Dead 290?? Any help out there - please!

[aztoad]

Your wasting your time. That saw doesn't have enough compression to run. You'r going to have to pull the engine apart and find out what happened. You'll need rings at a minimum and I'm betting you'll find a scored piston.

Man, I love taking things apart!

Definitely worried though as this unit gets used the least of all my Stihl goodies. No problem with the 55 or 85 - and they've all shared the same gas - just that the other units are used every other week and the chainsaw usually about every 3 months or so...

 

[stihl025]

Your wasting your time. That saw doesn't have enough compression to run. You'r going to have to pull the engine apart and find out what happened. You'll need rings at a minimum and I'm betting you'll find a scored piston.

I totally agree. It doesn't matter what the saw was like the last time you used it. Somewhere along the line, the piston-scoring fairy showed up and ruined your day...

 

[aztoad]

Bought my compression tester at Harbor Freight for $10 or so (I think it was even less). Has the Schrader valve in the tip with a pressure release near the guage. Not the best or the most accurate, but it puts me in the ball park of what the saw is doing.
I have recently worked on an old 029. It only had between 110-120 psi compression cold, and it was hard to start and even harder to keep running. If yours is only reading 90-100 psi, then fuel delivery is the least of your problems. I would immediately pull the muffler and have a look at the cylinder wall and piston. Any scratches will tell the story...

From that view - it looks great - that's why I didn't start ripping it apart right away! who knows - it is a good enough excuse to take it apart.

Now to find pricing on rings and a piston too...

 

[aztoad]

How does the rope pull with the plug out?

It's a breeze to pull with the plug out - even with a bad shoulder

Remove the pull starter, and look at the flywheel/coil.

Find the magnets on the flywheel. With a pencil in the spark plug hole, rotate
the flywheel until the piston is at the top.

Now, where are the magnets located in relation to the coil?

There is a marking of N and S which appears centered on the metal portion coming out of the side of the coil.

 

[aztoad]

MS290 service manual ??

Any chance for a link to one that can help me not make too big of a mess of this?

 

[aztoad]

I totally agree. It doesn't matter what the saw was like the last time you used it. Somewhere along the line, the piston-scoring fairy showed up and ruined your day...

Now to figure out who borrowed it....

 

[treeclimber jul]

If there is a schrader valve on the end of the compression hose, (the end that goes in the saw) make SURE that it's not loose, I bought two differant brands and each one was loose so I would not get a good reading.

Hope this helps

 

[aztoad]

If there is a schrader valve on the end of the compression hose, (the end that goes in the saw) make SURE that it's not loose, I bought two differant brands and each one was loose so I would not get a good reading.

Hope this helps

Just checked to make sure - didn't check the rental unit before I returned it but the new unit is great. It actually comes with extra valves, a little tool to replace them and several different adapters. Can you tell I like tools.....

Anyhow - no such luck - can't blame it on the valve...

 

[stihl025]

Any chance for a link to one that can help me not make too big of a mess of this?

PM me your email address

 

[aztoad]

Thanks to all for all the help - but here is the latest...

OK, thanks to Little League tournaments (that is field setup and administration stuff) removing any extra breathing time, this weekend we took a break so I finally have a few minutes to have some fun...

I have it torn down. The rings wouldn't require a ring compressor if I wanted to put it back in because they appear to be glued into the grooves!

Seems like a pretty obvious issue that would definitely cause a lack of compression but wondering two things - first what probably caused it and second how the ???? do I get the rings out now without damaging the piston!

Basically think the reason for low compression is that the rings are stuck deep in the piston grooves! Doesn't appear to have any scoring and what little carbon deposits came off pretty easily - even with just a paper towel!

Have it soaking right now in gas to hopefully loosen up the deposits but WOW!

and of course the follow-up - heard locally that rings are about $13 a piece - is that reasonable? For the piston and rings I'd be looking at $150??

Do those figures sound right or should I be considering aftermarket? Or is that a 4 letter word?

Thanks

 

[aztoad]

another thing I forgot to ask...

In addition to the above mentioned issues...

Baileys for rings? Seems like a good price - anyone have good / bad experience?

Dirko HT - if I can't find it around here - any suggestions where to order or is there a superior product I should use to seal the head back on?

Thanks

 

[aztoad]

Piston pricing?

Unless someone has some good advice on how to get these rings off - I am definitely at a loss. There is no scoring, no burning - and only about 100 on the compression...

I saw that rings can sometimes go immobile if some of the piston "melts" into the grooves. If that is true can I use a torch to reheat and remove the existing rings?

With the exception of the rings not being mobile - the piston really looks like new.

 

[Lakeside53]

Just bust them out... but... if the old rings are real tight, the new rings won't be any looser.. so you need to adress that. It's likely you have carbon packed in behind the rings. Use an old ring to carefully scrape that out. Don't damage the walls.

Any Stihl dealer can sell you Dirko, but the tube has enough in it for about 500 rebuilds!

 

[aztoad]

Just bust them out... but... if the old rings are real tight, the new rings won't be any looser.. so you need to adress that. It's likely you have carbon packed in behind the rings. Use an old ring to carefully scrape that out. Don't damage the walls.

Any Stihl dealer can sell you Dirko, but the tube has enough in it for about 500 rebuilds!

As for the busting them out...I don't think I have anything in my arsenal that would safely pry - push - or remove these things. The compression was low because these rings are the same diameter as the piston - maybe even less!

I'm going to get some pictures of it to post (if I can figure out how to get them uploaded) as both the rings and piston appear to be in great shape - just that the rings are buried in the grooves!

Let me guess - rings ~ $26 - piston ~ $130 - Dirko - priceless! Any idea how much that will run? Is Dirko the best and does anyone sell small containers?

Thanks

 

[aztoad]

Pistures of pistons

Here are a couple...I have not done anything other than soak it in gas and clean it off with a papertowel...

 

[belgian]

You will probably have to order new rings as it's quite difficult sometimes to get them out intact.
here's a link to a forum where this identical problem was discussed
********************************/phpbb3/viewtopic.php?f=9&t=6173

 

[aztoad]

You will probably have to order new rings as it's quite difficult sometimes to get them out intact.
here's a link to a forum where this identical problem was discussed
********************************/phpbb3/viewtopic.php?f=9&t=6173

I'll leave these set in the gas overnight and try again tomorrow - Thanks...

Seems like the heating / cooling / lubricating / penetrating oil may work too...

 

[Taxmantoo]

I'll leave these set in the gas overnight and try again tomorrow - Thanks...

Seems like the heating / cooling / lubricating / penetrating oil may work too...

Might help to have a pair of ring expanding pliers.
These are very nice.

These are very affordable, and you can get them just about anywhere, including the Snap-On truck.

 

[aztoad]

Might help to have a pair of ring expanding pliers.
These are very nice.

These are very affordable, and you can get them just about anywhere, including the Snap-On truck.

Appreciate the suggestion. I do have a set from about 20 years ago that are great for getting the rings on (and sometimes off) when everything moves and you can get a tool into the ring. Are these different? Look very similar but the ones I have can't even begin to budge these things - yet...

Unfortunately - these puppies are stuck but good! Trying the torch now...they've soaked all night...

 

[Taxmantoo]

OK, I didn't know you already had a ring expander on hand.

Ammonia can free steel parts that are corrosion welded to aluminum parts by dissolving the corroded aluminum (and then it will dissolve the aluminum if you leave it soaking too long).