 minutes or so, wait a minute and remove the dip stick .
If smoke comes out that is a sign of a blown head gasket as is a bit of a bang and a puff of smoke when the governors allows the carb to open fully .

If the carb has allowed fuel to trickle into the cylinder while the engine is off you usually blow the head gasket when you crank the engine to start it...

Pull the impulse line off the fuel pump and check for fuel in the line.
It should have some oil vapour in there but no fuel.

After proper carb inspection & repair, I like to add an in-line gas shut-off valve. Just a lil extra insurance.

7394 said:

After proper carb inspection & repair, I like to add an in-line gas shut-off valve. Just a lil extra insurance.

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I do that all the time also a Briggs shut off is only 6 bucks, and great insurance..........

:thumbsup:

Chester1129!! said:

i have a John deer D130 with B & S engine. accidentally put diesel in tanks. needless to say it did not work well. Had some serious backfires. Drained the diesel ad put in gas. since that time it is filling the crank case with oil. Carb does not appear damaged i thought i may have damaged engine (still could be) but it seems to do ok with a gravity feed tank. replaced fuel pump and checked pvc valve (seems good). When i hook fuel line up to tank and cut grass about thirty minutes to an our the oil level is high and smells like gas. Cant seem to find anything wrong and im a pretty good mechanic. will high blow by cause the fuel pump to pump to hard an force gas past carb ? it seems like gas is finding another path into crankcase. The mower does not seem to be way rich. Help please

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Compression is good but not even 110 on one side 92 on other many have suggested a blown head gasket. very well could be because it back fired and knocked on the diesel. before i could get it shut down.

thanks to everyone that replied. ordering needle and seat. already replaced fuel pump (twice) I am also suspecting a blown head casket as many have sugested that is a possibility. when it tried to run on the diesel maybe to much pressure. compression is 110 in one cylinder and 92 in other. anyone know what normal is. thanks in advance.

I have seen people claim otherwise but I have never believed it is possible for a leaking float needle to flood the crankcase with gas WHILE the engine is running. The engine would puff black smoke stumbling until it died.

Walt Conner