sparkplug

Ok so I have a ZDZ 40RV which I am just starting to break in. Before I ran the engine it had very little leakage of compression when you turned the prop.

So I ran 24 Oz in the engine with a 32:1 fuel to oil mixture and now the compression is leaking quite a bit when you flip the prop slowly. You can hear it leak when you turn the prop.

Is this normal when you first start to break in these gas engines ?

Just a newbie with gas wanting to know if this is normal.

Enjoy!

deputydog

big difference between a dry cylinder and a wet one! No problems but it is best to break the engine in while flying. For gas you start on the ground to check your settings and then fly. Its not like a glow.

Diablo-RCU

My Feedback: (1)

Make sure that the spark plug is tight. Check it with a cold engine.

sparkplug

I checked the spark plug and it's tight but it still has that compression leak when you turn the prop.

barryb-RCU

It's normal. Thick oil for protection while sitting on the shelf = no
compression leak. Thinner oil mixed with gas = leak.

I had a brison 6.4 that tightened up after about 10 hours on the engine. I have a DA 100 with 50 hours on it that has not tightened up. The DA has always made more power.

GeraldRosebery

My Feedback: (14)

Leakage when the engine is cold is irrelevant. The rings seal when the engine warms up for flight. What you feel is absolutely normal. Don't fret - go fly. By the way - the advice to run-in the engine in the air is very good advice. In the air, the engine is always heating up in uplines at full throttle and cooling a lot while coming downhill at idle. Heating and cooling cycles are exactly what you want to help the engine run-in.

Happy flying!

sparkplug

Phew!!!

I feel much better thank you for the information

I thought that I had to run the engine on a test stand before putting it into a plane.

Even during the 24 oz run this engine was idling like a champ and would easilly run in a plane even with only 1/4 throttle available.

I have not set the high speed needle since I did not run the engine past 1/4 throttle yet since it was the first tank.

On the second tank I will set the high speed for a rich setting and then put in the plane for flight. It's going into a H9 80" cap 232 which I cannot wait to fly. My first large plane .

I was very surprised at how much thrust this engine can produce with a 22x8 prop.

Thanks again for your feedback.