Need help with Stihl 031AV

[mattinky]

I'm trying to get the crankcases apart to get the crankshaft out of a 031AV and man are they tight! I can't get them to budge, this is the first Stihl I've worked on, do I need a puller/seperator/special tool of some sort?
Thanks, Matt

 

[stihltech]

stihl case

The case will need to be heated to come off the crank bearings. The safest way to do this is to use a heat gun.

Just so you know, this will be a learning experience. Ask lots of questions.

 

[Lakeside53]

Get a service manual... Look at how it is supposed to be done, study the IPL and figure out what has to be done to get it apart, and back together. Then either borrow the right crankcase tools (hard to find...) or make a puller/pusher out of and old clutch center, small puller, and various lengths of bar and pipes (it's how I started).

Don't stick screwdrivers or whatever in between the case halves...

I don't subscribe to the heat method for disassembly...

Hint - the crank shaft is PUSHED out of the casings basically by a threaded rod attached to a bar that clamps to the bar studs.. . You can also use a standard 3 arm puller to push the crank out by locking the arms to the bar, and pushing on the crank with the center... now go find a manual, and have fun!

 

[stihltech]

crank

Ok, Then how do you get the bearings out?

 

[Lakeside53]

Press them out cold. They just come straight out. You can even use a vice with a socket to push if you dont have a simple press.

They go in with heat (300F - and they are just placed with finger pressure) before the crank is inserted, but many just press them in cold.

 

[stihltech]

press

Guess you have never had an 056 crack or press the bore liner out on the clutch side.
But, they got away from that with the newer saws.

 

[PES+]

031s are the same as the 056 heat is required to remove and install but you can try to just press them and you very likely will distort or crack the case

 

[Lakeside53]

You don't crack the case if you support it evenly... Press the bearing out towards the center... - the flat case joint is an excellent support. Use a backing support of you are concerned.

Use heat for putting the bearing in - finger pressure (or none) required on saws similar to 031 or where they are just inserted in the mag casing. The clutch side of the likes of an 036 type, upwards is another problem - it has a steel liner cast into the magnesium than even when baked at 300F (convection) for 20 minutes, and the bearing frozen, still requires a press. These I press in backwards (towards the inside) then mount the oil pump and "adjust" (press) back out. My 088 clutch side was a nightmare to install, and the cost of failure way too high... I made a back support (fits in around the bearing on the machined casing - just like the factory uses) out of piece of schedule 80 Iron pipe with the end turned to the right diameter.

I've never cracked a case... I've done lots of other stupid things, but not that.. yet..

 

[Lakeside53]

Guess you have never had an 056 crack or press the bore liner out on the clutch side.]But, they got away from that with the newer saws.

Nope, I haven't...

The pro saws (except 026 and early 034) all have a steel insert on the clutch side... and you'd have to destroy the case to remove it as it integrally cast.

I use a 2 or 3 ton arbor press, not hydraulic. This way I can feel what's happening. I have access to a 25,000 lb (real nice!!!!) hydraulic press than can press or destroy anything, but don't use it on saw motors...

I don't have a problem with the use of heat in removing bearings once the crank is removed - I just find it unnecessary, and on the saws with steel liners on the clutch sides - it does't do much good as the liner expands at a similar same rate as the bearing.