Stihl 024AV rebuild/repair questions

[Woodcutter_Mo]

 Hello, I shelved my old Stihl 024 several years back because it was getting low on power. Recently I got it out and decided to see if I could get it running again just for a project, and it would be a good little limb saw. I figured I'd start this thread for the questions I have trouble finding on the net.
I checked the compression and it is low at around 110 psi. I plan to atleast replace the rings and possibly crank seals ect.

My first question since I have the cylinder removed, what do I look for when checking the condition of the rod bearings?

[moodnacreek]

Twist the wrist pin end to check for play. [of the rod]. Sthil lower ends last a long time.  You can almost always do one cylinder replacement.

[Woodcutter_Mo]

 Ok, I'll check that. If I do just the rings I might go ahead and replace the wrist pin and bearing just to be on the safe side. I can rock the connecting rod back and forth a bit on the crank, is that normal? Other than that the crank (case) bearings feel good and tight. 

[HolmenTree]

Your best to install a new piston too which comes complete with a new wrist pin and bearing along with rings. If your rings are worn bad the piston's ring grooves probably are too.
With the piston removed hold the connecting rod at tdc ,hold the flywheel solid and try pushing and pulling up and down on the connecting rod. There should be no play in the lower bearing. Side play is normal.
Normally OEM cylinders come matched with a piston. But if only the piston is to be replaced make sure it's marked "B" on the crown (according to the manual)
I'm just looking at a Stihl 024 service manual I kept from the days when I worked for Stihl.


  

 

[Woodcutter_Mo]

 Thanks for the info and pics, I'll check that out tonight. I bet that's handy having OEM shop manuals, I'd like to find some someday.

I found a Meteor piston and rings kit that comes with the wrist pin and clips for a good price that I may buy for it. From what I've read so far, they sound like a trusted aftermarket saw parts company. I'll find out and make sure it can be used with a used OEM cylinder.

[Woodcutter_Mo]

 Just an update, I ordered the piston, rings, wrist pin and clips kit that I had found for a good price. I also ordered a ring compressor kit and a mityvac pressure/vacuum tester and a new cylinder gasket. Today I will call the local dealer and price a set of new crank seals, from what I've read it's best to use OEM crank seals.

EDIT: The Stihl dealer got me a set of crank seals ordered. Can't wait for everything to get in so I can start wrenching  8)

[Woodcutter_Mo]

 The vacuum/pressure tester came in along with the new base gasket. Just waiting on the piston and rings kit, ring compressor kit, crank seals and need to get a new wrist pin bearing. Getting closer 



I checked the play in the rod bearings, there isn't any noticable play up and down so that should be fine then. I soaked cylinder in carb cleaner to hopefully help remove the carbon. We'll see what happens

[Woodcutter_Mo]

 When vacuum and pressure testing the saw, how long should it hold on the gauge?

[Woodcutter_Mo]

I ended up finding some info on pressure testing the crank case. For future reference, to my understanding it it should maintain around 14hg of vacuum and 8psi of pressure for around 30 seconds.
When I tested the saw today, the needle dropped some in the 30 seconds, I may need to rig up a better block off for the exhaust port and test it again.
I got the piston replaced and the saw is re-assembled minus the carb as I took it back off and re-sealed it. The saw was still losing power after a few minutes of running so tomorrow I'll see if the carb helps and do some more trouble shooting and air leak testing.

[Mad Professor]

Just an update, I ordered the piston, rings, wrist pin and clips kit that I had found for a good price. I also ordered a ring compressor kit and a mityvac pressure/vacuum tester and a new cylinder gasket. Today I will call the local dealer and price a set of new crank seals, from what I've read it's best to use OEM crank seals.

EDIT: The Stihl dealer got me a set of crank seals ordered. Can't wait for everything to get in so I can start wrenching  8)

Too late now but....
You get a better deal from stihl buying the whole gasket set that comes with the crank seals

[Woodcutter_Mo]

Just an update, I ordered the piston, rings, wrist pin and clips kit that I had found for a good price. I also ordered a ring compressor kit and a mityvac pressure/vacuum tester and a new cylinder gasket. Today I will call the local dealer and price a set of new crank seals, from what I've read it's best to use OEM crank seals.

