Stihl 028AV Super rebuild.

[OH_Varmntr]

Dad's 028AVS was really starting to lack power the last few times he cut with it. It hasn't had the carb touched in 6, if not 8 years. I rebuilt the carb but couldn't get it to tune. Typical air leak symptoms.

Upon removing the recoil assembly, it was apparent that we had multiple bottom end issues.


First she's getting a thorough cleaning followed by new AV bushings, crank bearings, seals, gaskets and a new pop-up piston and rings. All parts are OEM aside from the USA-made base and case gaskets and the Italian-made Meteor piston.

Everything is in except for the piston, so let's get started by disassembling the saw and giving her a thorough cleaning. She's pretty clean to start with.

Mount the flywheel puller and get it out of the way. Piece of rope works great for a piston stop.

A little tappy tap tap...

Yep, nearly the entire outer lip is gone from the recoil side seal.

Clutch time. 19mm socket with the face ground so it can properly engage the flywheel flats on a 1/2 ratchet going righty loosey here.


I like to knock out the case alignment pins as it helps the cases fly apart when you smack them with a mallet.

A little heat to the PTO side bearing housing and a few good smacks with a rubber mallet and bingo, we have separation.

Something is very wrong here.
This could make getting the outer race out of the case a difficult task. But don't lose the ball bearings!
Stuff them back into the bearing and put the inner race back in. That way we can use the inner race to press the outer race out in the press. Viola!

 

[OH_Varmntr]

She's had a hard life.

Well now I got a bit ahead of myself and forgot to take some pics. After cleaning the cases up in a bath of diesel fuel, I installed the PTO bearing on the crank, heated the PTO side case half and dropped the crank in the case.

From there I heated up the flywheel case half bearing house and dropped that bearing in, installed the case center gasket, heated up the flywheel side bearing inner race and dropped it on the crank. It went on far enough to get good thread engagement on the case bolts so I used them to carefully draw the cases together.

Then the seals got installed.


Now the clutch. Lefty tighty.

The piston was badly worn and the exhaust side was scored enough that I didn't feel comfortable reusing it. It had enough skirt wear on the exhaust side that it's not worth the risk and the exhaust side crown was getting a burr. Pretty interesting that the rings were still free and luckily no transfer to the cylinder so it will clean up nicely and get a new piston and rings and be ready for another 44 years of cutting wood.

 

[alexcagle]

Great presentation.
One of my favs, soop'a

 

[ozziechainsaw]

She's had a hard life.
View attachment 1072164
Well now I got a bit ahead of myself and forgot to take some pics. After cleaning the cases up in a bath of diesel fuel, I installed the PTO bearing on the crank, heated the PTO side case half and dropped the crank in the case.

From there I heated up the flywheel case half bearing house and dropped that bearing in, installed the case center gasket, heated up the flywheel side bearing inner race and dropped it on the crank. It went on far enough to get good thread engagement on the case bolts so I used them to carefully draw the cases together.

Then the seals got installed.
View attachment 1072165
View attachment 1072166
Now the clutch. Lefty tighty.
View attachment 1072167
The piston was badly worn and the exhaust side was scored enough that I didn't feel comfortable reusing it. It had enough skirt wear on the exhaust side that it's not worth the risk and the exhaust side crown was getting a burr. Pretty interesting that the rings were still free and luckily no transfer to the cylinder so it will clean up nicely and get a new piston and rings and be ready for another 44 years of cutting wood.
View attachment 1072168

That looks much cleaner now. What type of Piston did you end up getting for it ?

 

[OH_Varmntr]

That looks much cleaner now. What type of Piston did you end up getting for it ?

I ordered a Meteor pop-up.

 

[Mad Professor]

When I first saw the bearing I thought where to hell did the balls go to?

Then realized they must have popped out when you split things.

Those are great old saws built better than a tank. Glad you are restoring it.

