Stihl 034 Crankshaft Seals & Tune-Up?

[ReggieT]

Hey Guys,
Been a second since I've posted, but I ran upon a great deal on a 034 that "supposedly" only needs crankshaft seals.
My Stihl Tech offered it to me for $150 up & running or $42 OTD AS IS...I opted for the latter!!
I finally dug into it bit tonight and was surprised at under the grime was a pretty decent saw.
Bar is in good shape, the chain is semi-sharp chisel, piston looks smooth,...and its cleaning good so far.
This is my first time really ever digging this far into a saw and the progress is arduous, yet kinda intriguing!

I'm leaning toward letting Tech friend do the seals @ his house for $25...I can handle the tune-up though.
Here are some pics of what I've found thus far...any suggestions and thoughts of what else I might replace while I'm at it?

Thanks & Happy New Year!
Reg

 

[Jon1270]

Nice, that's the model I started my hobby with too. I got mine for free but it was in worse shape. On mine, the owner had overtightened the chain and destroyed one of the bearings, which in turn destroyed the crankcase. That was an expensive problem to fix! Yours appears to be a much better deal.

That saw wasn't used much. Chances are, most of what you'll find wrong with it is degraded rubber parts. If your tech has already done some simple tests and determined that the crank seals are bad then that's a fine place to start. Changing seals without specialized tools is kind of fiddly, so having your tech do it for you is a good idea. I'd ask if he would then vac and pressure-test the saw to make sure there aren't other leaks, since you probably don't have the tools to do it yourself.

Look carefully at the rubber AV buffers. If cracked or torn at all, then replace. This is not just about comfort; when AV buffers tear loose, the relative positions of the tank/handle assembly and motor can shift under strain, and do other damage.

Check the condition of the fuel and impulse lines. Even if they're not leaking now, chances are they've either stiffened with age or gotten gooey. Replace unless they're in such nice, supple condition that you suspect they are younger than the rest of the saw.

Pull the clutch drum and take a peek at the oil pump exit hose. it doesn't have to be soft and flexible because it doesn't move during operation, but make sure it's intact. When reinstalling the clutch drum, make sure the bearing is in good condition, and grease it.

Clean the air filter, and make sure its in good condition, too.

Dig up an illustrated parts list for it. The exploded diagrams are helpful for understanding how things go together, and the part numbers are very handy to know when you're ordering (or searching eBay) for replacements.

 

[ReggieT]

Nice, that's the model I started my hobby with too. I got mine for free but it was in worse shape. On mine, the owner had overtightened the chain and destroyed one of the bearings, which in turn destroyed the crankcase. That was an expensive problem to fix! Yours appears to be a much better deal.

That saw wasn't used much. Chances are, most of what you'll find wrong with it is degraded rubber parts. If your tech has already done some simple tests and determined that the crank seals are bad then that's a fine place to start. Changing seals without specialized tools is kind of fiddly, so having your tech do it for you is a good idea. I'd ask if he would then vac and pressure-test the saw to make sure there aren't other leaks, since you probably don't have the tools to do it yourself.

Look carefully at the rubber AV buffers. If cracked or torn at all, then replace. This is not just about comfort; when AV buffers tear loose, the relative positions of the tank/handle assembly and motor can shift under strain, and do other damage.

Check the condition of the fuel and impulse lines. Even if they're not leaking now, chances are they've either stiffened with age or gotten gooey. Replace unless they're in such nice, supple condition that you suspect they are younger than the rest of the saw.

Pull the clutch drum and take a peek at the oil pump exit hose. it doesn't have to be soft and flexible because it doesn't move during operation, but make sure it's intact. When reinstalling the clutch drum, make sure the bearing is in good condition, and grease it.

Clean the air filter, and make sure its in good condition, too.

Dig up an illustrated parts list for it. The exploded diagrams are helpful for understanding how things go together, and the part numbers are very handy to know when you're ordering (or searching eBay) for replacements.

Appreciate...great info...I'm on it.
Will update...School starts back Monday, so I may let him go all the way through it...as I'll be running wide open Mon-Thur...and I have some Hickory trees to harvest this coming weekend.

Thanks,
Reg

 

[ReggieT]

How much pain or trouble is it to swap out crankshaft seals?

 

[Jon1270]

How much pain or trouble is it to swap out crankshaft seals?

It's doable, but a big enough PITA that it would be well worth paying someone else $25 to do it. Installing replacements is easy, but getting access to them takes a bit of work and removing the old ones safely without specialized tools takes some finesse.

Getting access requires removing the flywheel (much easier and safer with the proprietary Stihl flywheel puller tool and a piston stop), clutch (piston stop and 19mm socket) and oil pump (T27 driver). Once you get that far, you should clean the area around both seals to reduce the risk of dropping debris into the open bearing.

If you don't own the ridiculously-expensive Stihl seal pulling tool then the most common method is to use an awl to poke (NOT drill) holes in the metal parts of the seals and thread in small sheet metal screws to pull on. That's tricky on the flywheel side because the seal there is very small, and a sharp steel screw can easily scratch the magnesium seat. The clutch-side seal is larger, and less risky to mess with because it fits inside the hardened steel bearing race.

The new seals are simply tapped into place. An appropriately-sized socket or piece of tubing (cut square) can substitute for the official tool.

 

[ReggieT]

It's doable, but a big enough PITA that it would be well worth paying someone else $25 to do it. Installing replacements is easy, but getting access to them takes a bit of work and removing the old ones safely without specialized tools takes some finesse.

