Richard Stated Elsewhere:
Thanks for your valuable advice... I think that you are right about the hydraulic problem. See history of problem below. If it was a hydraulic lock I probably started and ran the engine with the lock. ... what is the next step? ... How do i know if I have damaged the engine? Is there some kind of inspection required?
The Back Story:
After restoring fuel flow I flew the plane back to Trenton. Several days later as I pulled the prop through I noticed it was somewhat difficult to move and there was some overflow from the oil tank. There was fuel that had somehow entered the oil tank.I drained that oil and replaced it with sport +4. I did not replace the filter The prop then turned with normal resistance... The engine started and ran normally. After several more days the prop was again very hard to turn. Oil was present in the tank so I started the engine and it ran normally. I then changed the oil and filter. There was no metal on either magnetic plug or the filter.
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You have a Carburetor problem.
Fuel is leaking into a cylinder that just happens to randomly stop with an Open Intake valve. Sometimes it does, Sometimes Not!
Fix the carburetor! Check the Floats and the Float valve. Turn OFF the Fuel Valve between flights.
The hard turning is because with fuel partially filling the cylinder; your normal 10:1 compression may become 20:1 or more. Gorilla strength.
If you have been judicious at pulling the prop through by hand on the first flight of the day it is unlikely you have done any damage.
A cylinder Compression check might make you feel better.
If the engine starts and runs fine, it is probably OK!
The good news also is that the Rotax Starter doe not have the excess power needed to damage the Connecting rods if you were to have a Full-On Hydraulic lock.
A Full Hydraulic Lock would be if you engaged the starter and the engine refused to turn at all. No Cranking, NO Start. No Pulling the prop through by hand. Locked Solid! . . . You have never mentioned this!
