Modifying a 361 oiler....

[Haywire Haywood]

My 361's bar has been running hot lately and I'm using about 1/4-1/3 tank of oil to a tank of mix. I know the 361's meager oiler is almost legendary around here. I just did a search and re-read all the old posts hoping to find a cure or mod. Unfortunately, none exist in the archives that I saw.

I had my 361's oiler apart this past weekend hoping to find something amiss that I could fix but all looks good. Nothing stripped or plugged. While I had the control bolt out of the oiler, I looked at how it adjusted the flow. It appears that there is an off center nub on the end that controls the stroke of the oiler piston and therefore controls the volume of oil that it pushes. If one were to file that nub back some to lengthen the stoke, it should in theory oil better. The only stress it has is the pressure of the return spring on the oiler piston, so it shouldn't require a lot of strength to do it's job. A machinist could actually mill a new one with a more offset nub if that were a concern.

what do you think? Am I missing something in how the oiler functions? Think my idea will work?

Ian

 

[2000ssm6]

Sounds like a good idea. What about getting 1 or 2 of those "nubs" to play with from your dealer(if they are not expensive). You could file one down or build it up with a torch and braze to test your ideas. Then of they don't work your saw is not down...

 

[pgg]

Yep you can file down the adjusting screws' 'nub' for longer stroke therefore more oil flow, I've done it before, not on my 036 though, adjusted to maximum flow I'll get tank for tank oil/petrol stock standard, seems the 361's are new and 'improved' huh?

 

[Haywire Haywood]

Well, I ordered a new control bolt yesterday but couldn't wait. I modified the one in my saw this evening. I whacked half of the nub's diameter off. It appears to be oiling better, but I won't really know if it made a difference till I get out and cut some. I'll report back in a couple days.

The only reservation I have is in the drawing. Before, the nub controlled the piston by riding on the raised section at the middle of the piston. Now the edge of the piston is riding on the base of the control bolt instead of the nub.

Ian

 

[Lakeside53]

I don't have a 361 pump piston in front of me, but if it's like most other stihl pump pistons, the shoulder is eccentic. Stihl modifies both the shoulder and the control bolt when making volume changes. I published an 066 oil pump upgrade thread a while back. There were some closeups of the bolt and piston differences.

http://www.arboristsite.com/showthread.php?t=31560

 

[pgg]

Believe it or not, there's zero wear and tear on those surfaces, its sprung in there, just get the shape right, it'll run for years, not even hardened steel, I used a simple ground down bolt on one saw for years, shouldn't need to modify oilers anyway, modern saws seemingly getting restrictive on oil output?

 

[Lakeside53]

Not so sure about that.. It does rotate fast, steel on steel... Only a small amount of lube comming from bar oil leaking past the piston.

 

[pgg]

Never seen a worn oil pump yet

 

[Haywire Haywood]

Lake, you're right. I got to thinking about that this morning. My concern isn't an issue. It rides there anyway as a part of normal operation. The purpose of the nub was to keep it from running the entire eccentric part of the piston. It created a "false bottom" of sorts to limit the stroke. By simply removing the nub entirely, the pump will run at max capacity. I cut mine back by about half, which essentially accomplished the same thing. I feel better about it now.

So, to max out pump volume, whack that nub off entirely. We'll see how it goes when I go cut some.

And to the lube issue, there was some grease in there when I took it apart. I regreased it with lithium wheel bearing grease when I put it back together.

Ian

 

[Lakeside53]

Never seen a worn oil pump yet

Well, you'll just have to trust me then - they do... and they get replaced more then repaired because by the time the wear is apparent (they start to bind, and the worms get stripped), the pump case is usually too far gone to just replace the piston.

Used engine oil (my pet ?????) is a great way to wear your pump out fast - and really piss of the repair tech (me).

 

[pgg]

Lake, I'm sure you've worked on many saws in your time, but in my own experience of 30 years swingin' on chainsaws, oil pumps never 'bind' thru normal wear and tear, they'll simply run looser. It's an OIL pump remember Now, the only 'wear' I've ever seen inside an oil pump is a polishing of the surfaces. If an oil pump is 'starting' to bind, the worm'll strip in a nanosecond! The only way an oil pump will 'bind' is if there's a great chunk of grit or sand jammed in there. But hey, Lake, you're obviously an experienced chainsaw mechanic though, if you say you've seen 'seized' oil pumps from normal wear - then I'll believe ya!!

 

[Haywire Haywood]

Report

I cut a load of wood this afternoon and it used about 1/2 tank of oil to a tank of mix. The mod does work . As usual, your actual mileage may vary.

Ian

 

[Cut4fun]

HH, that is just unreal yours dont put out more oil then that. Mine seems to use 50%-60% per tank of mix right now. I wish it used closer to 1 - 1 like my other saws.

 

[Lakeside53]

Mine too... unmodded...

 

[Cut4fun]

The only time I seen lack of oiling to b+c, was when I threw the 32" skip on and cut up some softwood spruce for fun. Just wanted to see if the stocker could do it in a pinch.

 

[Haywire Haywood]

I wish it used closer to 1 - 1 like my other saws.

Tell me about it, but 1/2 is better than the 1/4 to 1/3 it had been using. The bar was still so hot after bucking up that 15" hickory this afternoon that I couldn't change chains without gloves.

Ian

 

[SawTroll]

HH, that is just unreal yours dont put out more oil then that. Mine seems to use 50%-60% per tank of mix right now. I wish it used closer to 1 - 1 like my other saws.

Mine too... unmodded...

I'd say more like 40-50% on my German made one, but I never really measured it.....

...anyway, it oils adequately with the bars I use....:greenchainsaw:

Edit; Forgot to say, that is with veg-oil.....

 

[Gologit]

Mine too... unmodded...

Same here. Would there be enough difference in bar oil types to account for the differences? And NO I'm not wanting to start another damn bar oil thread. Please.

 

[Haywire Haywood]

Stihl and Husky oil.

Ian

 

[Gologit]

Stihl and Husky oil.

Ian

:hmm3grin2orange: Quit it!! Good post about the oiler by the way. Good piece of engineering, too. Maybe Lake or some other good Stihl tech can tell us why theres so much difference in 361 oiling. A friend of mine has one and he has the same problem you do. I showed him your post and he's gonna try it.