Echo CS390 - Chain spins when pulling on starter rope

Echo Echo

Echo Echo

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Hi all. The title of this thread pretty much sums up my problem. The saw was running as expected, but something clogged up the oil flow. I broke it down cleaned it up. reassembled it and then noticed that the chain was spinning as I pulled the started rope. I broke it down, and this time pulled the drum and then broke the clutch when I removed it (lesson learned). Just received and assembled new clutch and drum bearing, but the symptom is the same - the chain moves when I pull on the rope. If I start the saw, the chain spins as it would after a cold start, but even after it's warmed up it keeps on spinning. Applying the brake stalls the saw. I can turn the drum/sprocket assembly by hand, but there is resistance. That's the part I'm uncertain about - should there be friction? Any/all advice is much appreciated.
As I typed this it occured to me to pull the cover off my smaller Echo and see if there is friction. I'll do that now, but please feel free to offer advice.
Thanks
 
hotshot

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Should be no friction when spinning the drum by hand.

Sounds like you have installed a washer or needle bearing that’s too wide, or used aftermarket parts. Check your assembly per the IPL, may simply have a washer in the wrong place.
 
Westboastfaller

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Things that will cause that would be a broken clutch spring or weak or wrong springs, bad bearing or kevlar or topo thread around the shaft and bearing. Chain not on sprocket.
Possibly clutch on upside down? Sold you the wrong clutch? Maybe on ovel shape drum is a possibility?
 
Echo Echo

Echo Echo

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Thanks Randy. I did buy echo parts. The drum has 2 notches cut on the opposite sides. They can be seen in this diagram. When I slide the drum over the clutch, I have to rotate it until those notches slip over and lock on to something behind the clutch. Im assuming that's #10 called "14 Collar". I'm guessing that thing should spin freely, but probably isn't. I'll pull the clutch again and see if that'll pop off.
Thanks again. Joe
1601762864869.png
 
hotshot

hotshot

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That’s pretty complex for a drive clutch, and the collar may turn the oil pump too. Try to tighten the nut down in small increments, to see where the bind is occurring. Bearing #4 cannot be pinched at all, it must have a few thousandths axial end play.

OEM clutch parts are best for your Echo.
 
SteveSr

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Thanks Randy. I did buy echo parts. The drum has 2 notches cut on the opposite sides. They can be seen in this diagram. When I slide the drum over the clutch, I have to rotate it until those notches slip over and lock on to something behind the clutch. Im assuming that's #10 called "14 Collar". I'm guessing that thing should spin freely, but probably isn't. I'll pull the clutch again and see if that'll pop off.
Thanks again. Joe
View attachment 859062
#10 looks to be the oil pump drive. Check to make sure that it spins freely and is not melted onto the crank shaft. Make sure that #9 washer is facing the correct direction. On Stihl's they are labeled. #10 must move freely from the crankshaft or the clutch. You should be able to test it with a thin screwdriver after the clutch is installed and BEFORE you put the clutch drum back on. This should confirm where it is hanging up.
 
Echo Echo

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#10 looks to be the oil pump drive. Check to make sure that it spins freely and is not melted onto the crank shaft. Make sure that #9 washer is facing the correct direction. On Stihl's they are labeled. #10 must move freely from the crankshaft or the clutch. You should be able to test it with a thin screwdriver after the clutch is installed and BEFORE you put the clutch drum back on. This should confirm where it is hanging up.
That seems to be the problem. I can get a screwdriver on #10 and it turns, but not freely. I need to put pressure on it. I'll remove the clutch later and see what's involved with pulling #10 off the shaft.
 
Echo Echo

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So I found that #10 sticks to the crank. The propeller is metal but the collar is plastic and it must have melted some for now it’s too snug. Rather than trying to sand it loose again I r gone and ordered a new one. We’ll see but I’m pretty sure that’s the part I need.
I think I need to look at the oil pump as well as lack of oil is when my problem started.
Joe
 
SteveSr

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So I found that #10 sticks to the crank. The propeller is metal but the collar is plastic and it must have melted some for now it’s too snug. Rather than trying to sand it loose again I r gone and ordered a new one. We’ll see but I’m pretty sure that’s the part I need.
I think I need to look at the oil pump as well as lack of oil is when my problem started.
Joe
Check the oil pump gear to verify that it spins freely. If it does not you have a problem with the pump. #11 is the worm gear that drives it. The oil pump worm needs top move freely from the crankshaft once the clutch is installed and tightened down. Once you get this far install the clutch drum (locating the 2 tabs for the worm drive) and bearing and it must also spin freely of the crankshaft.
 
SteveSr

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So I found that #10 sticks to the crank. The propeller is metal but the collar is plastic and it must have melted some for now it’s too snug. Rather than trying to sand it loose again I r gone and ordered a new one. We’ll see but I’m pretty sure that’s the part I need.
I think I need to look at the oil pump as well as lack of oil is when my problem started.
Joe
Melted worm gears are usually caused by excessive heat from the clutch slipping due to operator error running at less than WOT in the cut or by forcing the saw to cut with a dull or incorrectly sharpened chain.
 
Echo Echo

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The worm gear is metal and appears intact. and it spins freely. I can't tell how the pump gear works, so I suppose I'll pull the pump later and check it out.
Thanks for all of your input, Steve. I'll continue to post as I work through this problem.
 

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