Chainsaw Repair

Husqvarna - Stihl - Poulan - Jonsered - Dolmar chainsaws and more => Stihl => Topic started by: BlackPlague on March 27, 2018, 07:41:53 pm

Title: Stihl MS291 (2014) Rebuild
Post by: BlackPlague on March 27, 2018, 07:41:53 pm
Hey all,

I have a MS291 from 2014 that needs a new cylinder, piston and rings.

The quote for these parts from the local Stihl dealer was $465 + tax (13%) Canadian dollars.

Clearly, I won't be going that route.

The part # for the piston and rings is 1141 030 2004.

I am not sure of the part # for the cylinder. Can anybody help me out?

Is anyone aware of an aftermarket cylinder for this saw?

Thanks,
John

P.S. I've included a couple pictures of the scored P&C.
Title: Re: Stihl MS291 (2014) Rebuild
Post by: DNX800 on March 28, 2018, 05:52:02 am
The original Cylinder for your MS 291 is 1141 020 1206 and comes with piston and rings, piston pin and piston clips. (diameter 47mm) This is the newer version of the cylinder because you already have the newer updated version of the MS 291 (you say 2014 built). The change was in 2013. You can only use the newer cylinder and piston for your saw.
Title: Re: Stihl MS291 (2014) Rebuild
Post by: jmester on March 28, 2018, 06:38:38 am
So what happen to cause the failure? Lean carb setting, air leak etc.
Title: Re: Stihl MS291 (2014) Rebuild
Post by: jmester on March 28, 2018, 06:42:23 am
 @Nathaniel Vansickle
Title: Re: Stihl MS291 (2014) Rebuild
Post by: BlackPlague on March 28, 2018, 09:51:57 am
The original Cylinder for your MS 291 is 1141 020 1206 and comes with piston and rings, piston pin and piston clips. (diameter 47mm) This is the newer version of the cylinder because you already have the newer updated version of the MS 291 (you say 2014 built). The change was in 2013. You can only use the newer cylinder and piston for your saw.

Yes, you're right. This saw has the newer version.

Thanks for the part #. That's great!
Title: Re: Stihl MS291 (2014) Rebuild
Post by: Nathaniel Vansickle on March 28, 2018, 09:53:35 am
that looks like straight gas.

US list price on that cylinder is $210....not sure how much conversion fees would make it on your side plus add in shipping and customs. may or may not be worth the effort to source one from the states

not aware of AM P&C but i dont look for them
Title: Re: Stihl MS291 (2014) Rebuild
Post by: BlackPlague on March 28, 2018, 09:55:46 am
So what happen to cause the failure? Lean carb setting, air leak etc.

I'm not entirely sure. The gas/oil mix in it seems to have been good. It may have been over-revved/over-heated. Any thoughts on diagnosing cause would be appreciated.
Title: Re: Stihl MS291 (2014) Rebuild
Post by: BlackPlague on April 22, 2018, 12:11:48 pm
As a continuation of this thread, I purchased the new OEM cylinder, piston and rings and am working on the rebuild.

I'm getting ready to seal the cylinder to the pan, but when I seat the crankshaft on the pan, I can't help but notice that the oil seals don't seem to be seating nicely. The oil seals appear to be in excellent condition. If you look at the attached pictures, you can see that the oil seals are sealed to the pan on the sides (1 & 2) but not on the bottom (3). The service manual states I should not be using gasket maker on the seals.

This is my first chainsaw rebuild, so I appreciate any help. Can anybody advise if they believe this is normal or abnormal?
Title: Re: Stihl MS291 (2014) Rebuild
Post by: jmester on April 22, 2018, 08:41:39 pm
Do you have the seal down in the groove on the engine pan? It looks to me that once you install the bolts and tighten the cylinder down in will pull the seal down into the engine pan. The seal is a tight fit.
Title: Re: Stihl MS291 (2014) Rebuild
Post by: BlackPlague on April 22, 2018, 09:17:13 pm
Yeah, you're right. Once I tightened the bolts down, the oil seals closed up that gap.

I don't have a vacuum/pressure tester. Hoping there's an automotive one I can get on loan from an auto parts store.
Title: Re: Stihl MS291 (2014) Rebuild
Post by: jmester on April 23, 2018, 06:15:15 am
Here is a thread on the mighty vac that can be used for pressure and vac testing. If you hunt around on the internet you should be able to find one pretty cheap. https://chainsawrepair.createaforum.com/stickys-of-how-to-basics/pressure-testing/

Make sure you use some dirko on the engine pan and around the seals before you do final assembly also make sure you oil the piston pin and pin bearing also the piston rings and cylinder walls. I use 2stroke engine oil.
Title: Re: Stihl MS291 (2014) Rebuild
Post by: BlackPlague on April 23, 2018, 11:03:13 am
Thanks for the suggestions.

I did oil the piston, pin, bearing, rings and cylinder walls with 2 stroke engine oil, so I got that right at least.

I did not buy Dirko, but used Permatex Motoseal (https://www.napaonline.com/en/p/BK_29132).

I also did not put the gasket maker around the oil seals, as the service manual stated not to. I'm hoping I won't regret that, as you and others have suggested to go ahead and do that.
Title: Re: Stihl MS291 (2014) Rebuild
Post by: jmester on April 23, 2018, 07:35:14 pm
I think what you used will work just fine. It looks like you have the soft oil seals hopefully they will seal. Only time and a pressure and vac test will let you know. I would recommend that you do a pressure and vac test before you install the flywheel or clutch as it is easier to see the pan seal surface and the oil seals. I think you have done a good job so far.
Title: Re: Stihl MS291 (2014) Rebuild
Post by: BlackPlague on April 29, 2018, 05:42:40 pm
Just wanted to finish this thread up by saying thank you to those who took the time to respond.

I finished the rebuild today and everything seems to have gone well. Pressure and vacuum leak down tests were good, and compression was around 150psi.

Engine is idling and revving well. Chain brake working as expected and chain is getting oil.

Thanks again!
Title: Re: Stihl MS291 (2014) Rebuild
Post by: jmester on April 29, 2018, 10:53:51 pm
Glad it worked all worked and went well.