Stihl 029 Farm Boss issues

The saw is 17 years old and the only repair I had done is repair of the choke mechanism. So it has served me well until recently. The last few times I used it, it ran fine until I shut it down for a break or to refill gas/oil. It would not restart unless I let it sit for quite a long time. Then ran fine until shutdown again. Took it to Stihl dealer and was told the piston was scored and repair would be $280 - $350 depending on cylinder condition. Bought a replacement saw instead. But, would this really cause the issue I was experiencing? I kept the old saw and am trying to rebuild it myself. I opened the crankcase and pulled the piston. Aside from carbon on the top of the piston, it looks fine to my untrained eyes. Same with cylinder. Where else should I look for problems? It was a pain to tear down so, as long as it is apart, what all would you recommend be replaced.

 

If you don't have piston/cylinder problems I would still use new rings and reassemble. For an old saw you might want to check out the fuel line and fuel filter. Those bits tend to deteriorate over time. Another possible weak spot with age is any rubber items like the connection between the carb and the inlet port. It doesn't take much of an air leak/crack to make the engine run like sh!t.

 

Did you ever pull the spark plug out when it would not start to see if it was getting any gas. Could have been flooding out.

The dealer sounds like they were spittin in the wind. So all the piston skirt surface looks good with no vertical marks on it.

 

Welcome to the club, mtkeg.
I think your gonna like it here.
Help is on the way

 

To the OP, hello you will like it here....You will also have twice as many saws as you do now excactly a year after joining this site LOL....

There are a lot of knowledgeable chainsaw guys on this site.... As a matter of fact Mastermech is one of them!!!!

 

Thanks for the responses. Pics are attached. Replaced with another Farm Boss - MS271. Qualification - I just retired and never messed with small engines prior to about a month ago when I decided to mess with my tiller. Rebuilt the carb and it now purrs. So, no I didn't try to diagnose the issue outside of cleaning the air filter. Just took it to the dealer.

So, what is your opinion? Is the piston toast?

 

That piston looks to be in great shape. I would put some new rings on it and some new crank seals since you have it apart. By what the piston looks like I assuming the cylinder looks good also.

You could still have a carb problem but will not know until you get it back together.

 

I agree that piston looks good. Could be an air leak somewhere else. Intake boot, seals, bearings, impulse line, etc. Or more likely it could be a carb issue.

It may be time to pick a different dealer though. At the minimum they misdiagnosed your problem. Worst case scenario they purposely jacked up the repair price to sell you a new saw. I've seen this happen before with friends and family.

 

OK. I pulled the paperwork on the old saw and I guess I mis-stated the dealer diagnosis. Sorry about that. They reported " intake manifold was leaking causing lean running conditions. Scored wall. Could possibly hone cylinder but best bet is to replace it." I'd swear they said piston over the phone.

It's hard to get a good pic of the cylinder but there are some vertical lines at the top of the exhraust side of the cylinder. it feels smooth when I run my finger across it though.

 

I agree with that the piston will work for sure, as stated new rings and seals....

 

So, fuel line/filter + rings+ seals. How about the intake manifold which dealer kind of implied as the problem? Inspection reveals no cracks/holes. Or carb which some feel might be contributing. Do you recommend OEM parts or are after market OK?

 

Just from the looks of the piston I doubt that the cylinder has any serious damage to it. Like MasterMech said do not be afraid to use some fine grade sandpaper or scotchbrite to smooth out the cylinder wall.

The fact that you cannot feel the vertical lines on the cylinder with your finger tells me there is nothing wrong with the cylinder.

If the lines were deep above the exhaust port you would have lost some compression and that does not sound like the case to me.

Like BarcroftB said time to look for another dealer.

 

Thanks again. Any opinions on OEM vs. after market?

 

What's your goal with fixing the saw? Back up saw? Fix it and sell it?

 

Backup saw.

 

Guys have had some luck with aftermarket stuff. For a back up saw I don't see any reason why not.

 

I would keep the cylinder and piston you have it will work just fine and still provide years of service for you.

New rings, crank seals, fuel lines, intake boot. That is what goes bad.

 

Got the parts ordered. I'll post back with the results of my rebuild when I get this put back together again. Thanks again for the input.