Anyone familiar with Stihl 075/076 saws?

[Steck]

Just wondering if anyone with some knowledge of the 075 and 076 saws can point me in the right direction regarding the oil pump. Mine was bad (shaft splines were wasted completely). This caused the spring to get bound and the inside surface of the main case to get scored (where the shaft is inside of). I got a brand new NOS Stihl shaft and worm gear. Since I needed the spring, the case was scored and I damaged it further getting the old shaft out, I got an entire used unit. Turns out I have a new style oil pump that I believe was in the newer 075 and 076 saws was sent the old style that was in the earlier 075’s. The newer style has an extended shoulder that seems to mate with a bore deeper inside the case. The older one seems to go in but does not engage that deeper bore. Here’s my questions: can I use the older style one since it’s in perfect condition or do I need to search for the later style one with the extended shoulder? Are they interchangeable and it does not matter what style I run? The IPL exploded view I have shows the newer style that was originally in my saw but makes reference to the other style for saws of an earlier serial number. This seems to matter only for the purchase of a new rubber ring, as the ring is different depending on what style you have. I inserted the old style and it seems to engage and the shaft seems to spin. I do think the later style with the extended shoulder seems to be more solid inside due to the shoulder engaging the inner bore. I’m guessing this was just a design improvement for this reason. Some photos above for reference

 

[jacob j.]

@PogoInTheWoods

 

[Pony]

I've just done the exact same thing.
Swapped a short shoulder pump in a long shoulder housing.
Only fired it up briefly after full tear down a reassembly.
Didn't seem to pump oil but had other running issues so didn't try to troubleshoot.
Following day was knocked off a horse by a irate bull and am a bit banged up so haven't been back since.
Will be interested in other replies.
Pony

 

[Steck]

Holy crap man! Good luck with all that. Rest easy and maybe we’ll get this figured out. I have the short (older) style installed now with the clutch off. Seems to turn nicely when I spin the worm by hand. One thing I did notice that is really important, is that the unit that I purchased (the older one) had a much finer shaft spline pitch than my original. I bought a brand new NOS shaft which had the same splines as the one in the original unit, so I swapped that out. I noticed that difference myself and in speaking with @PogoInTheWoods, he pointed that out too. If the pitch doesn’t match your worm gear it’s a problem. So not only are there two different designs there are apparently two different shaft spline pitches as well. I’m itching to just throw the clutch back on and pull the string, but I’d rather know for sure before I grenade the oiler assembly or worse.

 

[PogoInTheWoods]

I have the original tech note for the oiler changes along with the early IPL's and will post the details if I have time later this evening.

 

[Steck]

That would be much appreciated, but take your time. I don’t need this thing up and running immediately nor do I have a lack of other things going on.

 

[PogoInTheWoods]

I just finished reviewing the service bulletin and there's a bit more there than I remembered. The best way to convey the information will probably be to create a specific PDF if I can't just do it with .jpg attachments. The oil pump stuff is only a small part of a larger volume of updates and will need to be extracted. And after reading the stuff and refreshing my memory, I would indeed resist the urge to put the clutch on the saw and firing it up until you've had a chance to look over the considerations provided in the documentation.

 

[Steck]

Ok will do. Thanks for all the help

 

[Lightning Performance]

@Steck

I just finished reviewing the service bulletin and there's a bit more there than I remembered. The best way to convey the information will probably be to create a specific PDF if I can't just do it with .jpg attachments. The oil pump stuff is only a small part of a larger volume of updates and will need to be extracted. And after reading the stuff and refreshing my memory, I would indeed resist the urge to put the clutch on the saw and firing it up until you've had a chance to look over the considerations provided in the documentation.

That was like two or three pages of Jpegs when it was figured out before. I remember going through it several times messing with a chewed up 075/6 with several mismatched oil pump parts. It was supposedly fixed before. Ended up going with 076 NE pump with 075 drive parts. It had about six variations you can run off a drum or spur with a pin or coupler

 

[PogoInTheWoods]

It had about six variations you can run off a drum or spur with a pin or coupler...

