New chainsaw abused by dealer: Is it possible to know if damage was done?

[zoltar]

I recently bought a new saw (Stihl MS-261 C-M) and it was first started by a dealer. He forgot to disable the chain brake and revved the saw a few times with the brake engaged before I got him to disable the brake. After disabling the chain brake, he let the saw run at WOT (no load) for about 15 seconds. It was really hot at that point, I noticed a little bit of smoke coming from the muffler, probably because some chain oil had spilled on it.

I did some googling before I posted this, and I've found several threads where people shared similar experiences, but none of them was able to answer the main question I have: How would I know if any damage was done to the saw because of this abuse? Would it be immediately noticeable? I used the saw to cut some wood around 30 minutes after I got home from the dealer, and it was working fine as far as I could tell.

[Maine logger88]

That would have done no damage pro saws are very tough. You can pull off the clutch drum and see if it has any heat discoloration. I've had saws that the clutches got really hot like smoke rolling out of them and they never bothered. As far as holding wide open that won't hurt them either when the 562 was first introduced I guess it was recommended that they be held wide open in wood for 5 minutes...

[zoltar]

Thanks for the reply. Here's what the clutch drum looks like on the outside:


Looks like new (to my untrained eyes), so I assume I don't need to bother with taking it off to inspect further?

[Ianab]

It will be fine. It takes more abuse than that to damage a saw. Smoke off the muffler is likely just anti-rust coating from the factory burning off the first time it got hot.

[Maine logger88]

Looks new to me too zoltar! Welcome to the forum btw! As a full time logger my saws get used fairly hard I try to take care of them the best I can but the definitely have a rough life. But anyway my point is the pro grade saws like your 261 are very very tough it's amazing to see what they can do and go through and keep running like a charm! Biggest thing is good gas and oil keep the air filter clean and they will do a lot of work!

[zoltar]

Thanks for the reassuring feedback guys! On the bright side, at least I know the chain brake is working now. I was a bit concerned about overheating, especially because the saw was set to winter operation, and the dealer ran the saw inside the building. The room temperature was certainly below 20 C/68 F though, and as I've already said, it wasn't running for very long, so I guess it's all good.

I just have one more general question regarding engine break in before I put this to rest: I've been interested in this subject long before I got this chainsaw, because it is relevant to anything with a gasoline engine and I've found no conclusive answers. My understanding is that the only purpose of the break in period for any gasoline engine is to get a good seal between the piston and the cylinder wall. If that's correct, it seems that a simple compression test would be sufficient to test the effectiveness of the break in method that was used. Good compression after the break in period means the engine is performing at 100% (assuming nothing else is wrong), and whatever you did during the break in period was good enough, or am I missing something?

Sorry if this question is too general for a chainsaw forum, I'm just curious and I'm throwing it out there in case someone here happens to know the answer.  ;)

[Maine logger88]

Actually that is what the clp class we took taught us to do to check the chain brake! You are correct on the break in! With saws I have always just put them to work like I would any other day ( not saying everything I do is right) some of them seem to break in gradual and some it's a notable difference after a few tanks. I also work part time in my uncles diesel shop after work or during slow times there are verious different methods recommended. The one that makes the most sense to me is make sure you have good oil pressure and the engine is running smoothly then idle it up a little not staying at the same rpm for to long but not Changing too quickly either then get a load on it and take it for a road test by the time you get back it should be broke in. That's about all I know about break in. I suppose you could do a before and after compression test that would be interesting!

[zoltar]

I suppose you could do a before and after compression test that would be interesting!

My saw is still on its first tank of gas, so hopefully that will be early enough in the break in period to show some difference. To get a good comparison, I'm sure it would be best to have the saw at the same temperature for both the before and after measurements. Does it make sense to measure the pressure on a cold (room temperature) saw, or should I let it run for a while before I do it?

[Mad Professor]

Sounds like your stihl dealer has an azz for a salesman.  I hope the service/parts people are not one in the same.

I don't think what the jackazz did hurt the saw, but if he wanted to use one of my saws I'd give him a wild thingy with a gal of mix.

[old guy]

Many of these new saws are taking 10 to 12 tanks of gas before they reach their full potential. Just run it hard & don't worry about the break in.

[Maine logger88]

I would think measuring cold would probably be more consistent

[ZeroJunk]

If that would hurt a saw they would all be flying to pieces.

[thecfarm]

Get that saw into the wood.  ;D  That's what it's made for. I don't see how that saw was hurt. Mix your gas the way you should,wear the correct safty gear and you are all set.

[zoltar]

I suppose you could do a before and after compression test that would be interesting!

I'm just about ready to measure the compression, and I will post another measurement after about 10 tanks of gas to see what difference the break in phase makes. Before doing that, I took some pictures of the piston and cylinder, covering all postions. I thought this would be nice to compare along with the compression numbers. The piston looks fine to me in all of the pictures, but I was a bit unsure about the pictures that show the top of the piston. It was just oil or something, though. I could remove that stuff with a cotton swab.

[Greenerpastures]

Hi, your saw looks fine, there is no discolouraiton on
the clutch drum, so no real heat to do any damage.
The smoke would have also been from the lube used
to assemble the saw, and more so from the,chain oil,
which plasters that area and would have smoked
because of the bit of heat in the clutch drum.

The rings going round the piston are normal, they hold
a certain amount of oil to keep the piston lubed.

If I were you I would keep the muffler on, so no small
dust particles get blown in there.

Nice saws, I just bought an MS 362.

[zoltar]

If I were you I would keep the muffler on, so no small dust particles get blown in there.

