oil pump question...

[Jay H]

I'm assuming that the bar oil is run via a very very small pump to oil the bar/chain and that it probably has an intake at the bottom of the reservoir somewhere or a tube... At what point should one worry about running it dry and if this is a problem over time? Would it be a problem to run a chainsaw vertically or even upside down (not that I would try this)?

Jay

 

[elkimmeg]

I have a 1966 Mac 10 10 chain saw still running it oil pimp is still working Some oilers can be adjusted but the most important issue is keeping the oil port passages clean.

I take the bar pff and blow it out witha air gun attached to my compressor about every 10 hours. Place a news paper on the ground fire up the chain saw and observe the oil spray pattern collected by the news paper. That will tell you if it is working properly.

Yes oil pumps can fail and you swa can work is various positions If yo clean then and test themevery so oftem you will know when things are running right

 

[computeruser]

1. Yes, oil is supplied by a mechanical pump in all but a few rare instances. Some older saws used pressurized oil tanks to meter out the oil. The fact that this system is no longer utilized should tell you everything you need to know about it.

2. Properly adjusted, the oil should run out after the gas does. So running it dry should not be an issue if you top off gas and oil at the same time. Even saws with optional high-output oilers like the Australian oiler for the Stihl MS660 seem to run out of fuel before they run out of oil.

3. Oil is sucked up by a tube which is free to flop around in the oil tank. Consequently oil will be drawn up into the oil tube whether the saw is moving, upside down, sideways, etc.

4. The only caveat to (3) is that in the wintertime (the really cold part of winter) the oil may get a bit thick and you should either switch to winter-weight oil or, alternatively, just let the saw warm the tank up a bit before you start cutting. This is one of the advantages of the *pro* saws having magnesium crankcases with integral oil tanks - the oil heats up faster than saws with plastic oil tank/engine cradles into which the engine is inserted.

 

[Gooserider]

As stated earlier, both the gas and oil are sucked up by pickup units located on the end of floppy hoses that will fall to the bottom of the tank whatever position the engine is in. (It was actually a significant technology development problem in the early days to come up with a carb that would let the engine run in all positions...) A properly functioning saw should run out of gas just before the oil runs out, however there is a bit of a caveat on that, or at least there is on my saw... The gas tank has a flange around the fill opening that sticks down into the tank, and one is only supposed to fuel to the bottom of the flange so that there is expansion space in the tank (You want the gas to have room to expand when it heats up from the engine) If I ignore the flange and cram every drop I can into the tank, I find I get about 10-15 minutes more cutting time per tank, but the oil runs out first... Moral of story, don't over fill the tank! :coolsmile: When you run out of gas, you should be able to open the oil tank, look in, and see enough oil remaining to cover the tip of the oil pickup hose.

Any time I have the bar and chain off, I scrape out the groove in the bar, and especially make sure the oil passage in the bar is clean - I find the cut off end of a tie wrap works really well for this, it fits the groove nicely, is strong enough to do a good job without being hard enough to damage anything, and it's free... I make sure there's no visible crud in the saw body hole leading into the bar's oil passage, and try not to get any crud into the oil tank - otherwise I mostly don't worry about it all that much...

My quick and dirty "field test" for whether or not the oil pump is working is to find a fairly smooth light colored surface (like a tree trunk), point the tip of the saw at it maybe an inch or so a way and rev the engine once or twice quickly - You should see a few "skid marks" from the oil getting slung off the chain as it goes around the tip... Takes almost no time as I generally do this as part of my drill in setting up for the next cut - pick my spot by pointing the bar at it, "burp the engine" to verify the oiler, move the bar into position and start cutting... Took longer to type than to do!

Gooserider