Ethi-no!
Trust in me
If you’ve followed me on socials for any length of time you’ll know I’ve travelled internationally for carving. This is only possible because of the kindness and generosity of my hosts It is actually possible to get a chainsaw on a plane but they don’t much like the petrol. It is far easier to beg, borrow and on occasion, buy tools when you get to your chosen destination. The fear is always that you don’t know what you’re getting. It could be a different brand to your usual set-up or they could be quite old and tired or even new but not very well looked after. Fortunately for me I have over 25 years experience with chainsaws and I’m quite good at maintenance and fault finding. I was also taught to be respectful of other people’s belongings. I have been very lucky to have been entrusted with tools without prejudice with little more than a formal introduction. It does make me think that I must give off a good vibe at least.
Well in response, I have tried to return the favour to some of the internationals who come to the UK. This has mostly worked out ok, until last year when I lent one particular carver a trio of saws. Unfortunately the biggest of the three was returned to me after only a few hours use. Straight away I gave them my big saw to use as not to impede their progress. By lunch time the next day I knew the fate of that saw had also been sealed.
It stated to raise questions like was there an underlying fault? Is it the fuel? Are all of my saws at risk? Is it the operator? Have I not done something that I should have? When you start asking the hive mind, you get a standard set of answers which generally revolve round the fuel. There’s been some changes with petrol over the last few years and I’ve always felt it’s a bit confusing and misleading.
Dilution for economy
The government decided that petrol should have an additive called ethanol increased from 5% to 10%. Information on it is a bit sketchy and most of it references cars which have a 4 stroke engine with a sump and separate engine oil for cooling and lubrication. Chainsaws are 2 stroke engines and have oil mixed into the fuel. There are some benefits to it in that it’s a less harmful chemical in the first place and it produces less toxins as a result of being burnt. It also helps to reduce something called engine knock which is to do with the exact point that the fuel is ignited within the engine. Down sides are that it absorbs moisture in the atmosphere which damages the petrol and causes problems with ignition and it can actually reduce fuel efficiency. Research suggests the E10 fuel starts to deteriorate after about 4 weeks. General guidance is not to have more fuel than you need in the short term and that it should be kept in an air tight container. To me, that means the risk of water ingress is minimalized and leaves a weak argument in the first place. However the petrol may still degrade. I actually left a small container of petrol out uncovered in my workshop and found that it evaporated quiet quickly, even in Scottish winter. I found no trace of water in it. In some countries the ethanol content is considerably higher and of much greater concern. I’ve even seen YouTube videos of classic motorbike owners deliberately mixing water into their petrol. The ethanol sticks to it and then the water separates from the petrol which is then siphoned off, leaving ethanol free fuel.
You can actually buy ethanol free fuel. It’s really expensive though, only available from particular retailers, it comes in plastic bottles and has a particular sweat smell that makes me feel sick and nauseous. It can also affect the running of the engine and might require some adjustment. You can’t chop and change between ethanol free and regular petrol either as doing so can damage the rubber components like fuel lines and the diaphragm pump. It does come pre mixed with lubricant though and it has a long shelf life so its not all bad.
There was for a while some question about quality of supermarket fuel. I’ve only ever had fuel problems twice and in both occasions the fuel was from a BP garage. I only noticed it causing problems with my much more sensitive generator. I use high quality 2 stroke oil designed for chainsaws. I measure it quite accurately and I only buy 20ltrs of petrol at a time which can last between 2 days and 4 weeks. All this considered I don’t feel the ethanol is a problem.
Octane is the other additive which gets some blame. As well as being a chemical, it’s also a measurement of resistance. For example, if you drive a Ferrari which has a very high performance engine, it is more important that the petrol ignites exactly when it’s supposed to and not prematurely as a result of higher temperatures, a bit like what ethanol does. There may be an argument that with the availability of modern fuel injected saws (of which both my damaged saws were) octane may be a factor. I can’t find any accurate data on it though.
Technology rules
So that doesn’t progress the cause any. The great thing about Stihls ms500i saw is that as well as being fuel injected, it’s also fully computerised and a dealer can plug it into a computer and see exactly what the saw was doing. To me this should be available to the user either via a laptop or an app on your phone. It would be very useful information to have and monitor. Of course, obtaining this information from your dealer is very difficult and you’re relaying on them having adequate service knowledge to be able to interpret the information and make a diagnosis.
A blocked air filter might get shamed too. In reality if the saw can’t suck enough air in, it’s more likely to run at slower speed and there for not over heat. A blunt chain could be a factor though. If the chain is not able to cut properly then there’s unlikely to be enough loading on the engine. High revs for an extended period could cause over heating which then is a spiral into disaster. The same can also be said for using a big engine but only cutting little bits of wood.
After coughing up a four figure sum for a replacement saw so that I could continue to operate and a considerable 3 figure sum to have the newer of the two damaged saws repaired. I collected the now running saw along with the removed pot and piston. I was lucky enough to have been given a workshop manual for diagnosing the signs and symptoms of damage within a chainsaw engine. Whilst it predates the ms500i model, it was useful for adding to the picture.
Back to the drawing board
I’d like to say that was the end of it but after only a few hours use I detected some signs that trouble was ahead. Although the engine was still running I could tell it was about to fail and removing the exhaust, I peered into the pot and identified scoring on the piston, again. New engines should not do this. I have a run in sequence which I believe helps align the new components and helps to heat treat the metal. I know the chain was sharp and that it hadn’t been run at high reves. Now concerns were really setting in. There had to be a common problem somewhere right? Back to the shop it went for a warranty repair. This time when I asked what had gone wrong, I was told the main bearing had failed which throws the piston out of alignment and ends up scoring the pot. No one would give me a definitive answer on what causes main bearing failure, but there’s a lengthy list of possible causes.
As it stands I still don’t know how one person can cause so much damage in such a short space of time but at this point I don’t have any more broken saws either. Could it have been competition related sabotage? We will never know!