Its the small things that will get you..
A couple of years ago I purchased a stihl 036 along with a ms390 as a package deal from a golf course. The 036 had a 18" bar and the 390 had a 20" bar. With a little maintenance and cleanup they were both running.
I installed the 18" bar on the ms390 and put it to work. All good.
I put the 20" bar on the 036 and gave it a test run, no bar oil. I removed the drum and found it to be cracked, ordered and installed updated version with the large rim. I removed clutch to find the plastic worm gear had failed. Cleaned out the debris and installed new aftermarket worm. Installed the 20" bar and went to test cut. Chain oiled fine for about a 1/4 tank and started to get warm/dry. Removed bar and chain, checked tank vent, took a blow gun and blew the rails out. Blew air through the oil holes on bar to clean out. Topped off oil and test ran without bar, pumped oil fine. Installed bar and test cut for about a 1/4 to 1/3 tank and again chain got dry. Set saw to the side, time to read up and study the internet for suggestions.
Months later I found a suggestion about draining the oil, rinsing with gas, and actually letting the saw pump the gas with the bar off to remove any contaminants. I did that and put saw back to work cutting firewood. It seemed fine for a few days and all of a sudden dry. I remembered that when I was surfing the internet for a cure to the problem, aftermarket worm gears were not highly respected. Naturally this will be the problem. Ordered brand spanking new worm gear from the STIHL dealer. Removed clutch and found old gear to appear fine but installed new one. Test cut and again after doing the same practice of blowing the bar rails and oil hole out it seemed good for about a half of tank. Put saw on the way back burner.
A couple weeks ago had to rearrange my corn crib where i stack my wood and saw the 036 from satan. The stubborn german in me kicked in and I decided to give it another try. I disassembled and removed oil pump. In the attempt to remove the suction hose and screen I tore it slightly. I noticed it seemed kind of hard and brittle. Maybe it was not pliable enough to keep sealed against pump. Ordered new suction hose and oil tube kit from hell. With pump removed and turning the gear by hand, it pulsed oil out fine.
That brings us to today. New parts are here, saw is cleaned up, tank is spotless and time to put together. Suction hose and screen into tank-easy. New oil tube to bar-not so much. Attempted to install tube on pump cold, not a chance. Warmed up with hair dryer, got over first barb and stopped. Go find the worst china pliers and drill a .200" hole in the jaws. Reheated tube and pump and with pliers was able to get on the rest of the way. Finished assembling saw and test ran with out the bar. Pumped oil instantly. cleaned off the bar with the blowgun and installed. Started saw and warmed up. I noticed it was oiling nicely. I made a short cut and set saw to side idling while moving some wood around for more cutting. When I went to cut, oil came slinging off the chain like a non pro 026 with a crank driven pump. Happy me, until... several cuts later, not enough oil. WTF?
Just for chits and grins removed bar and inspected and found oil hole to be blocked with saw dust. What do I have to loose, installed 18" bar. Cut wood a few hours with 18" bar and seems to work fine. I'm confused. Is the chain for 20" bar causing a problem? Did I get the rails too tight when doing bar maintenance? Are the oil holes formed differently on this stihl bar than the others? Time to investigate. Wiped off bar with a rag and grabbed a pick that fits between the rails. Doug out the burnt sawdust from not having oil from between the rails. Got to the rear portion on one side and felt a slight bump. I scraped around with an oring pick and cleared the oil passage and sure enough it was partially blocked but not with sawdust. It was hard. It felt like the right angle pick was about to break when it finnaly freed itself from the grove. Its a 1/4" long and .050 wide. It does not stick to a magnet so im guessing its aluminum.
The saw might have worked fine if the bar would have been installed the other way. I was always mindfull to put the more worn side up. This time it cost me.
Thats what I did today!