Rebuilding a Stihl 034, should I try it?

dabills · Jul 23, 2019

Hi all, new to posting on this site, been a member for some time. I've been borrowing a buddy's saw for chopping up firewood but decided it's time to get my own. My grandpa is giving me a 034 that doesn't run, thinks it needs a new piston but who knows? Other than that he said it looks to be in good shape.

Having very little mechanical experience, do you think I'd be able to handle the project by myself? I'm relatively smart

so I can follow instruction I just don't want the project to drag on forever. Ive been researching a bit and don't know if I should go 034 again or upgrade to a 036. Any help is appreciated, thanks!

Nathan Graff · Jul 23, 2019

Why not? I think that manualslib should have a rebuild manual that you can download and print off. Some simple tools should do it. I"m sure that some others here with experience rebuilding that saw will help. I can't as I've never tried that saw. Although it might be less hassle to get an entirely new motor off of ebay. But look through the sections on how to diagnose a saw before tearing it apart. Vacuum testing, carb testing, removing the muffler to look at the piston, etc.

dabills · Jul 23, 2019

Nathan Graff said:
Why not? I think that manualslib should have a rebuild manual that you can download and print off. Some simple tools should do it. I"m sure that some others here with experience rebuilding that saw will help. I can't as I've never tried that saw. Although it might be less hassle to get an entirely new motor off of ebay. But look through the sections on how to diagnose a saw before tearing it apart. Vacuum testing, carb testing, removing the muffler to look at the piston, etc.

Thanks for the positive response. I'm halfway through a YouTube video and so far I think I can do it. I understand compression testing but have no idea how to do it, when to do it, and what tools are needed. I don't know what vacuum testing is but I'll research it.

cuinrearview · Jul 23, 2019

Run to an auto parts store and grab a T-27 torx screwdriver. Pull the four screws holding on the muffler cover. Take a pic of the piston through the exhaust port and post it up here.

cuinrearview · Jul 23, 2019

Where are you located?

cuinrearview · Jul 23, 2019

Oh, and yes. You should definitely repair it.

Nathan Graff · Jul 23, 2019

cuinrearview said:
Run to an auto parts store and grab a T-27 torx screwdriver. Pull the four screws holding on the muffler cover. Take a pic of the piston through the exhaust port and post it up here.

Are those T27 or 8mm? There's a fairly small list of tools needed to fix these saws really.

Compression test is how much pressure the piston builds up in the saw. Generally 100+PSI is required for the saw to run. To do the test, you take out the spark plug, and screw the tester fitting into the spark plug hole so that it seals. Then you pull the crank cord till the pressure stops rising.

Pressure and vac testing is different. There you block off all the ports, and use a tester and put 10 psi into the saw engine, and see if it looses pressure. Vacuum is similar you pull a vacuum, to see if the vacuum leaks. Often times, a saw won't run for a simple thing like a seal leak. Much cheaper to replace than a engine.

Spark test and carb tests are easier to watch videos about than to explain.

Hope this helps.

cuinrearview · Jul 23, 2019

Nathan Graff said:
Are those T27 or 8mm?

All of the screws take a T-27. The carb nuts I believe are 8mm. Flywheel nut should be 13mm or 1/2". The clutch is bigger, can't remember. Maybe 22mm? Some needle nose pliers and a small flat head screwdriver. That's about it.

dabills · Jul 23, 2019

According to the video so far they're all T27:

I'm going to watch videos of spark and carb tests. I'm at work so I can't do it right now I really should be working lol. How much approximately is the equipment for spark and carb testing, can this be bought at an auto store? Thank you all for your help so far I'm looking forward to this. Have yet to pick up the saw.

cuinrearview · Jul 23, 2019

You can test spark with no tools. Unscrew the plug, put the wire back on it. Make sure the switch is in the "run" position. Ground the plug body on the cylinder and pull the saw over. You will see spark jump the gap if there is any.

As far as "testing" the carb, really the only way to do that is on a running saw. You can test the pop off pressure for the needle with any pressurized air source and a regulator and gauge. If you want to invest in it a pressure and vacuum tester is a good investment. You can perform other tests with that.

dabills · Jul 23, 2019

Ok I'm crystal clear on spark test but will have to research a bit more to understand carb test. Thanks this information is invaluable.

cuinrearview · Jul 23, 2019

This is how I would go about it:
-pull muff and check condition of piston
-If good, pull plug and dump a little mix in the cylinder. Re-assemble and try to start it. If it pops or runs a little you have good compression and spark. I do this first to avoid wasting or having to dump fuel back out if you have to tear it down.
-If it doesn't pop, check for spark as described above. If you have good spark the timing is off or your compression is low.
-If it does pop, put some fuel in the tank and try starting it like normal.

md1486 · Jul 23, 2019

I have replaced P&C on a 034 last year with minimal experience. I put a 036 P&C instead. Really not that hard. Take your time and you should be ok. One year later I have rebuilt 6 or 7 saws. Im still far from an expert though.

Wood Doctor · Jul 23, 2019

The Stihl 034 was the second saw hat I ever rebuilt. I upgraded it to an 036 top end and added an outside bumper spike:

I ran it today and brought in a truckload of wood ready to split. This saw was missing a few other pieces when it was given to me, including the clutch cover.

Totembear · Jul 23, 2019

Clutch is 19mm. The way to learn is one step at a time. The first thing I would do is pull the muffler and look at the piston. If it looks good its time to go on to something else. It could be something simple like fuel line, broken boot, or impulse line. There are many different things that could make a chainsaw not run. Are you going to start working on chainsaws or is this a one time project? You can have some money into tools if you work on them alot. If not, it might be cheaper for you to take it to a shop to pressure and vacuum test it than to buy a mighty vac to do it. This is the place to ask questions. An 034 is not difficult to repair, just if its the oil pump that sucker takes some time. Take plenty of BEFORE pics, they can save you alot of headaches if you get to a point where you are unsure of what goes where.

dabills · Jul 23, 2019

cuinrearview said:
Where are you located?

Just saw this, I'm between Buffalo and Rochester NY

SteveSr · Jul 23, 2019

Be aware that there is an Old and New version. The dividing year is about 1995/6. Put up some pics of the back of the saw both with and without the AF cover on and we can tell you which version you have.

I am currently rebuilding an 034 Super I couldn't walk away from. It is vintage 1993 so an early version. So far I haven't had an issue finding parts but the cost adds up! With a saw this old all of the rubber (including crank seals) is questionable.

Your saw died for a reason. Your job is to do through forensics to keep it from happening again!

scallywag · Jul 23, 2019

cuinrearview said:
Run to an auto parts store and grab a T-27 torx screwdriver. Pull the four screws holding on the muffler cover. Take a pic of the piston through the exhaust port and post it up here.

Do the above first!