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Oil leaking from Sniffle Valve

Aussieflyer

Active Member
My aircraft has now flown 110 hrs and I have changed my oil from
Mineral oil to Shell 100W 5 hours ago.
( Vans supplied IO-390 )

I am now getting oil dripping on the floor from the Sniffle Valve.
This is approximately the same amount I was getting when I tried to change from Mineral oil to 100W at 50 hrs, I was advised then to put the mineral oil back in and run for another 50 hrs.
Oil consumption while running on Mineral oil is approx 2 qts every 25 hrs and no dripping at all from Sniffle Valve.

Why does this happen when I change the oil ?

Can anyone advise what action I can take ?


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I am still getting oil (mixed with fuel) from my sniffle valve after 600+ hours. I bought my engine new from Lycoming and called them a number of times on this to understand it. At the end, they assured me that there is nothing wrong with the engine and ask to continue using it. They never asked me to change back to mineral. The engine has been running really great, no problem at all thus far.
 
sniffel valve

I am seeing the same. A small amount of oil/fuel mixture after shutdown. Engine has 76 hours on the 390 and oil consumption is stable at 1qt every 10 hrs.
 
Just another data point - I consistently get fuel drops from the sniffle valve. Sometimes just fuel, sometimes some oil mixed as well. Just switched to detergent oil (Aeroshell W100) at 60 hours - now at about 70 hours. I am using about a quart in 15-20 hours. Engine is a Superior XP400.
 
For the first couple of engine runs after first start, I got a mixture of fuel and oil and since then, it's just been pure fuel after each shutdown.
 
Just to add a bit more info that I add about a Qt. every 10 hours and has been consistent since the beginning.
 
I had similar symptoms.

I have an injected M1B and did not place the sniffle valve. This past year I had persistent oil in the sump noted on scoping. If I had a sniffle valve, it would have been leaking similar to yours. I ended up finding a casting crack in the sump allowing a small amount of oil to trickle into the sump. It was more noticeable after switching to a thinner multiweight oil. Although this is an uncommon problem, remember it if you do not find any other cause.

This was written up in a different thread.

Good luck
 
Sniffle valve seals off so it does not permit air to be sucked into the intake manifold through the little valve when the engine is running and is open to drain the intake of residual fuel (usually from injector leak down) and oil leaked past the intake valve guides when the engine is not running. If the sniffle
valve is eliminated there is a small chance of sucking these residual liquids into the cylinders and "hydro locking" the engine (bending or even breaking the rods).
 
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I have a new 390 with about 120 hours on it, and in the beginning, had the same drip issue. It has been decreasing, but still happens a bit. This engine replaced a 360, which went the way of a cracked case, but never leaked at the sniffle valve, so the behavior of the new engine was a bit of a surprise. The fuel component is not just injector leak down, it is also any amount of flooding, and then any amount of oil with it makes a mess.

The way I solved it was to run the sniffle valve hose into a little bottle, made from a spice container, so it doesn't end up on the floor and nose gear leg. It takes forever for any significant amount to accumulate, so you can easily dump it at annual time, or oil changes.

Reinhard Metz
 
Sniffle Valve Install

Am I suppose to let all the oil drain out of the hole the sniffle value goes into before installing the sniffle valve?

I'm installing Sniffle valve now in new Lycoming IO360. When I remove the plug oil drains out. Am I suppose to let all the oil drain out of the hole the sniffle value goes into? Is the oil coming out the same as crank case oil? Is this the same compartment? Would all the oil eventually drain out of engine if I left out the sniffle valve?

Thanks
 
Am I suppose to let all the oil drain out of the hole the sniffle value goes into before installing the sniffle valve?

I'm installing Sniffle valve now in new Lycoming IO360. When I remove the plug oil drains out. Am I suppose to let all the oil drain out of the hole the sniffle value goes into? Is the oil coming out the same as crank case oil? Is this the same compartment? Would all the oil eventually drain out of engine if I left out the sniffle valve?

Thanks

Steve, the purpose of the sniffle valve is to drain liquids from the intake plenum...oil and/or fuel under normal circumstances, and water if you get a load down the air intake while parked in the rain. So yes, if there are liquids in the plenum, they will drain. Shake the valve. Hear the little check ball? It sucks upward and seals the drain when the engine is running at a manifold pressure less than ambient.
 
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