028AV Super Report and Question

[MerleM]

Hey Fellas,

This weekend I found time to go thru my new (to me) 028 Super. It cleaned up pretty nice for the most part. I discovered that the oil pump had a bad leak and had thoroughly oiled down the area inside of the plastic cover that houses the clutch and brake mechanism. What a mess!

So...I pulled the pump and found that the plastic plug that fits in the aft end of the housing was loose and worn. I was able to get a new one from my local dealer and also picked up the seal for the input shaft. Those parts went in pretty easily, and then I used two cans of Brake / Parts cleaner to clean all the oil out of the clutch and brake assembly.

When I had the muffler off I took a look at the piston and am not sure if what I'm seeing is "normal" wear and scratches, or if I'm dealing with a badly scored piston. I took a picture, it's not the best, but hopefully can see what I'm talking about. Also here's a couple pictures of the cleaned up saw put back together.

It seems to run quite nicely, I just wonder if the condition of the piston is going to be a power robber and should be replaced. I didn't put my compression tester on it yet, but plan to do so and will report back with the results.

Thanks for any opinions you guys might have!

 

[blsnelling]

I hate to be the bearer of bad news, but that does not look good. I'm going to guess that it's scoring from carbon build up. Take the jug off and see if 0000 steel wool will polish it up. If it's just from carbon, I'd guess the cylinder will look good. Make sure you clean out that exhaust port and the crown of the piston good.

 

[MerleM]

Thanks. the more I look at it, and compare with other pictures of scored pistons, I agree, it doesn't look good.

I just went out to the shop and did a compression check on it. I was able to get a high reading of 160 psi, that was after several (maybe 5 or 7) hearty pulls on the rope.

Is there a limit to how many times you can pull the rope to take your reading, or is it simply the highest number you can get, regardless of whether it takes two pulls or ten?

Andy

 

[blsnelling]

Pull until it won't go any higher.

If you've got that kind of compression, you're likely in good shape. I would not run it again until I got all that carbon cleaned up though. You'll need a new base gasket, and if you want, new rings. That wouldn't be required though. I'd remove the existing rings even if not replacing them and clean real well in the grooves. If you're replacing them, just break a piece off the old rings and use it to carefully clean out the grooves. Take care not to woller them out though. I'd also polish the piston with 0000 steel wool, rather than sandpaper.

 

[teacherman]

What did you give for it? (or is it bad etiquette to ask?)

I just got an 029 Super for 86.00, supposedly runs strong but won't idle well after an employee took it home to adjust the carb

I can hear it now: "Ha! You fell for that line?!" :bang:

 

[Lakeside53]

Ha, you fell for that line:greenchainsaw:

 

[Lakeside53]

The apparently decent compression may be due to excessive carbon... Tear it down..

 

[adkranger]

Nice looking 028. Like Lake & Brad said, pull the P/C for inspection and clean up. I'll bet that the cylinder will be fine after clean up, but you're probably going to want a new piston/rings.

For some reason my 028s run the highest, consistent compression readings out of any of my saws. Don't know why, they just do.

 

[MerleM]

Teacherman - I don't mind you asking, I paid 150 for the saw. I think it's a fair price, not a screaming deal, but after going through it, I don't feel like I got ripped off either. With the oil pump repair I'm into it about 170 at this point.

I'll look into pulling the cylinder off and having a look. I've never torn that far into a saw, but after investigating, it seems pretty do-able for my skill level. I just need to get some sort of low profile 90 degree Torx T-27 wrench to remove the cylinder to crankcase bolts.

Is there a special tool needed to compress the rings for re-installation? I'm guessing with a ring that small that it can be done (carefully) by hand, but let me know if there's a tool I need to invest in first.

Thanks everbody!

Andy

 

[Lakeside53]

The bolts are removed through the holes in the cylinder.

If you haven't done this type of work before.. time to get a service manual. Even one from an 026 will give you all the important points. I'm sure someone on AS can send you one.

A new quality piston/cylinder set from Tecomec is around a $100.

 

[adkranger]

I'll look into pulling the cylinder off and having a look. I've never torn that far into a saw, but after investigating, it seems pretty do-able for my skill level. I just need to get some sort of low profile 90 degree Torx T-27 wrench to remove the cylinder to crankcase bolts. Don't pinch pennies here, get a good quality wrench.

Is there a special tool needed to compress the rings for re-installation? I'm guessing with a ring that small that it can be done (carefully) by hand, but let me know if there's a tool I need to invest in first.

Thanks everbody!

Andy

Andy, you just need a long shank T-27 torx driver to get those cylinder screws. As Lake said, accessed down from top through the holes.

You can get the ring compressors for easier installation, several AS sponsers carry them such as Baileys or pick up locally. I usually just lube 'em up with a little mix oil and gently work them in with my fingers, never had a problem but then again I don't try to hurry it and I'm not doing it to make money. You can also make a compressor easy enough as some other members have done with some kind of tubing or plastic pipe.

I have the 026 manual Lake mentioned, if you want it PM me your email address. The 026 is similar enough in many ways for it to be a decent reference, if not for specifics.

Good luck, that 028 looks like it will be a fine saw when you're done.