Problem with my MS 661

[keptenjim]

I recently needed to use my MS661, so I filled it with Aspen 2 and chain oil and tensioned the chain. I started it and almost immediately noticed that the chain was loose. I re-tensioned the chain and then restarted the chain saw. Again it loosened and then came right off the bar. I switched it off immediately and removed the chain cover and saw that the ‘E’ clip that retains the chain sprocket was missing. I also noticed that the bar was damaged when the chain came off. I replaced the bar and the chain with new ones, fitted a new ‘E’ clip and started it again. It’s now running well but after use where it’s been sitting on the ground, leaves pools of chain oil below it. It seems to be leaking this oil only during and after running and not when sitting unused. Can anyone advise what might be the problem?

[Stubby]

3 hours ago, keptenjim said:

I recently needed to use my MS661, so I filled it with Aspen 2 and chain oil and tensioned the chain. I started it and almost immediately noticed that the chain was loose. I re-tensioned the chain and then restarted the chain saw. Again it loosened and then came right off the bar. I switched it off immediately and removed the chain cover and saw that the ‘E’ clip that retains the chain sprocket was missing. I also noticed that the bar was damaged when the chain came off. I replaced the bar and the chain with new ones, fitted a new ‘E’ clip and started it again. It’s now running well but after use where it’s been sitting on the ground, leaves pools of chain oil below it. It seems to be leaking this oil only during and after running and not when sitting unused. Can anyone advise what might be the problem?

When  the chain de-railed did whack the crankcase part thart forms the oil tank and crack it ? 

[keptenjim]

Don't think so Stubby - looks damage-free as far as I can see 

[Macpherson]

7 hours ago, keptenjim said:

I recently needed to use my MS661, so I filled it with Aspen 2 and chain oil and tensioned the chain. I started it and almost immediately noticed that the chain was loose. I re-tensioned the chain and then restarted the chain saw. Again it loosened and then came right off the bar. I switched it off immediately and removed the chain cover and saw that the ‘E’ clip that retains the chain sprocket was missing. I also noticed that the bar was damaged when the chain came off. I replaced the bar and the chain with new ones, fitted a new ‘E’ clip and started it again. It’s now running well but after use where it’s been sitting on the ground, leaves pools of chain oil below it. It seems to be leaking this oil only during and after running and not when sitting unused. Can anyone advise what might be the problem?

Hi, I'm not sure how a missing E clip would make the chain lose tension and get so slack as to fall off the bar... but I'm probably missing something🙄

[keptenjim]

I agree with you - I don't know what happened there. The second time I tensioned the chain, I paid close attention to what I was doing. In retrospect I should have looked under the chain cover after the first mis-start. But that's another story - right now I'm trying to get to get to the bottom of the oil pools 

[spudulike]

From what you are describing, the saw only leaks when running so seeing as the bar should seal the oiling channel, as long as the bar oil hole is clear, the oil will be coming from around the bar mount, or from the oil pump gear shaft up to the oil channel. 

The most logical cause is that the drum coming off caused some damage to the oil channel/pipe between the oiler and the oiling channel.

Remove the drum and clutch, check for damage around the oil pump to bar mount as I can't see any damage on the bar mount.

I am assuming that the bar is clamped tightly by doing up the bar mount nuts.

[spudulike]

One other suggestion, spray WD40 in to the oiling hole to the back of the oiling channel whilst plugging the gap around it. Do this and check for leakage from damage ....it is possible the loose e clip has cracked or damaged something.

There is a small rubber sealing ring joining the pump to the oiling channel feed. If this is missing or is damaged, the oil will do what you have .

 

[keptenjim]

Cheers Spudulike - many thanks for this info. I'll work on it tomorrow and let you know what I come up with. Thanks again 

[keptenjim]

On 26/04/2022 at 17:57, spudulike said:

One other suggestion, spray WD40 in to the oiling hole to the back of the oiling channel whilst plugging the gap around it. Do this and check for leakage from damage ....it is possible the loose e clip has cracked or damaged something.

There is a small rubber sealing ring joining the pump to the oiling channel feed. If this is missing or is damaged, the oil will do what you have .

 

I did what you suggested re the WD40 trick although I don't know how successfully I covered the gaps! But I didn't see any leaking fluid. I cleaned it out and gave it a close inspection with my untrained eye but didn't see any damage. I then reassembled it and ran it and ended up with oil pouring out as before. So I quickly disassembled it again and tried to see where the oil was coming from and I get the impression that it's running down mainly from the oil delivery channel. I am now wondering if the metering system whereby the rate of oil delivery to the chain can be adjusted, is perhaps damaged, and the pump is now delivering too much oil up to the chain?

[Mark_Skyland]

It's possible that tut metal arm on the worm wheel is damaged. This locates into the drum so that the oil pump only pumps when the drum spins. If it is spinning at engine speed all the time then it will be constantly pumping oil. They usually wear and don't pump enough oil but it's worth looking at.