I've had one since the 1980s. My 026s are lighter but I think the 028S just as strong and built to last longer. Sort of like 038M vs 044.

 

[OH_Varmntr]

Yep my 026 is lighter but I love the bigger 0-series saws. This was one of my first saws that I got in a box of parts. Ended up being 2 different 028s, this Super and a Wood Boss. The WB has a point ignition but I've never assembled it and got her running.

I've got the Super back together as far as I want to get her without having the piston.

 

[HarleyT]

where to hell did the balls go to?

I say that about a lot of guys these days.

 

[OH_Varmntr]

Meteor piston with Caber rings and stock-style circlips.

All set and ready to go.

Starts and idles great. I haven't thrown a tach on it yet, I just ran it a bit rich and tried tuning it in the wood. At 3/4 throttle and below it runs strong but try holding it WOT and it has what sounds like 4-stroking but the RPMs wander quite a bit while doing so. I've never heard this in a saw before, it's interesting. I don't think it's an actual 4-stroking condition, it's something else.

I'm going to order the specific carb kit from Stihl to make sure I have the correct metering lever spring for it as the original was damaged and the replacement we had in the universal kit didn't look right. The original was a constant rate spring vs the kit spring was a variable rate spring.

 

[xtremez]

Did the carb kit fix the wandering RPM?

 

[Sidecarflip]

Have one just like it that I bought new 40 years ago and never been rebuilt but I don't use it all that much anyway. Mine was getting finicky about idling until I switched it to synthetic (Echo Red Armor 50-1) and now it idles no issue. Remember, it's an RPM saw and they love to rev. Run a 20" greaseable roller nose Stihl bar with 325 chipper ground at 30 degrees. Bought the 090 and the 075 at the same time.

 

[Cascadium]

I have one of those too that my Father-in-law (RIP) bought new. I like to use it, it reminds me of him.
Having a little trouble with it but I'll get it fixedc I think.
Usually I win in challenges with small motors but.....???
I will check if the crank bearings have slop.

 

[Sidecarflip]

Mine (45 year old 028) was having base idle issues until I switched to canned fuel and that cleared that right up. Great saw for being ancient.

 

[billyboy]

I have owned 1st and 2nd version and have a super now. Great saws, just seem to keep going with minor maintenance. Clean it up and keep the gas fresh.

 

[OH_Varmntr]

Did the carb kit fix the wandering RPM?

No, but a new gas tank vent hose with grub screws did. When running the saw on its side it leaked gas into the filter box and really richens the mixture.

Dad has ran it multiple times since and is happy as can be.

 

[Mad Professor]

The tubing with grub screws is such a simple vent system that works well and easy to fix with readily available parts.

They can get plugged if the air box is filthy/never cleaned, and the tubing eventually deteriorates.

It took > 30 years for the latter on one of my 038s. Hardware store had generic fuel line that fit and reused the grub screws. No need to go to $tihl dealer who are very proud of their part$.

No, but a new gas tank vent hose with grub screws did. When running the saw on its side it leaked gas into the filter box and really richens the mixture.

Dad has ran it multiple times since and is happy as can be.

 

[ZeroJunk]

The tubing with grub screws is such a simple vent system that works well and easy to fix with readily available parts.

They can get plugged if the air box is filthy/never cleaned, and the tubing eventually deteriorates.

It took > 30 years for the latter on one of my 038s. Hardware store had generic fuel line that fit and reused the grub screws. No need to go to $tihl dealer who are very proud of their part$.

We get something insane like $15 for those things. I took a piece of fuel line, put a plain old screw in it, cut the screw off and gave it to an old man the other day.

 

[Mad Professor]

We get something insane like $15 for those things. I took a piece of fuel line, put a plain old screw in it, cut the screw off and gave it to an old man the other day.

Remember, don't screw the Grub screw(s) in , push it. Otherwise it cuts tubing and won't vent.

Love my 038'S and 028S.......¢