airtourer

Hi All,I have owned and operated an OS160 for a few years now, recently it is running hot to a point where it shuts down in flight. I have not changed fuels. Different plugs make no difference.The only thing I can think of is maybe the front bearing is leaking and sucking air causing the lean runs.Thanks if anyone can help.Paul

Scott Douglas

Mmm, sounds like one of the bearings are dying! If you turn it over by hand (when its cold) is it smooth or is there a rough feeling if you rotate it slowly? If so there's a bearing that needs replacing.

jetmech05

Richen it up some and see what happens. Mixture settings can need adjustment depending on atmospheric conditions.
If you adjust and it works then you're good to go

Bax

My Feedback: (11)

If the front bearing is leaking, it will not suck air. You will get fuel sprayed all over the aircraft. That's because the bearing does not seal the front of the engine. The seal is made by a thin oil film between the crankcase and crankshaft in the area between the carburetor and front bearing. The front bearing gets is lubrication from fuel that's forced forward by the pumping action of the crankcase. When the fit to the case and crank is eroded, too much fuel gets forced through the front bearing, usually spraying all over because of the rotation of the propeller. There's usually a small slot cut in the crankcase forward of the carburetor to suck excess fuel back into the crankcase during the intake portion of the engine's operating cycle.

If your engine used to run properly, but is now tending to run hot, it's obvious something has changed.

Has the compression been compromised by piston/ring/liner wear? Is the fuel system clean, leakproof, and free-flowing? Is the pressure port in the muffler blocked? Is the fuel in the tank getting air into it from vibration? Check the high-speed and low-speed mixture settings. And on and on. You need to go through the entire system (engine/airframe/fuel system) to debug the problem. Mount the engine on a test stand to see what may be going on.

jaka

Hi!
Perhaps I interpreted it wrong but it sounds as if Airtourer hasn't adjusted the high speed needle!?
Engines wears and after years of use you have to be prepered to change both cylinder liner and piston ...and ball berings.