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Stihl 045 AV Rebuild.

PogoInTheWoods

PogoInTheWoods

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On the piston issue...

My understanding is that the 'A' designation is generally the smallest of the three with 'C' being the largest -- relatively speaking. An AB piston is generally accepted as having an appropriate fit between an 'A' and a 'B' piston for either an 'A' or 'B' cylinder. Generally, a 'B' piston would be slightly oversized and not desirable for use in an 'A' cylinder, let alone a 'C' piston in either a 'B' or an 'A' cylinder. Conversely, an 'A' piston used in an already larger 'C' cylinder could potentially produce less than desirable performance results due to excessive clearances..., especially in an already worn 'C' cylinder.

Granted, the tolerances involved are small and may or may not affect a given application one way or another in any discernable way. On the other hand, and if tolerances are very tight, performance may indeed become an issue..., if not the fitment itself when a 'B' or 'C' piston is used in correspondingly smaller cylinders.
 
Gaudaost

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Yes, your understanding was in keeping with my findings :) The c piston was indeed marginally bigger, but honestly, this won’t be his firewood saw, it will be on display 98% of the time. The differences were very minor. For a race saws I understand It’s different. For a leisure saw as I understand from Jerry, it won’t be an issue. I’m going to run a tank through it before giving it to him so I’ll put it through it’s paces. In an ideal world I’d have used a C piston, but being so old and hard to source parts, this seemed like a good affordable solution, not to mention the “new” piston came with rings that had a tighter end gap which is good!:) I’ll keep everyone updated!
 
Mad Professor

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More expensive and less reliable than sticking with a points setup. I've been fortunate enough to have run across a complete crankcase with the points crank and supposedly good bearings on both sides. We shall see. If the cranks in those 045's have the cam lobe for a points ignition, they're definitely worth hanging onto along with the flywheels and any other points ignition components that may have come with those cases.

Coincidentally, I also happen to be doing a complete rebuild on an 048. The oil pump assembly itself from the 045 is a direct bolt on replacement for the 048 and several other saws of the era. There are different sizes of gears for different saws, but the pump is interchangeable.


Not to derail the thread, but what are you using to cross reference part numbers between various saws that used the parts?

I didn't know 056 shared an oil pump with 038. I have a 056M that needs a pump, and have LOTS of 038 part saws/carcasses......
 
Mad Professor

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On the piston issue...

My understanding is that the 'A' designation is generally the smallest of the three with 'C' being the largest -- relatively speaking. An AB piston is generally accepted as having an appropriate fit between an 'A' and a 'B' piston for either an 'A' or 'B' cylinder. Generally, a 'B' piston would be slightly oversized and not desirable for use in an 'A' cylinder, let alone a 'C' piston in either a 'B' or an 'A' cylinder. Conversely, an 'A' piston used in an already larger 'C' cylinder could potentially produce less than desirable performance results due to excessive clearances..., especially in an already worn 'C' cylinder.

Granted, the tolerances involved are small and may or may not affect a given application one way or another in any discernable way. On the other hand, and if tolerances are very tight, performance may indeed become an issue..., if not the fitment itself when a 'B' or 'C' piston is used in correspondingly smaller cylinders.
I'm happy to see a thread where someone is bothering to check these clearances! I learned about the A B C sizing when I did my first 038 many years ago.

From Tom's measurements it looks like 0.10-0.13 mm/ ~ 0.004-0.005" clearance. A little loose but not terrible for a 40+ year old saw. Not sure what tools were used to measure things?

Like usual from Tom, great pictures, and some spotless top notch work, with attention to details, on a rebuild!!!
You can totally dismantle the bearings to clean them up, polish the races and inspect each ball for pitting. Most won`t attempt it but it is possible.
I'd like to learn how this is done. I guess if you can get the balls out you could put new replacement balls in (possibly higher quality), if the races were in good shape. Agreed if you can get a replacement not worth the effort. I've got a LOT of old equipment so the skill would be something useful for me. PM me if you have the time to explain this.

I've restored a lot of vintage bicycles from the 60s-70s with Campagnolo parts, but those bearings readily separate from the races. I've got boxes of record/super record parts........
 
Gaudaost

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I'm happy to see a thread where someone is bothering to check these clearances! I learned about the A B C sizing when I did my first 038 many years ago.

From Tom's measurements it looks like 0.10-0.13 mm/ ~ 0.004-0.005" clearance. A little loose but not terrible for a 40+ year old saw. Not sure what tools were used to measure things?