Getting access requires removing the flywheel (much easier and safer with the proprietary Stihl flywheel puller tool and a piston stop), clutch (piston stop and 19mm socket) and oil pump (T27 driver). Once you get that far, you should clean the area around both seals to reduce the risk of dropping debris into the open bearing.

If you don't own the ridiculously-expensive Stihl seal pulling tool then the most common method is to use an awl to poke (NOT drill) holes in the metal parts of the seals and thread in small sheet metal screws to pull on. That's tricky on the flywheel side because the seal there is very small, and a sharp steel screw can easily scratch the magnesium seat. The clutch-side seal is larger, and less risky to mess with because it fits inside the hardened steel bearing race.

The new seals are simply tapped into place. An appropriately-sized socket or piece of tubing (cut square) can substitute for the official tool.

YIKES!!...all that attention to detail & jargon has my noggin dizzy...$25 So let it be written. So let it be DONE!

 

[woodhog73]

Clean saw. Looking at the picture showing the muffler off and piston exposed looks great no scoring at all I'd say for if you paid $45 bucks you got a great deal ! No take that back you stole it ! If it only needs new seals no problem easy fix then you've got a saw you can run it for a long time or sell it and make a few bucks easy. Did you test the compression on it ?

Not to be disrespectful on repair time but the entire saw can be torn down and rebuilt in under an hour that's why your tech friend can sell it so cheaply. If your looking to rebuild it yourself it looks like a nice project. Or for $25 to your buddy that's a no brainer too. If it were me I'd do the rebuild myself considering the risk is low, you only paid $45 plus cost of parts. ( minimal ) but everyone is different .

 

[ReggieT]

Clean saw. Looking at the picture showing the muffler off and piston exposed looks great no scoring at all I'd say for if you paid $45 bucks you got a great deal ! No take that back you stole it ! If it only needs new seals no problem easy fix then you've got a saw you can run it for a long time or sell it and make a few bucks easy. Did you test the compression on it ?

Nope...haven't done it. Appreciate ze compliments.

 

[woodhog73]

Does the saw run ? Bad crankshaft seals will not effect compression. But bad crankshaft seals will cause a lean run condition because of the introduction of air not compensated for by the carburetor. If the saw runs, put a new plug in it see what color the plug is. See how it runs, if it idles , runs well, throttles up with no hesitation off idle , runs wide open in the cut, and the plug maintains a brown ( not white ) color ( or black plug for that matter ) then I'd question who ever told you the seals are bad.

The seals may be bad but the condition of the saw and the piston shown in pictures I'm struggling with the crank shaft seals being bad. I've seen 40 year old saws from the early 70s beat to heck and the seals and main bearings were fine . Your saw hardly looks used.

 

[Jon1270]

Even if you only paid $45 for it, there's more at risk because you are unlikely to find another at that price anytime soon. Otherwise I agree with Woodhog that bad crank seals are pretty rare. In the last few years that I've been working on saws I have removed seals to facilitate cleaning out debris when a crankcase has been contaminated, and I've installed new seals with new bearings a couple of times, but I'm not sure I've found a single leaking crank seal on a Stihl professional saw. Cracked manifolds and impulse lines, yes, but not crank seals. I did recently find one on a Husqvarna...

Have you tried to start it? If so, how did it behave?

 

[ReggieT]

Does the saw run ? Bad crankshaft seals will not effect compression. But bad crankshaft seals will cause a lean run condition because of the introduction of air not compensated for by the carburetor. If the saw runs, put a new plug in it see what color the plug is. See how it runs, if it idles , runs well, throttles up with no hesitation off idle , runs wide open in the cut, and the plug maintains a brown ( not white ) color ( or black plug for that matter ) then I'd question who ever told you the seals are bad.

The seals may be bad but the condition of the saw and the piston shown in pictures I'm struggling with the crank shaft seals being bad. I've seen 40 year old saws from the early 70s beat to heck and the seals and main bearings were fine . Your saw hardly looks used.

Woodhog,
Much obliged...gonna put her back together in the morning...slam a new plug in and see what happens...will give a detailed report on the particulars.
I like your optimism for sure!

 

[ReggieT]

Even if you only paid $45 for it, there's more at risk because you are unlikely to find another at that price anytime soon. Otherwise I agree with Woodhog that bad crank seals are pretty rare. In the last few years that I've been working on saws I have removed seals to facilitate cleaning out debris when a crankcase has been contaminated, and I've installed new seals with new bearings a couple of times, but I'm not sure I've found a single leaking crank seal on a Stihl professional saw. Cracked manifolds and impulse lines, yes, but not crank seals. I did recently find one on a Husqvarna...

Have you tried to start it? If so, how did it behave?

I concur...I'm on it tighter than slob on a baby!!
I see them on the cheap quite a bit, but I'm well connected to a lot of dealers, tree service studs, forestry buds, run a ton of Craigslist alerts, and frequent auction/liquidation sales galore.
Just passed on a 034 Super for about $50...026 need a jug/piston for $40, looking @ a 143 Sachs Dolmar w/30 bar for about $75 "supposedly" is a screamer....etc, etc

I'm about to enroll in a small engine repair school...and hopefully eliminate the shop/chainsaw gurus.
I love chainsaws to much to remain a dunce about them.
Normally I'm a fairly quick study academic wise...hopefully that will translate to some decent hands on know how!
Thanks for all of the wonderful tips & advice.

Later,
Reg