Debris on Valves?

[JohnSBA]

Yesterday an IA who was cleaning/gapping the spark plugs in an 0360 told me it's important to take a bent-end pick and clean out the threads in the head. After doing that, he blows compressed air into the hole before re-installing each plug. He says any remaining debris is blown out by the engine. His thesis seems to be that the operating velocities and temperatures are such that there's no way anything can remain trapped at the metal to metal valve seat contact point. Question: Might this lead to a bit of debris lodging between a valve and face, in turn leading to eventual failure of that valve?

 

[N801BH]

Yesterday an IA who was cleaning/gapping the spark plugs in an 0360 told me it's important to take a bent-end pick and clean out the threads in the head. After doing that, he blows compressed air into the hole before re-installing each plug. He says any remaining debris is blown out by the engine. His thesis seems to be that the operating velocities and temperatures are such that there's no way anything can remain trapped at the metal to metal valve seat contact point. Question: Might this lead to a bit of debris lodging between a valve and face, in turn leading to eventual failure of that valve?

I would be more concerned it falls into the area between the cylinder wall and the top edge of the piston just above the ring.. In reality it will probably get blown out as soon as the motor lights off, but, the slight potential of it slightly scoring the cylinder wall is real. IMHO.

Ben.

 

[jhausch]

Sounds like a neat product opportunity. A thread-chaser tap with a bore down the middle and some cross-drilled holes and a venturi type fitting on top. As you thread it in the hole it cleans the threads and the venturi on the outside (hooked to shop-air) pulls out the debris.

 

[Dan Thomas]

I sometimes clean out the deposits from the plug holes. If there's enough of it in the lower holes it melts and runs into the plug and fouls it. Compressed air gets it out, and it's even better if air is being blown gently into one hole while it's being picked out of the other; none of it gets into the cylinder that way. It's not really hard and won't stick to the valve or seat faces and we've never had scored cylinders from it. There's more junk getting through the lousy air cleaners on light airplanes, especially in operation on dusty days or gravel/dirt strips. Most of the airboxes have big gaps everywhere and the filters let fine stuff through. The average cheapo car has a better cleaner. Silica, the chief component of sand and dust, is extrememly hard stuff and can eat an engine up in short order.

Dan