Like usual from Tom, great pictures, and some spotless top notch work, with attention to details, on a rebuild!!!

I'd like to learn how this is done. I guess if you can get the balls out you could put new replacement balls in (possibly higher quality), if the races were in good shape. Agreed if you can get a replacement not worth the effort. I've got a LOT of old equipment so the skill would be something useful for me. PM me if you have the time to explain this.

I've restored a lot of vintage bicycles from the 60s-70s with Campagnolo parts, but those bearings readily separate from the races. I've got boxes of record/super record parts........
Thanks mate! Much appreciated :)
 
PogoInTheWoods

PogoInTheWoods

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Nice to see things coming right along, Tom. An enjoyable and informative thread.
Not to derail the thread, but what are you using to cross reference part numbers between various saws that used the parts?
I find the last version of MediaCAT (before it was revamped) provides the best method for Stihl parts lookups and cross referencing the 'where used' information.

And speaking of derailed, my particular 045 re-rebuild was looking promising with the new case and crank I located. Pulled the crank to find the rod bearing in great shape. The main shaft bearings were rough and showed some funk and a little rust. They had to come off. They were perfect specimens for the USC treatment and actually turned out much better than expected with an initial cleaning and lube. I've certainly felt worse come out of running saws and was genuinely surprised at how smooth they were compared to their 'before' condition.

But to the derailed part. I bought a new 6004 for the original flywheel side case half and the existing PTO case half was fine with a smooth bearing and a brand new seal. The saw originally held vac and pressure indefinitely before the big end went. Cleaned up the newer crank with 20 micron lapping/finishing paper, got the top end and intake back together for leak testing and had a very, very slow leak somewhere. Turned out to be a first for me..., between the PTO side crank stub and the inside PTO bearing race itself.

Really. I swear to hell. Between the crank and the bearing. It does have the newer style bearing with the thinner outer race, but the inner races of both types are the same. So how does this even happen? The crank cleaned up nicely. No gouges. I thought I had the inner bearing race nice and clean to draw over the crank stub when pulling the case halves together. (I use the extended case bolts method, btw.) Is it possible that I removed enough material from the crank with the lapping paper to create enough relief between surfaces for the leak? It's my standard crank cleaning routine and this has never happened before.

Anyway, as a possible solution before tearing everything apart just to scratch my head further, I'm trying a sleeve sealing method using one of the Permatex Green low viscosity wicking thread lockers to see what happens. Application number one made a significant difference after sitting over night, though it didn't completely seal the leak. I drew a very small amount of the retainer between the shaft and bearing using a MityVac hoping it would follow the vacuum and set up fairly quickly.
The obvious concern is that it doesn't get into the case where it shouldn't be to cause an even bigger headache. I'll try another application today and see what happens. The good news is, there was another NOS bearing on ebay yesterday. The bad news is, the seller wants $90 for it. 'Course I'm not even sure the bearing is the problem. Didn't leak with the other crank. Sheesh.

045 Leak.jpg
 

J D

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Anyway, as a possible solution before tearing everything apart just to scratch my head further, I'm trying a sleeve sealing method using one of the Permatex Green low viscosity wicking thread lockers to see what happens. Application number one made a significant difference after sitting over night, though it didn't completely seal the leak. I drew a very small amount of the retainer between the shaft and bearing using a MityVac hoping it would follow the vacuum and set up fairly quickly.
I tried this a while ago on a 385XP with very limited success. Ended up pulling it apart & using loctite bearing retaining compound. I pressed the bearing right up to the shoulder on the crank & I suspect that ended up being where the compound sealed it. Haven't run the saw enough to know if I can call it a permanent fix yet
 
Gaudaost

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Thanks Pogo! Sorry to hear of your troubles! Being a wicking compound I’d wonder (Jerry / pioneer guy will know) if pulling the vacuum actually caused you to pull the wicking compound all the way through rather than allowing it to do its job and wick and stay. Maybe try just liberally applying it around the mating surface of bearing and crank and leaving it, in the morning wipe away all the excess. I’d be interested to hear how you go :)

Funny you should mention you had an air leak there. I took no chances and used loctite 609 retaining compound on the saw I’m rebuilding for this exact concern.
 