Yep. That was my introduction to these oilers and first major contribution to the cause. I did a fairly thorough write-up about all the drive variations in the '050, 051, 075, 076' thread over on AS since no one seemed to have covered it anywhere else. https://www.arboristsite.com/community/threads/050-051-075-076-info-thread.169996/ This brings up the point that changing a worm to accommodate a new pump shaft pitch also needs to take the clutch drive type into consideration, though I believe the 075 always used the lug drive setup over the more confusing pin drive arrangement..., not to say someone couldn't have rigged one up in a pinch from 050/051 parts somewhere along the line.

Here's what I came up with on the oiler update along with their recommended procedure for fitting a new shaft, etc. Major overkill on the reaming and de-burring, but it's included anyway. Seems like the main consideration is the spring and the ring if swapping out the shaft..., along with using the correct worm, of course. Of note is that there was at least one more change in '84 that I only have reference to with no actual detail. Researching part numbers may or may not determine what it was, but could also become an exercise in futility pretty fast considering Stihl's number changes in general.

In a nutshell, I'd say the parts swap should work given clean bores and the considerations mentioned. It's always fun going back through all this old stuff. Like gold when you need it and not found in any of the newer digital media.

​

 

[PogoInTheWoods]

Last two... Hope this helps a little. Be interested to know how it all works out.

​

 

[Steck]

Wow I’m printing this stuff! How did you come across this info? It supports what I was basically thinking, in that what was in my saw originally was just an improved version. So I think I’ll run it how i have it set up now, since I have the worm, shaft, spring, washers, main body, that all work together. In order for me to run my original setup I will be searching for a new main body and the shorter spring since mine were trashed. I’ll run what I have for now and eventually collect the parts needed to run my original supposedly better unit. Thank you all for the info and ideas. I will update when I run it, hopefully to find Texas amounts of oil blowing out the side of the case!!! Fingers crossed.

 

[Steck]

Well I put it back together last night and fired it today. This thing pumps oil like crazy!!! So there you have it boys, pick whatever style you got, it will work. Having the correct style clutch drive, worm gear, and shaft splines are the key. In other words, the ones that work together as a system with the sprocket/clutch drum and drive washer matching the style drive of the worm gear and the correct pitch between the worm threads and the shaft splines. Now to get cutting the piles of big stuff, winters coming and the OWB is hungry.

 

[Steck]

Pony, just a special note for you. It took the pump about 30 seconds or more to prime and Start pumping. So if you only ran a few seconds and cut it due to your running issue, then you didn’t really give it a chance to pump yet. If you check out that link above for the arborist site, there’s 72 pages of info on these saws. Good luck. And a HUGE thanks to all of you especially Pogo!!!!

 

[PogoInTheWoods]

Glad it worked out for you and happy to help. That's what all those old manuals and IPL's are for. Thanks go to Definitive Dave for loaning me all the hard copy material to digitize a few years back.

 

[Steck]

I also picked this up locally last week. Granberg MKIV Alaskan mill, used once. Can’t wait to make something other than firewood out of the black walnut and oak logs I have around.

 

[Steck]

And one more thing (for now)... the gas cap vent leaks pretty good when I have it on its side (as if for stumping/milling, etc). Anything I can do with it or look for a new cap? It has a brass screw in the side of the cap. Don’t know if that is an adjustment for the vent?

 

[qurotro]

I also picked this up locally last week. Granberg MKIV Alaskan mill, used once. Can’t wait to make something other than firewood out of the black walnut and oak logs I have around.View attachment 259045

It's rare to see one in such condition. .

 

[Steck]

I got really lucky. He had like 20 people interested within an hour of posting it. Drove straight to bank and then to him.

 

[jacob j.]

And one more thing (for now)... the gas cap vent leaks pretty good when I have it on its side (as if for stumping/milling, etc). Anything I can do with it or look for a new cap? It has a brass screw in the side of the cap. Don’t know if that is an adjustment for the vent?

You might just need to replace the red rubber "umbrella valve" in the cap - 1110 353 1600 (Number 20 in the diagram).