Sniffer valve function

[scottmillhouse]

Working on FWF with my new IO-360 from Vans. Just installed the sniffer valve. When I pulled the plug to insert the valve about a cup of oil drained out. Engine is long term storage from Lycoming. Trying to figure out why there would be oil. This was the only plug in the area shown in plans. I guess I don't understand the valve's purpose. I though this valve was to drain excess fuel so I don't understand the oil.

[flyinga]

Oil is most likely to be from the long term storage procedure used by Lycoming. You are correct in your understanding or the valve; it drains fuel remaining in the intake system after shutdown.

[Bavafa]

Jim is absolutely correct but don't be surprised to see a bit of oil mixed with fuel after each shut down. It is a drop or two at most but most engines have a bit of oil mixed with the fuel. It is a nice add-on to the engine which helps drain any fuel in the sump when the engine is shut.

[BillL]

Originally Posted by scottmillhouse

Engine is long term storage from Lycoming. Trying to figure out why there would be oil.

Lycoming fills the cylinders with oil, it leaks pass the pistons (and out the intake valves as mentioned below). It is a horizontal engine. This is why you see guys pull the prop through radial a few times on the warbirds, to clear oil from the upside down cylinders that could result in hydraulic lock during starting. You will need to do the same before starting/spinning your engine for the first time. When you remove the exhaust port caps on the heads, or lower spark plug oil will come out of there too.

[KeithB]

I believe the oil in a cylinder comes out an open intake valve, runs down the intake pipe into the intake sump. When the plug comes out, so does the oil. It happened on my engine too - and boy is that pickling oil gooey.

During normal operation, the pressure in the fuel system bleeds off in the fuel servo and a small amount of fuel ends up in the intake sump, and drains out the sniffle valve. It has a bit of oil in the drainage, I would guess from the valve stems.

[mturnerb]

I had the same experience. I ended up putting a hose on the valve directed into a container. The oil continues to work its way down from the cylinders and out the valve.

[scottmillhouse]

That answers my questions so I now know this is normal. Wish I had the previous answer last night. Valve leaked a sticky oily mess onto my front tire over night. I now have a drain line connected to a container.

[maniago]

Mine is pickled as well, but havent put in a sniffle yet. But this begs the question: when in operation, should a hose be permanently connected to the sniffle so that whatever comes out doesnt drip on the inside of the cowl and stain/ruin the fiberglass over time?

[j-red]

I installed a hose back to the back of the cowl and out. Glad I did, because I accidentally flooded the engine during the first start attempt and plenty of gas came out of there. Definitely wouldn?t want that dripping into a hot cowl area.

[scottmillhouse]

FWF plans for IO show a drain line going to lower firewall