Echo CS281-WES melted exhaust cover.

[Markymark82]

Hi all I've been in the industry since 2001 and have recently moved away from Stihl over to Echo. I bought amongst a few other saws /hedge cutter etc from an Echo dealer close to me. I've used older Echo saws before and although heavier than some other brands they were exceptionally well made. I bought a cs281-Wes middle of last year it had to go in with a run issue although I only use Aspen 2! They had it for nearly 2 weeks as Echo had sent out a broken carb and another wasn't in the country under the Echo name although it's a generic Walbro carb I believe (not Zama). When I got it back the job on the day was site clearance of various shrubs and small trees no larger than 6 inches in diameter. This was December 2018 a cold, crisp day. It got to about 2 ish the saw had just been refuelled and had been running again for about 10 minutes snedding, felling the small trees etc, all of a sudden I could smell plastic, looking around couldn't see anything wrong looked at my chainsaw trousers (we've all been there!) nothing. So carried on still could smell plastic looked around still couldn't see any issue, then saw a whisp of smoke come off the saw. Turned it off flipped it upside down to reveal the exhaust cover had melted onto the silencer!

 

Please see photos. 

 

I phoned Ariens who are the distributor of Echo in the UK. They asked various questions then asked me to get it to my echo dealer so it could be looked at. 

 

Today I found out they had put it down to user error. Apparently due to the scuff marks on the side and bottom of the cases they are saying the saw has been left too long idling on the ground and this has caused it to melt! There is nothing in the manual I can see to say you can't do this although knowing that idling a saw for too long stops oil getting into the main crank bearings as there isn't enough pressure at idle to push the oil into them so I don't do this for any real period of time. The other thing is I have a roller shutter lock box and on country roads things move around so scratched are inevitable. 

 

The plastic they they use as the silencer  cover is a nylon, fibreglass mix code PA6-GF. Looking at the temperature tolerances of this material it's rated for a short period of time upto 222 degrees Celsius and a long period at 100 degrees Celsius. This in my mind is far too low for an exhaust area.

 

Im asking if anyone else has had the same problem as apparently I'm the only person to every have had this issue. As I'm looking at all my options.

 

[billpierce]

Think it's quite common on these side exit exhausts on echos. I have seen a few like this. Shame. Dont think it will effect the use of the saw too much. Think folk have cut the plastic back around them in the past. Sorry to hear echo haven't been helpful

[Spruce Pirate]

I had exactly the same problem.  Hot day, put the saw down, think it got knocked over onto the side so it was resting on the plastic, seemed to be enough to get the plastic to contact the exhaust and melted.  I'd had the saw a fair while, just assumed it was an unfortunate incident.  Plastic cover is now off, saw runs fine - just got to be careful to not touch the hot exhaust against anything. 

 

Should probably get a replacement cover really.

[peatff]

3 hours ago, Markymark82 said:

idling a saw for too long stops oil getting into the main crank bearings as there isn't enough pressure at idle to push the oil into them s

What does this mean? The oil is in the fuel not under pressure. 

[Markymark82]

A two cycle engine compresses the fuel in the crack before it's ported into the combustion chamber. That's how it gets in there is a combination of pressure in the crank case and the suction from the piston. This is all created by the pistons movement up and down.

The bearings in the crank case that hold the crankshaft in position and allow free movement using either needle rollers or ball bearings to do so need to be lubricanted this is done using the oil in the two stroke fuel. The oil needs to be forced into the bearing by pressure this is done when the saw is revving. Have you ever wondered why if you leave a saw idling then go back to it, it smokes like hell? Unburnt oil (and some fuel) thats not libricated the intended areas i.e. The bearings in the crank, piston rings etc. 

[peatff]

The bearings only need a minimal amount of decent quality oil that's why the mix ratio in the fuel is so low nowadays. I'd just cut the frazzled bits off the cover and carry on using it till I got a replacement.

[wyk]

On 15/01/2019 at 00:14, Markymark82 said:

A two cycle engine compresses the fuel in the crack before it's ported into the combustion chamber. That's how it gets in there is a combination of pressure in the crank case and the suction from the piston. This is all created by the pistons movement up and down.

The bearings in the crank case that hold the crankshaft in position and allow free movement using either needle rollers or ball bearings to do so need to be lubricanted this is done using the oil in the two stroke fuel. The oil needs to be forced into the bearing by pressure this is done when the saw is revving. Have you ever wondered why if you leave a saw idling then go back to it, it smokes like hell? Unburnt oil (and some fuel) thats not libricated the intended areas i.e. The bearings in the crank, piston rings etc. 

First - that's a terrible design(and I own a similar Echo as well). The exhaust should be directed more outwards(which I did by virtue of opening the bottom of that vent cover and the muffler underneath), and the cage should have a larger relief in case of roll over(you listening, Echo?). Otherwise, we love ours. I was told, back when I had a future in university, that if you must explain to an operator how to coddle your product designed for the field, you have created a terrible design.

 

As for the bearings - at idle, the saw has disengaged the PTO/clutch, and there is much less load on those bearings, and there's much less friction/heat than at throttle. It's the piston that gives up the ghost rapidly without oil. The puff of smoke is likely more due to incomplete combustion on the front of the timing advance and the high speed jet kicking in than lack of enough lubrication.

 

Edited January 17, 2019 by wyk
'spreed' is not a word

[spudulike]

Lubricated!