stihl over heating cutting out

[BTS]

i have stihl 039, thats used for bits and bobs round yard, it starts fires up revs well then cuts out after about 4mins and seems very hot, any ideas what could be wrong,

i have checked, fuel and air filters, piston and pot and carb settings and all seem as they should be, fuel is fresh and mixed correctly, muffler is clear.

[Graham]

Had an 026 that did that. After much stripping looking for cracked wires, perished manifold etc turned out to be the carb. It had been stripped and cleaned a few times before it eventually decided to go. The second carb kit did it. Even the dealer had given up on it.

 

Could possibly be crank seals leaking as it warms up hence it getting hot from running weak as they allow air in.

[spudulike]

If the piston is ok and compression is fine then check the fuel tank breather and the gauze filter in the carb, it may have a bit of muck in it - favourite is a semi blocked breather - try loosening the fuel tank filler cap and see if it cures the problem, if it does then it will be the breather.

 

It could be low on compression - a warm engine lowers compression to the point it won't run. The coil could be on the turn or ot may just be running a tad weak on the L setting.

 

If you get stuck - sent it over!

[Big Bolt]

I had a chap whom worked for me started to have proplems with his saw over heating , i use sticky old bio oil in the saw's and he was a bit messy tiping it in and used to spill some on the fins , this over time with crap build up and none cleaning stopped the air flow causing it to over heat and sieze up , tried to get a rebuild out of me sorry m8 your saw your proplem

[spudulike]

Had that on a MS200 that I purchased as a non runner - cleaned it up and it ran perfectly after a strip, clean and rebuild.

 

It is the free present from ebay saws - 3 mugs full of oil and fine chippings - nice........unless you buy from me:thumbup:

[BTS]

well completely stripped down everything looked ok then noticed previous owner has put piston in pot wrong way round missed it first time well swapped round got rid of masses of sealant fired up and saw was good as new,

[spudulike]

You are lucky the ring ends didn't snag in the exhaust port.....very lucky!

[BTS]

i missed it first look but glad spotted it could have be costly

[spudulike]

For future reference, if you clean the carbon off the crown of the piston, the arrow points toward the exhaust port!

Generally the ring ends either slide down either side of the inlet port or the piston ring ends don't come lower than the top of the inlet port.

[testcricket01]

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