J D

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I had a saw that was leaking between the oil tank & crank case, put vacuum on it & dripped wicking loctite on the seam & it sucked it through but didn't fix it. Tried again with regular loctite & it worked. Again, haven't run the saw enough to say it's a perminant fix
 

Gaudaost

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I spent a little more time on the saw today,

I took all the parts off the ignition carrier plate and cleaned it well
4DFB41B2-4CCC-46A0-A949-BD66DD5FD5EB.jpeg

Removed the connector on the negative wire, stripped off the old damaged insulation, added new heat shrinkand added a new connector
B7ED0BCB-341D-43BF-8E9A-BBEA8FEF7CB7.jpeg

Then I removed the male connector on the kill wire and connected it onto a new piece of silicone wire as the old one was cracking. I soldered the slightly exposed wires as had been done from the fsctory and then filed it round and smooth for a good secure connection. I then added a new connector on the other end, crimped and soldered it, filed the excess solder away and tested it and got an excellent low resistance reading along the length.
411FCD16-0924-4D61-8D8A-0C58399EBD45.jpeg




Then I added the new HT lead after cleaning the ignition coil. Low side gave a perfect reading of 2.5 ohms of resistance. The High side was still giving me wacky high readings - 40koms. Even though I thought I had cleaned the armature plates well, I figured to go over them with a wire wheel. See through bits of plastic / adhesive started flying off everywhere and I then took a drill bit and scraped more plastic inside of the mounting holes. Retested the resistance and got 5.7km - perfect!
4B1C94E9-7A58-47B1-B4EB-F70DDF51C7C7.jpeg

I cleaned any oil residue that maybe on the new points and tested continuity and resistance, they were fine - made sure they broke cleanly too.
4C6CA9E4-BA60-4A27-8CDE-2D51C189D5F6.jpeg

I cleaned any possible oil off the new condenser and tested the capacitance which was within spec B02B1827-8267-4318-865F-6251A327E5DD.jpeg


Then I set up the dial indicator and the degree wheel, set timing to 27 BTDC and put it all back together!
11E0E2E8-9AB7-4785-A241-44CDCBB90C2F.jpeg

Bright blue spark
90E5B397-ED58-49DD-9357-6E6AB30620EC.jpeg

Here it is with all the new wiring and all set up without and then with the points cover.

ECDA8911-FDF1-4484-964A-EC52E221F0EE.jpeg 41283852-5419-437F-9CBF-CFF0F41765C8.jpeg
 
PogoInTheWoods

PogoInTheWoods

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Excellent work. Well done!

I'm afraid I may have backed myself into a corner with the wicking compound. I do have two grades and used both. Progress was made overnight, but not to my satisfaction.

Now comes the part where we find out how strong it actually is as a bonding agent when I try to push the crank out of the case while leaving the bearing in place -- without destroying a NLA (or otherwise very expensive!) bearing. If excessive heat is required to break the bond, I can obviously kiss the seal goodbye and probably the bearing as well. 500F is specified.

I hope to get to it yet today.
 

Gaudaost

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Excellent work. Well done!

I'm afraid I may have backed myself into a corner with the wicking compound. I do have two grades and used both. Progress was made overnight, but not to my satisfaction.

Now comes the part where we find out how strong it actually is as a bonding agent when I try to push the crank out of the case while leaving the bearing in place -- without destroying a NLA (or otherwise very expensive!) bearing. If excessive heat is required to break the bond, I can obviously kiss the seal goodbye and probably the bearing as well. 500F is specified.

I hope to get to it yet today.
Pogo, if it’s just a small leak you can tune out, is it not best to leave well alone? I fear you’re opening a can of worms including side loading the bearings and possibly destroying seals?
 
PogoInTheWoods

PogoInTheWoods

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I fear you’re opening a can of worms...
It's been open. More like a bag o' snakes now. LOL

If it were my saw I'd probably just run it as is for a fun saw/firewood saw. Problem is, it belongs to a fellow who bought it super cheap (non-running) for a small milling setup. He brought it to me to assess and possibly rejuvenate for his purpose. I did, and the rod bearing immediately failed. (there's actually a tech note about the needle cages failing). I felt obligated to make good on his trust in me and scrounged up a new crank to rebuild it again which is where I am now This'll be the third time I've had it apart down to the case and crank..., and hopefully the last. I'm so far under water with this saw it's ridiculous.
 
PogoInTheWoods

PogoInTheWoods

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Found a small, defective area on the inner race of the PTO bearing. Maybe some flaking when I pushed out the original crank? Used the heavier compound on both surfaces per the directions this time and slapped things back together. The original applications didn't wander too far inside the case. A little bit was still semi-liquid, but it had set up for the most part. Gave my splitter a run for the money. Will let this application set up for 24-48hrs. and see where it takes me.
 
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