I wasn't going to use the saw without the muffler, I just removed it to take some pictures of the piston, for later comparison. A few dust particles and a tiny bit of cotton lint almost certainly got in while I was poking around, but I assumed that would make no difference. After all, no one thinks twice about removing the spark plug, and it seems like it would be even easier for dust to get in the cylinder that way.

[Greenerpastures]

Hi, I understand you were not going to run the saw with no muffler.
I open my saws when something goes wrong, have not had to
open one yet, or to clean them. It only takes one careless mistake
by someone to mess up the inside of an engine.

I clean around the pulg with airline before removing plug, so no dust
gets in.

Have you used the Saw yet. I had mine out this morning, and am growing
fond of it.
Going to post regarding air filtration on these saws, to find what precautions
I need to put in place, heard the came with different filters, and some people
were not pleased with dust getting through.

Regards, john

[zoltar]

I open my saws when something goes wrong, have not had to
open one yet, or to clean them. It only takes one careless mistake
by someone to mess up the inside of an engine.

Sure, but I had heard that you should open them up at the beginning of every season to remove carbon deposits. Don the Small Engine Doctor is one of the guys recommending this on his YouTube channel. Check out 4:35 in this video:
https://www.youtube.com/watch?v=5LJpW3nZwqg&t=272s.

If you wait until the saw doesn't work properly, it seems to me that you run a much higher risk of causing permanent damage. What kind of mistake would I have to make to damage it by inspecting the piston and exhaust port? Unless I did something really stupid, like spilling a cup of hot chocolate in there or something, I don't see how I could mess it up.  ;D The only warning I've seen (both the manual and forum/youtube advice), is that if you're scraping away carbon, make sure the piston closes the opening completely so that chunks of carbon don't fall into the cylinder.

My saw being almost new, it was of course not necessary to open it up, but I was curious to see what the piston would look like. I've been curious about the break in myths of engines since bought my first outboard, but they are not nearly as accessible as my chainsaw, so now I can't help myself, I have to experiment with it.  ;) This time, I intend to find out exactly what happens. I will not do anything special to break in my engine - will use it normally from day 1. After about 10 tanks of gas, I will do another pressure test, and take new pictures of the piston. Then, the next time someone asks how to break in their chainsaw or whatever, I should be able to back up my recommendation with data. Hopefully it will be a recommendation, and not a warning on what not to do. ;D

[DelawhereJoe]

Most of the time the carbon deposits are the result of the saw running rich or too much oil in the mix, your c-m model isn't going to be on the rich side of things. If you over oil your mix you can have other issues over time.

[ZeroJunk]

If you have fun messing around with it is the main thing.

[ladylake]

Most of the time the carbon deposits are the result of the saw running rich or too much oil in the mix, your c-m model isn't going to be on the rich side of things. If you over oil your mix you can have other issues over time.

Or leaving them idle too long.   Steve

[Greenerpastures]

I open my saws when something goes wrong, have not had to
open one yet, or to clean them. It only takes one careless mistake
by someone to mess up the inside of an engine.

Sure, but I had heard that you should open them up at the beginning of every season to remove carbon deposits. Don the Small Engine Doctor is one of the guys recommending this on his YouTube channel. Check out 4:35 in this video:
https://www.youtube.com/watch?v=5LJpW3nZwqg&t=272s.

If you wait until the saw doesn't work properly, it seems to me that you run a much higher risk of causing permanent damage. What kind of mistake would I have to make to damage it by inspecting the piston and exhaust port? Unless I did something really stupid, like spilling a cup of hot chocolate in there or something, I don't see how I could mess it up.  ;D The only warning I've seen (both the manual and forum/youtube advice), is that if you're scraping away carbon, make sure the piston closes the opening completely so that chunks of carbon don't fall into the cylinder.

My saw being almost new, it was of course not necessary to open it up, but I was curious to see what the piston would look like. I've been curious about the break in myths of engines since bought my first outboard, but they are not nearly as accessible as my chainsaw, so now I can't help myself, I have to experiment with it.  ;) This time, I intend to find out exactly what happens. I will not do anything special to break in my engine - will use it normally from day 1. After about 10 tanks of gas, I will do another pressure test, and take new pictures of the piston. Then, the next time someone asks how to break in their chainsaw or whatever, I should be able to back up my recommendation with data. Hopefully it will be a recommendation, and not a warning on what not to do. ;D

We have a 40 year old Stihl 041AV, never ever opened,
it still runs.
Not everyone can get oil mix and tuning right.

I just wonder what these Mtronic saws will look
like when they are opened, and where they will
be in 40 years time.

We could ensure plenty of fuel went into our old
non MT or AT saws, and that keeps them clean,
unless you over do it.
Too much oil in the mix will cause trouble, oil does not
burn clean like the gas/petrol content of the mix.

Its all in the tuning.

Regarding what could destroy the saw, how about someone
opening a door in a gust, and dust sitting around the saw
gets blown in there, ive seen it happen, simple thing,
Ive also seen dust falling of rags, the sleeves of boiler suit,
jumpers, hats, hair etc, and landing on bearing surfaces,
I just happen to have extreemely good vision, others standing there
did not see what I did, but a crankshaft that looked like it was roled
around in barbed wire opened their eyes whe they had to cut
it again and put in new bearings.

Regarding taking carbon off the port, I would have the piston down,
not closing the port.
Why, well its not the big bits that are going to get away on you,
its the smallest pieces of carbon that are going to get trapped
between the piston and cylinder, and completely destroy it.

It is much easier to order a new gasket and take the barell off
if tou need to clean carbon or gunk from the ports.
Or keep the piston ring just levell with the bottom of the port,
and use a hoover as you loosen carbon or gunge with something
made of plastic, not steel, this way all that destructive dust can
be sucked out.

[zoltar]

Sounds like a small engine mechanic's workshop needs to look like this: