DLE 55 - knocking noise

[3dcarter]

Fellas,

ever since I've even heard the name DLE 55, I've always heard people talking about the "knocking" sound the motor makes close to top-dead-center. When I finally invested in a 30% airplane, a DLE 55 was a part of the package. I've had the plane for almost a year with over 200 flights roughly 10 gallons through the motor, with absolutely no problems. The only time it's ever died mid-flight was due to fuel tubing ripping. For as long as I've had the motor, I've noticed the motor knocks fairly loudly at top-dead-center. I haven't made anything of it because the motor keeps running very strong and reliably. I've talked to a guy I fly with and he told me he's rebuilt many 55's and he said the problem is some bearing somewhere near or around the crankshaft. I just took mine apart and concluded mine was due to some play where the connecting rod joins the crankshaft.

Please post if you have this "issue" if it even is one. If it is, what should I do to fix it? I would like for the motor and plane to keep going strong but don't want to do anything if I need not worry.

 

[njswede]

Please post if you have this "issue" if it even is one. If it is, what should I do to fix it? I would like for the motor and plane to keep going strong but don't want to do anything if I need not worry.

"Knocking" as in "clicking" or "rattling" near dead center when you crank the prop? In that case, it's not an issue and is caused, as you noted, by some play in the connecting rod bearings, either by the piston or by the crank shaft. Here's my PTE36 after only a couple of flights (the sound on the video sounds louder than it is in reality):

[video=youtube;aCFE_wPFHPE]https://www.youtube.com/watch?v=aCFE_wPFHPE[/video]

I have a similar noise on my DA50. Everyone I've asked tells me it's normal as the bearings get some wear and is nothing to worry about. Both my PTE36 and my DA50 run just fine!

 

[3dcarter]

"Knocking" as in "clicking" or "rattling" near dead center when you crank the prop? In that case, it's not an issue and is caused, as you noted, by some play in the connecting rod bearings, either by the piston or by the crank shaft. Here's my PTE36 after only a couple of flights (the sound on the video sounds louder than it is in reality):

[video=youtube;aCFE_wPFHPE]https://www.youtube.com/watch?v=aCFE_wPFHPE[/video]

I have a similar noise on my DA50. Everyone I've asked tells me it's normal as the bearings get some wear and is nothing to worry about. Both my PTE36 and my DA50 run just fine!

alright cool. I didn't know if I needed to replace the bearings in there or not.

 

[njswede]

How loose are they? In my case, it was a matter of a small fraction of a millimeter play. Just enough for it to rattle. If it's really loose, replacing it may not be a bad idea!