914 crankshaft turning resistance during first 10 degrees

They were using thru bolts by 2016 so fretting shouldn’t be an issue.

Sam is correct, fretting crankcases were on the older engines (2006) and mostly found with the 912ULS (100hp). 

If you go to the Rotax 914 line maintenance manual located here - https://www.rotax-owner.com/pdf/MML_914_Series_ED2_R2_E.pdf

Section 05-50-00 subsection 3.9 (Hard to turn over) page 20 provides a specification. The check must be done with the gearbox installed.

“Torque must be determined with a suitable jig. To do this, determine the maximum occurring torque on the propeller shaft necessary to move the whole crank drive. The torque must be max. 150 Nm (110.64 ft.lb)”

When replacing the crankshaft during overhaul, the crankshaft is rotated to make sure that it rotates freely; however, there is no specification or torque number recorded during this check therefore you must complete this inspection using the above instructions found in the line maintenance manual Section 05-50-00 subsection 3.9 (Hard to turn over) page 20. 

We have seen some (very few) engines have a “tight” spot when rotating, and that was due to a build-up of lead that fell off the piston dome and took up clearance between the piston and cylinder head. We have only seen this on a couple of engines that operated 100LL for hundreds of hours and without frequent oil changes. 

What type of fuel are you using?

Thank you foor the response. I mounted the gearbox  and burb  the engine. Left the engine for 24 hours and today I did the tests as described line maintenance section 05-50-00 section 3.9

I found the following values. Start I measured 37,2 ft/lb. Slowly moving around (360 degree) I found  two tight spots and needed friction torque 41,4 and 75 ft/lb rotate through

Overall the rotation friction torque through was 20 - 12 ft/lb  over the 360 degree rotation.

I checked the tight spots. Stopped just before the resistance and wait 10 to 20 seconds. The more a waited the more torque I needed to pass the point.  I found values 109 and 66 ft/lb. Rotating continued  over the 360 degree there was no real tight spots anymore observable.

I tested the free movement ( 30 degree ) of the Gearbox and made sure  the crankshaft was fixed.  The torque was 84 - 109 ft/lb

Rotation the gearbox it makes sometimes a "dry" rasping sound. ( like it is dry inside on a bearing or ring)

I use fuel Super plus without ethanol  98 octane

include some pictures of the dog gear and dog hub.

From the pictures I thinks it's time that gearbox was sent in and get overhauled.