Author Topic: Sometimes loose chain... (Read 1204 times)

mrcaptainbob · « **on:** April 07, 2013, 11:10:46 PM »

Had an interesting experience with my MS310 today. Put a new bar and new chain on Saturday and did some cutting. It started running 'strange' as if there was no oil to the chain by the end of the day. It was quite tight. Today I put another chain (used) on it and it spun by hand just fine. Tightened it the normal manner. Start the engine and that chain snugged right up! Even the engine rpm's changed! The bar looks fine. All straight, no kinks. I had the engine running at idle and backed the adjusting screw and that engine started picking up rpm's! It runs fine with a slack-at-install chain. So....do you suppose the crank bearing is shot? Would that cause it to tighten up?

ladylake · « **Reply #1 on:** April 08, 2013, 05:10:08 AM »

Make sure the drive spocket bar and chain all mastch up. Either 3/8 or .325. . Steve

Al_Smith · « **Reply #2 on:** April 08, 2013, 08:11:49 PM »

New chain ,old spur or rim sprocket can cause some odd behavior .Old stretched chain ,new drive system usually no problems .

DigDug · « **Reply #3 on:** April 08, 2013, 08:48:55 PM »

Check the clutch drum bearing.

clww · « **Reply #4 on:** April 08, 2013, 09:08:49 PM »

I'd be taking a look at that sprocket.

mrcaptainbob · « **Reply #5 on:** April 08, 2013, 11:29:01 PM »

Yeah, the sprocket does appear worn. I put that one on a few years ago. One of those that the chain rides on rather than the gear type. This looseness is dramatic. I suspect that bearing on the drum, too. Raining the next few days, so I'll have plenty of opportunity to study the problem. Thanks for the help.

joe_indi · « **Reply #6 on:** April 09, 2013, 02:27:10 PM »

Try rocking the clutch drum on the shaft.If it rocks too much, this could be the cause of the problem. When you tension the chain the clutch drum is pulled forward, but is at an angle on the crankshaft. The clutch digs into the drum in the front but runs with a wide gap at the rear.

Joe

mrcaptainbob · « **Reply #7 on:** April 15, 2013, 10:04:43 PM »

I checked that, joe_indi, and you were right. That cup was WAY to wobbabbly! I also noticed I was using less bar oil than normal. I'll be getting a new oil pump spring arm tomorrow along with that bearing. I'd like to know what causes that spring arm to wear out as often as it does. This is the third one. Dunno. Maybe they have a life to them. The saw gets lots of use and is a several year old MS310. Oh well. New parts tomorrow will make for a new saw.

mrcaptainbob · « **Reply #8 on:** April 16, 2013, 10:55:12 PM »

YIKES! What a difference new parts make!!! The new clutch cup, bearing and driver made a world of difference. I especially like the new robust design, too. A thicker, larger bearing, and thicker driver. Impressed. A new oil pump driver, too. I think the old one lost the end because the clutch cup was wallowing around so much that it wore the wire end off.
Thanks so much for the help and guidance.....

clww · « **Reply #9 on:** April 16, 2013, 10:57:23 PM »

That's a great post. I'm happy your saw is back up and running properly.

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