Oil & Fuel Gas in my Oil.

[ldabe]

What can cause gas to be IN the Oil?

I have a PT 422, with a gas shut off valve between gas tank and carb that I installed years ago when I bought the PT used.
The carb fuel solenoid valve ($$$) failed so I cut the tip off, disconnect the DC volt wire and had run the PT for the season that way.

At end of last year when starting the PT it began to "regurgitate" fluid (I made a topic/thread on that) out of the Breather Hose connected under the Cleaner Base (aluminum plate setting on top of carb).

I have begun to work on this beast again (luckily I am not in need of this beast very often right now).

So, where is the gas getting into the oil?
Would it be going past the Needle that is part of the Float?

Scratching my head! Love the PT422 when it is running

 

[flyerdan]

If it has a mechanical fuel pump I'd strongly suspect it has a flaw in the diaphragm that's allowing fuel into the crankcase. It can have a small tear that still allows it to make enough pressure to keep the engine running.

 

[m5040]

If it isn't the fuel pump diaphram, then it could be the carb needle/seat leaking 24-7 due to the fuel tank being higher then the engine. Just a drip would cause the intake to flood eventually making its way into a cylinder, leaking past the piston rings into the crankcase. VERY BAD CONDITION.

You could change the oil/filter then shut off that valve EVERY time you shut it down and check to see if the oil level goes up. If it does it is the fuel pump diaphram.

 

[larrydman]

I slightly overfilled my engine oil one time and started getting gas in my oil. I drained and replaced the oil and never had any more problem. I just figured it was because of these slopes I'm always on caused it. I was more careful from then on about proper oil level.

 

[ldabe]

Thanks guys, I will take all that you said in consideration.
I have drained all the oil, and will change the filter and refill the oil.

I am wondering if I should go ahead and change the needle and seat, I don't think that those parts are very expensive, and I think I can get them at the NAPA or Mom/Pop small engine shop.

Hopefully the fuel pump is still good.

 

[m5040]

In my opinion, the needle and seat is not 100% effective 100% of the time. That is why the manufacturer spent the money to put in the electric fuel shutoff. If you want to cut corners, just shut off the valve you installed and check your oil often until you make sure the fuel pump is not leaking internally.

 

[ldabe]

In my opinion, the needle and seat is not 100% effective 100% of the time. That is why the manufacturer spent the money to put in the electric fuel shutoff. If you want to cut corners, just shut off the valve you installed and check your oil often until you make sure the fuel pump is not leaking internally.

m5040, That is my plan, to shut off the gas shut off valve that I installed years ago (though I thought I shut it off every time I shut the engine down) and check the oil to see if gas migrated, each time I shut the PT down.

I have been told that
1) the electric fuel shutoff "solenoid" is to prevent backfire by one small engine parts place.
Then I was told that
2) the electric fuel shutoff "solenoid" is to stop the gas flow and "must" be operational, by another small engine parts place.

Which is right?

If the carb needle is in the seat properly, and the electric fuel shutoff solenoid is disconnected with plunger cut off, and the fuel pump is working properly, and then when the engine is shut down and I turn off the fuel shutoff valve, will there still be a possibility of gas migrating into the oil?

Also, does anyone know of an alternative than ordering from Power Trac, or Robin/Subaru for a "needle & seat"?

 

[MossRoad]

Any small engine shop that services Robin should be able to get you the needle and seat.

Also, many on-line sources.

 

[m5040]

"Which is right?

If the carb needle is in the seat properly, and the electric fuel shutoff solenoid is disconnected with plunger cut off, and the fuel pump is working properly, and then when the engine is shut down and I turn off the fuel shutoff valve, will there still be a possibility of gas migrating into the oil?

Also, does anyone know of an alternative than ordering from Power Trac, or Robin/Subaru for a "needle & seat"? "

As I stated, the needle/seat can leak. It was never intended for a gravity feed situation with constant supply and no consumption (engine off). The only thing that closes the needle is the force of the carburetor float, floating on the gasoline and pushing the needle into the seat. Any small defect in the needle/seat can cause a leak and with gravity feed, that can empty the entire fuel tank! Even the cost conscience Henry Ford put shut off valves on the model T and A's of the 20s and 30s.
When the fuel tank is above the carb, they use a second fuel shut off, not a option.
If you shut off the manual valve, there is no way for the gas to leak/migrate into the engine.
For alternate parts source, look at who makes the carburetor, and do searches from there. There are 2 types of seats (at least there used to be), a solid brass needle or a soft rubber needle (like a Viton composition) that seats better. I liked the Viton.
I don't see anyway that a electric fuel shut off can stop a backfire out the carb. Even when you shut off the valve (manual or elect), the engine will run for a few min to use up the gas in the carb.

 

[ldabe]

UGGH!!!
I drained and changed my oil. Installed new spark plugs. Cleaned carb. Put a new needle valve in (connected to float in carb...$26!!!).
Cranked the engine, let it run, ran pretty good, turned off gas cock, let fuel burn off in carb and engine to stop.

Let it sit a couple a of days, came into my garage and SMELLED GAS!

Looked to be a cracked fuel line tube connected to Fuel Pump, except it was the vacuum line!
Took the line off and gas flowed out. Pulled the Oil Dip Stick, and gas came flowing out!!

So, I bought a new Fuel Pump, which I have not installed yet. I am thinking it must be a bad Fuel Pump, but before I put the new on, I thought would get some feed back from you guys on here, since as I have stated in the past, I am not much of a mechanic and don't really know how engines work.

There was about 6 ounces of gas that came out of the vacuum line and the Oil Dip Stick hole (I have not drained the oil and replaced it yet).

Before I install the new Fuel Pump, is there another possibility of how gas is getting into the Oil?

Thanks in advance for any help on this.