EDIT: The Stihl dealer got me a set of crank seals ordered. Can't wait for everything to get in so I can start wrenching  8)

Too late now but....
You get a better deal from stihl buying the whole gasket set that comes with the crank seals

Well I'll keep that in mind next time then, thanks

[Woodcutter_Mo]

 Over the weekend I got the new piston, rings, base gasket, and carb re-sealed kit installed. The saw is running better than it was but still very erratic, I believe the crank seals may be the culprit.

I made a better exhaust block off for testing and the saw holds 8-10 psi no problem but the needle slowly goes down when pit under vacuum. I will replace the crank seals, impulse line and fuel line when they come in and report back with my results.

[Woodcutter_Mo]

 The new crank seals came in along with the new fuel line and impulse line. I got the sprocket side seal replaced no problem but the flywheel side is being a real pain... Too small to get ahold of and I've torn it up prety bad. Hopefully I don't end up having to open the case to get it out. :(

[Al_Smith]

Take a sharp prick punch,sharp awl and punch a small hole in the metal portion of the seal .Then use a drywall screw to pull it out.

[millwright]

One thing to check on the smaller saws is the screen in the muffler. It can get plugged and cause erratic running and power loss.

[Woodcutter_Mo]

Take a sharp prick punch,sharp awl and punch a small hole in the metal portion of the seal .Then use a drywall screw to pull it out.

That method worked good on the clutch side, but the the metal just keeps tearing out on the small seal on the flywheel side, that 33 year old seal is really stuck in there  . I'll mess with it a little more but I have a feeling I'll be fabing up a case splitter this weekend and getting a new crank case seal ordered.

One thing to check on the smaller saws is the screen in the muffler. It can get plugged and cause erratic running and power loss.

Thanks for the reply, the screen looks good. I took the muffler appart cleaned it out when I replaced the piston and rings and since then I've also tried it with the screen removed and it was still acting up so I believe I can rule that out.

[Canadiana]

Way to go woodcutter. I'm really enjoying the documentation of your process. The best process for me to read about is a long one that doesn't have easily diagnosed symptoms. Best of luck with your rebuild. Keep those updates coming

[Woodcutter_Mo]

 Canadiana- Thanks, I'll need all the luck I can get since this is my first nearly complete chainsaw tear down. Glad your enjoying the thread.

I decided that I will probably end up damaging the crank case if I pry on the seal any more so tonite I ordered a gasket kit and prety much have the saw torn down and am ready to split the case once I get some kind of case splitter put together.

[Woodcutter_Mo]

 I got busy with a bunch of other stuff and havnt had time to make a case splitter tool so I ordered a Husqvarna style splitter tool. It should be here in a couple weeks hopefully.

I've got another question.. How many crank case screws are there? I got the 3 around the crankshaft and the one at the top of the oil tank at the front of the saw, and looking at the new gasket there appears to be 2 more holes at the bottom of the oil tank. One appears to be an alignment dowel pin (lowest hole) but not sure about the one just above it. I assume that's a screw? It's packed with crud and some corrosion so I can't tell if it's a screw or another alignment pin.

[limbwood]

there is a pin and another screw next to lower spike bolt

[Woodcutter_Mo]

there is a pin and another screw next to lower spike bolt

Ok, I guess I'll see if I can get that crud dug out of the recess so I can get to the screw. Hopefully it's not corroded to the point that the torx driver can't grip it. We'll see. Thanks

[Al_Smith]

A fact I did not know until it was pointed out to me that the 024-026 came with three different styles of mufflers ,highly restrictive ,medium and low .My 024 was the most restrictive but with the help of a die grinder and about 20 minutes I alleviated that problem.

[Al_Smith]

A PS on the above .When I got the saw from a "dead" pile at a dealer it ran,the exhaust side of the piston was a little scorched not badly .Evidently from the restrictive muffler and likely from the tuning.Perhaps the oil mix but I won't elaborate on that .I didn't do a thing to the saw except gut the muffler and retune and it runs great for a little itty  bitty saw .

[Woodcutter_Mo]

 The muffler on this saw looked fairly restrictive, it had 4 small holes at the outlet. I trimmed out the holes to 1 larger hole. It did seem a little more "peppy" but was hard to really tell with he apparent vacuum leak. I do know it made it sound a bit different , wasn't alot louder but it has a much deeper tone like a bigger Stihl.

[Al_Smith]

Being somewhat of an outlaw when I redo a muffler all that is left is the shell .They aren't as loud as some might think .