How often do we give our fire service saws a soup to nuts inspection and cleaning? Iâ€™m sure that there are people reading this with a wide range of answers; once a week or after every use that saw gets completely disassembled, inspected and cleaned, some might say we send it out to a shop for tune ups and inspections, and some might say they donâ€™t because they never have been taught or trained to do anything but run them.
After taking a truck academy class on the west coast that spent time teaching students the basics on how to properly break down, inspect, and clean chainsaws, I felt the need to share this information with the members of my department and spread the knowledge when teaching around the country. To my knowledge, very few people really incorporate this topic in their saw 101 curriculum. Itâ€™s something so basic but the student feedback I get states it is much wanted/needed and the students really enjoyed getting their hands dirty.
Learning this information sparked a big interest for me. I ended up working part time at a repair shop to further the little bit of knowledge I had. In doing so, I was able to repair the small engine power equipment in house and reduce downtime and costs. Below are a few things Iâ€™ve discovered along the way.
The number one cause for people dropping off their small engines for repairs is gummed up carburetors from using bad fuel. Most local gas stations have blended ethanol gasoline. Ethanol causes damage to fuel systems and engines along with attracting and absorbing water from the air. Ethanol fuel will go bad around 30 days if you donâ€™t use a good additive/stabilizer to help lengthen its life span and absorb water. When the fuel and water mixture occurs it will create a varnish in the carburetor when sitting for a period of time. What will also happen is the fuel and water will separate creating different layers in the fuel tank, causing water to be drawn into the engine, thus causing expensive damage (water is not combustible).
Think about how long the fuel has sat in the gas can or the saw? Unless we are using the saws on a routine basis, we truly donâ€™t burn through that much fuel. The most action some saws see is when they are started up once a week and then bounce around on the bay floor for 5-10 minutes. We place the saws back on the rig to sit, leaving plenty of time for separation to occur.
If the fuel has been in the saw for one- two months, dump it all out and start fresh. Dumping the fuel will allow you to also inspect the fuel filter and fuel pick up line as well. Fuel filters need to be replaced every so often and the fuel lines will also deteriorate leaving pieces of line in the tank. Deteriorated fuel lines are also a common cause for saws not running. How does the fuel make it to the carburetor if there isnâ€™t a pick up line?
Solving the Fuel Problem
Using non-ethanol (straight) gas will help solve this problem. Non-ethanol gas will not separate with the water like ethanol will. There was a time we used to send a member on our department 45 minutes away twice a year to refill 5 gallon gas cans that we would then disperse into the small one gallon cans with the 50:1 oil mixture. This practice proved to be a waste fuel and money due to lack of use. The solution to this problem for us was switching over to the premixed cans like Trufuel and Stihlâ€™s Motomix. The fuel comes premixed so we are always adding a consistently mixed 50:1 high octane ratio. The shelf life is good for 2 years after the seal is broken. We have noticed that the saws have had an increase in performance with the pre-mixed fuel.
An added advantage to the smaller can is that you can slip a premix can into your bunker pants pocket instead of carrying a 1 gallon gas can when youâ€™re climbing a ladder to the roof on a big cut job.
Cleaning and Inspection
How thorough are you on this portion of maintenance? I am definitely guilty of just wiping down and cleaning the visual dirt off the saw, fueling it back up, and then placing it on the rig because thatâ€™s what I was shown. The following photos detail common issues that I have come across.
That metal stalagmite above came from the inside of a shroud. Metal built up after cutting rebar and steal for a long period of time and you can see that there was a grove created, thus wearing the blade down faster. Be sure to peek inside the shroud every so often and clean it out when needed. People run all sorts of wire in the attic and it tends to get caught in the saw blades and wrapped around the pulley.
The saw pictured above was used on the interior of a commercial structure fire. There was a large amount of standing dirty water in the building and the saw ended up being submersed in water. The exterior was wiped off, yet the covers were never removed to service everything else. Debris ended up in the flywheel not allowing it to turn when the pull cord was engaged. The magneto (green in color) was also dirty, not allowing it to generate power for the spark plug, thus the saw could not run. This is also a good time to check the pull cord for tears and frays. It is easier to replace the pull cord in quarters then to have it snap on a call.
Itâ€™s important to pull off covers that allow you to gain access to the cylinder head for inspection and cleaning. Cutting roofs will lead to a buildup of tar and debris on the cylinder head and also the flywheel vanes. Once the engine gets hot the tar will melt to the cooling fins causing the saw to overheat. It was explained to me that tar on the cooling fin is equivalent to blocking the front of the radiator on the fire engine and seeing how far we can make it before the rig overheats from no air flow.
I find using brake cleaner, a hard bristle brush, and an air hose has worked well for cleaning the tar off. A can of brake cleaner goes fast and is not the cheapest solution either, so staying on top of it will help keep those costs down. Be mindful of where you spray that cleaner as well. Try to avoid the rubber and plastic pieces. Donâ€™t forget to keep the carburetor choke closed and stuff a rag into the throat if the air cleaner is removed during the cleaning. That will help prevent the dirt from entering the intake or carburetor. This is also a good time to change the spark plug if needed, clean off any air-inlet or exhaust screens that might be built into the engine covers, and clean or replace the air filter.
On the second photo, the decompression valve, (blue button), can be removed with a box wrench and cleaned. Carbon deposits can build up on this overtime.
Belts and Pulleys
In a car you replace your serpentine belt after so many miles because of cracking on the ribs and the belt stretching over time. The same concept applies to these engines. We sometimes rely on the tension indicator hole that shows the silver washer between the two arrows, indicating the correct amount of tension on the belt. Itâ€™s also important to find the small hole on the bottom of the belt cover and touch the belt with your finger to see that the belt is taught and there is actually tension. There have been times when saws are put back together and the belt cover is not properly lined up. The tension screw is turned showing the washer is in the correct spot but the belt may actually still be loose.
Tension indicator nut
When looking at the belt, remove it and inspect both sides. Look for materials embedded in the grooves. In the next two pictures the belt shows pieces of metal embedded in the grooves and ribs which put small cuts all over the belt. This is fairly common and spare belts should be kept in stock to minimize down time.