Pull it through during preflight!!

[John B]

Today I went out to fly and performed my usual pre-flight. One item I always do is pull the prop through at least 4 compression strokes while noting the compression on each cylinder. Well today one cylinder felt weak. I won't bore you with the diagnostic details as that isn't the point of this post, but the cylinder head turned out to have a crack between the valve seats. Not uncommon. No flight today and have to order a new cylinder head tomorrow.

Point is that pulling through a complete cycle during preflight is a good idea if you don't already do it.

 

[Stinson Pilot]

That's always been a good practice. Good job!

 

[Speed20]

Today I went out to fly and performed my usual pre-flight. One item I always do is pull the prop through at least 4 compression strokes while noting the compression on each cylinder. Well today one cylinder felt weak. I won't bore you with the diagnostic details as that isn't the point of this post, but the cylinder head turned out to have a crack between the valve seats. Not uncommon. No flight today and have to order a new cylinder head tomorrow.

Point is that pulling through a complete cycle during preflight is a good idea if you don't already do it.

Great advice! Will always do that now! I’m over at JOT

 

[Aviacs]

Always treat the prop as hot, though.
One cold winter day i flew my C175 from FDK to State college, PA to meet a friend. After early dark that night he brought me back to the airport in the clear frigid weather. I untied the airplane, verified mags off, fuel off, and pulled the prop through to "loosen up the oil" before getting in to tax the battery starter.

You already guessed by now - an engine that was difficult to hand prop intentionally, started up immediately on first blade & i might not have survived if the friend had not stood by to see me off, and promptly jumped in front of the strut and leaned back.

I do know what i did wrong - light weight chocks in the baggage, but did not use them. Or leave tail tied. Complacency.
It is interesting how often many of us apparently discover bad P leads by exactly the same method.

smt

 

[bluerocket]

I have been told that if you pull your prop thru in reverse of it's normal rotation it will not fire. I have a high performance aircraft so don't pull it thru. I also spin the prop after running the fuel pump for 8 seconds or so with mags off for 1 full revolution before turning the key from off to both. the engine fires immediately The preferred starting procedure for my 1948 warbird

 

[Steve Stephenson]

If you have a live mag, it is less likely to fire the cylinder if rotation is backwards. It's not a guarantee though. The start method you describe uses the cylinder suction to prime the cylinders. Very effective. I have no electrical system on my Luscombe but do the same thing by hand before turning the left (impulse coupled) magneto on.

 

[shocktrooper]

Today I went out to fly and performed my usual pre-flight. One item I always do is pull the prop through at least 4 compression strokes while noting the compression on each cylinder. Well today one cylinder felt weak. I won't bore you with the diagnostic details as that isn't the point of this post, but the cylinder head turned out to have a crack between the valve seats. Not uncommon. No flight today and have to order a new cylinder head tomorrow.

Point is that pulling through a complete cycle during preflight is a good idea if you don't already do it.

Ya darn skippy! ..on that one. The avail Sonerai POH clearly advises to do this anyway...to; “ limber up the oil”...common sense proactive advice. I even do it any chance I get if it has sat unstarted for a week or more..it also excercises the mag’s impulse coupler and internal points device...keeps it all from taking a set during long term storage (like winter hibernation for you northern guys). Just my 2 cents.