Stihl MS-460 quit running, decompression valve not popping

[Michael67]

I bought a used Stihl MS-460 chainsaw on eBay from a seller with an excellent feedback score.  Unfortunately it only ran for a few minutes before it crapped out.  The seller stated:

"HERE WE HAVE A GOOD RUNNING STIHL MS 460 CHAINSAW,LOTS OF POWER, GOOD COMPRESSION, EVERYTHING WORKS ON THIS SAW, COMES WITH A 25" BAR AND CHAIN, DOES HAVE A CRACK ON GAS TANK THAT HAS BEEN EPOXIED..."

I put the bar and chain on, filled the gas tank with fresh gasoline and Husqvarna 2-stroke oil at a mix ratio of 50:1, and filled the chain oil tank with bar and chain oil.  It did not seem to leak gas, so I tried to start it.  It took a while, but eventually it started.  It smoked a lot at first.  I cut a log in half and decided that it was working well enough to take out to cut down a tree.  I've had good results with using Sea Foam in other engines, so I put a glug of Sea Foam in the gas tank thinking that it might improve the saw's performance.

After nearly cutting half a wedge out of big dead oak the chain got sloppy, so I stopped and tightened it up.  Then as I had almost completed the second cut for a wedge it abruptly quit running.   :'(  As I walked with it over to my flatbed trailer it started smoking.  It was very hot.  I let it sit a couple of minutes, then I checked the fuel and the bar oil and those looked OK.  I checked the chain and it was OK.  I tried to start it, but it would not start and I noticed the knob for the decompression valve was not popping up as I pulled the rope.  I can move the knob up or down, but it won't pop up on its own.

I pulled the spark plug and found that it was the wrong model (NGK BPM8Y should have been NGK BPMR7A).  Looking through the spark plug hole I could see the piston move when I pulled the rope.  I borrowed a compression gauge and it read about 15psi, but I'm not sure if I got the gauge screwed in tight enough as I had to use the part on the end of the hose that normally threads into a larger part for larger spark plug holes.

Even with a spark plug screwed in snug if I hold the pull rope handle and let the saw drop it drops pretty quick, so the compression is low.  Don't know if it is just because the decompression valve is broken open or if the valve won't pop because of insignificant compression.  What should I do?  Try replacing the decompression valve?  I see those on eBay for $10.  Please advise.

Thanks,

Michael in OK  |  Stihl MS-460, Stihl MS-290, ECHO CS-305

[zackman1801]

was that 15 or 150 psi, 15 is WAY WAY LOW! if its 15 you have a serious problem! 150 is good though, pop off the muffler and have a look at your piston and cylinder walls to see what they look like.

[LorenB]

Michael,

You say that you can move the compression valve knob up and down.  If it's broken and stuck in the open position, I would think that it would feel different from a good one.  You wouldn't feel or hear the valve opening and closing. 

This should be an easy item to check.  If it's just screwed into the cylinder head as it is on my Husky, just unscrew it and see if you can blow air through it with the knob up and with the knob down.  If it passes air with the knob in both positions, you've found your problem. 

Good luck with it.
Loren

[joe_indi]

Micheal,
50:1 fuel ratio on an unknown saw was quite risky.
You never know the condition of the engine insides or the carb settings.
25:1 for a 'maiden' run would have been more suitable.
About the 'lot of smoke' you mentioned.Out here when you get that kind of smoke initially on a used saw the chances are that some wise guy has coated his cylinder and piston with grease to give the saw the needed compression to start.
Once the grease goes out as smoke, symptoms are quite similar to what you have mentioned.
BTW a couple of year ago I purchased a RayBan Ambermatic with Aviator frames  on Ebay from a seller who had a feedback score a mile long.
What I got was a cheap plastic item which is usually sold to kids on fair grounds.

I have never bought anything on Ebay after that
Joe

[rebocardo]

Do not let 30 days pass without a resolution on this "not as described" saw, if you want PayPal resolution.

If would say go to your Stihl dealership, get a valve, and retest asap.

[sawmilllawyer]

Agree with Rebocardo, let e-bay or paypal know you been ripped off. My experience with them has been much better. A couple of years ago I purchased a good used 460 Mag from someone in New York state.  Had my doubts but when it arrived it was as described. I did end up purchasing a much better and somewhat longer bar and chain than it came with, but over all it has been a good purchase. Sorry to hear about your situation.

[Michael67]

I pulled the decompression valve and it seems fine.  I pulled the muffler and it does not look so good to me, but I have no experience to go on.  You can see 13 pictures showing cylinder, piston, and rings here http://theclays.com/saw/ Feedback from someone who knows what they are looking at would be appreciated.

Thanks,

Michael in OK | Stihl MS-460 (25" B&C), Stihl MS-290 (20" B&C), ECHO CS-305 (14" B&C)

[timber tramp]

Looks pretty rough in there to me, might take it to a saw shop and have them do a compression check and/or diagnose your compression release. Don't know what saw shops are like in your area but I'd think they would do this while you wait and for a minimal fee if any.

[sawmilllawyer]

Me thinks, looks not so good in there. Can't really tell about the condition of the cylinder though. May be able to replace the piston and rings if the cylinder is not messed up. Hopefully, some of much more experienced crew will chime in.

[Red 93 L1 #3383]

Junk, It needs a top end.

[isawlogs]

Kinda hard to saye it is junk from those pics .....  :  But I do beleive that it needs work . You definitly need a piston and rings , in most cases you can hone the jug if it aint to badly damaged .
  I would be contacting the seller right quick and let him/her know of my deseption... and maybe give him 15 minutes of my time .  >:( >:(

[Reddog]

so I put a glug of Sea Foam in the gas tank thinking that it might improve the saw's performance.

I think this may have made a lean condition.
The fix is most likley a piston and rings at the least, possible a cylinder also. Have it vac and pressure tested if you change the p/c yourself. This will check for other air leaks.

[Rocky_J]

Another eBay special.  :
Sorry, but there are no deals on eBay any more. And good luck trying to get reimbursed for your junk saw.

[bandmiller2]

Mike,give the guy a chance,have him look at that top right photo.Sometimes these guys buy out a lot and don't really know the whole story.He probibly started it ran a couple of minutes and thought it OK. Frank C.

[Michael67]

Thanks to all who responded.  Saw smoked and did not run well before I put any Sea Foam in it, so the seller took it back.  Looking to replace it now, but I can't afford a new Stihl MS-460 and I don't want to buy used again.  Thinking about getting a new Dolmar pro saw....  There are places that sell them not far from where I live.

Michael in OK  |  Stihl MS-290, ECHO CS-305

[isawlogs]

Well I am glad that you got that all straitened out  8)
Both of those two saws are good saws , make your decision on the best of the two dealers that you feel comfortable working with  ;)

[sawmilllawyer]

Well, seems like there are some decent people out there,  good deal. New is best but used is one way to go if you know what your looking for. I see your from Bartelsville, what if Frank Philliphs had given up after just one bad deal? Seriously, you might check aound the reputitable saw shops in you area or down in Tulsa. Good luck with whatever you choose. Andy

[wraylow]

the sea-foam is good stuff. I put it in every saw and trimmer i tune and have been using it for years.  a cap full to a tank of 50:1 . It is a very good carbon dissolver and moisture absorbent  also boosts the power a little.