Oil Dripping Down from Sniffle Valve

[jbrrapa]

Oil Dripping Down from Sniffle Valve


I recently had two TSIO-360 cylinders overhauled. The cylinders were factory new with only about 150 hours, but that’s another story.


The two cylinders now have approximately 14 hours since the overhaul. After each flight, a mixture of avgas and mostly oil drips from the sniffle valve. The engine shop says it is not worrisome and it will soon stop. Not only has it not stopped, it has remained the same or gotten slightly worse.


A picture is attached showing the pool on the hangar floor three days after a recent flight.


Any thoughts on the cause or solution?

 

[Tom-D]

Sniffle valve
Description. Sniffle valve provides automatic drain of overflow fuel from the sump and closes when engine is running. Necessary only on horizontal induction fuel- injected Lycoming engines.

 

[jbrrapa]

Sniffle valve
Description. Sniffle valve provides automatic drain of overflow fuel from the sump and closes when engine is running. Necessary only on horizontal induction fuel- injected Lycoming engines.

It is standard equipment on the Seneca II which has TSIO-360 engines. I believe that it is normal for a small amount of fuel to drip from the valve after engine shutdown. I don;t believe that the oil dripping is normal. The oil dripping began concurrently with flights subsequent to the installation of the two overhauled cylinders.

 

[Checkout_my_Six]

You have some worn intake valve guides. Bet the offending cylinders has oil foiled plugs on the the lower plug and it uses more oil than usual.

 

[Stewartb]

My IO-390 does the same occasionally. I swapped the Lycoming induction for Superior and know for certain the induction was squeeky clean when I put it on. I'm not concerned. FWIW the Lycoming induction had lots of oil in it when I removed it. And Lycoming had run it for 70 minutes on a test stand.

 

[jbrrapa]

You have some worn intake valve guides. Bet the offending cylinders has oil foiled plugs on the the lower plug and it uses more oil than usual.

The 8130-3 indicates that new intake valve guide seals were installed when the cylinders were overhauled. If those seals are either defective or improperly installed, can they be changed without removing the cylinder?

 

[Checkout_my_Six]

The 8130-3 indicates that new intake valve guide seals were installed when the cylinders were overhauled. If those seals are either defective or improperly installed, can they be changed without removing the cylinder?

Also, if they forgot to replace or install the intake valve guide seals....it would leak or use oil.

Yes, the seals can be replaced without removing the cylinder.

 

[Doug Reid]

The sniffle valve is doing its job.

 

[Stewartb]

Your sniffle allows liquid to drain from the induction in the absence of vacuum, so when the engine is off. The purpose is to drain fuel that slipped through open intake valves during priming. One would think much of that fuel would evaporate and make it's way into the combustion process. Probably does, too, until it mixes with a little oil. I never see any raw fuel drain out. Only a mixture of fuel and oil, and if not for the blue dye I wouldn't know there had been fuel present.