Stihl oilers,again

I stumbled on to this from Magnus' site .A little blurb concerning an old 08 Stihl .

It seems they once made different pump pistons to increase or decrease oil flow . So I says to myself,self perhaps it's as simple as shortening the pump piston to increase the flow on wimpy Stihl oilers most people as less than thrilled with .

If I get time today I will dissect an old pump from an 042/048 and further investigate this possibility .As far as I know the actual design of a Stihl gear driven pump is pretty much the same on every one of them ever made .The method they are driven by might be different but not the actual method the pump operates on .

You have it backwards, Al. According to the bulletin you just posted, the longer piston pumps more oil.

Skwerl said:

You have it backwards, Al. According to the bulletin you just posted, the longer piston pumps more oil.

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Piston stroke,not neccessarily length .At least that's the way I took it .

Wonder what that service bulletin means by, "Lots of reving and not much cutting"?

I think if you look at the context it's written they were refering to the fact that this small saw was ideal for underbrush cutting because it was small . Not too many well made smaller saws in 1968 the date of this service bulliten .

As such,cutting brush,it wouldn't be subjected to long hard cuts but rather just little short bursts of speed and power .

In '68 I think that was about the time frame of the infamous Mini Macs and tiny little Homelites and before the Poulan s-25's .So really there wasn't much of a quality made small trim saw in those days .

I think I'm on to something

I just might have cracked the mystery .

The pic is a Stihl 048 oil pump which is gear driven just like the 038 from nylon gears .I believe they all work the same though .

At any rate the flow is controlled by a rod which is cut eccentric to it's shaft . By turning this rod the pump piston shoved tighter into it body .This also lessens the amount of recipricating travel to the pump .

Pump itself has been cut on a slant ,barely visable in the picture .As it turns it makes contact with the straight portion of the control shaft and thus goes back and forth . That thing could not move much over 40 thou or so if that much .

Now I have an idea that if the short side of the eccentric could be taken down by grinding say 10 thou or so it would or should increase the oil flow a tad bit . If this would work about any body with a steady hand and a Dremel could do it .

I don't really know myself but I'll delve into it when I have the time and see what happens .

Al, you might try to use the close up function on your camera...I recently "discovered" the setting on mine and it works a treat for shots like that.

And don't be skeered of fingernail clippers!

I think Al works in electrics too, so he needs to strip wires.

Now iffen I clipped my greasey old finger nails how in the world could I pick my nose or scratch my butt I ask you . You have to keep your prioritys now .

That cheapie camera will not take a close up .I have to guess at the range .I've been going to get a close up deal for my HP camera but never got around to it .

So much for greasey finger nails and smelly old men,back to the oiler .

In looking at that gizmo some more it appears you cannot lengthen the stroke too much or it will kind of loose its' suction on the pump end where the little slot in the shaft is .The thing rotates the slot towards the suction side of the pump ,picks up a tad bit oil,pulses back on rotation then recipricates back while turning the slot to the discharge port and dumps the oil outward towards the bar . Clear as mud,eh .

I did grind about 7-8 thou off the low end of the eccentric which should lengthen the stroke about that much .Now I need to install it in the only saw I have running that will take that praticular pump which is an 042 .

About the only way I know to test it would be to install a small piece of tubing in the oil discharge hole and measure the oil out put over say a 5 minute period at idle with no bar installed .Compairing the two pumps that way may or may not show if improvement has been made .

You could compare how much oil is left in the tank after using up a tank of gas, before and after. That would be scienterrific!

That might not be a bad idea .I'll have to wait until I get some more wood to cut as I have mountains of it cut and stacked already ,ran out . Jeez I worked myself right out of a job .

I've got a couple of large trees to come down after the leaves have fallen.I'll get on it then .

The new oilers only pump when the chain is turning. No oiling at idle.

Those environmentalists, what will they think up next!

DTW902 said:

The new oilers only pump when the chain is turning. No oiling at idle.

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So do the older ones .If you take the chain off though where the clutch drum will engage at idle they will oil .Not very much though but some . If not just set the idle up a tad bit .

One way or another we're going to get oil out of a Stihl,by George .