028 stihl runs hot

[sugarbush]

i have 2 028's and both do the same thing. start good and run good until i cut with them, then start to run hot. pressure checked both to 8# and holds pressure ok. carb. and gas line the same. pulled mufflers to check for scoring and looks like new. any help would be appreciated. i'm new to posting but have been an avid follower of many. i'm retired and my hobby is repairing chainsaws. very impressed by those of you willing to help us that are not near as knowledgeable. brian.

 

[Kenskip1]

Runs hot

Sugerbush, The first thing I would check is the cooling fins on the cylinder. If the fins are built up with saw dust wood chips this may be causing your problem. Second is a lean mixture.The air opening near the recoil may be partially blocked. Was this saw used in cold weather? If so it may have some type of air diverter to use hot air from the cylinder. Finally, are you using a fresh mix? Ken

 

[Crofter]

Assuming you have cleaned the fins well of built up sawdust and the air cleaner is clean. How long of bars are you running and what is your cutting style. I dont mean it as an insult but I wonder if you could be lugging them down to where the fan doesnt do its best cooling job.

 

[timberwolf]

Muffler screens clean?

 

[sugarbush]

028 stihl running hot

both saws have been cleaned and airpresure used. saws are run in 30 to 50 degree temps. they have fresh gas, 40/1 mix with ecko oil. the bars are 16". the exhaust clean and no screen. could it be timing? brian.

 

[Kenskip1]

Running Hot

Sugarbush, When you say that the saw runs hot, what sort of inddication are you judging this from?I do not mean to insult you but with out more specific information this could be hard to remedy.When you shut it off does it smell as if something is burning? After a hard cut do you let the saw idle for a few minutes to help dissapate the heat generated? Stinl recommends (Quote from my 028 owners manual,{After a long period of working at a full load it is advisable not to shut off the engine immediatly, but let run for a short while at idling speed. This allows the heat generated in the engine during full throttle operation to be dissipated by the flow of cooling air aand also engine-mounted components(ignition,carburator) from thermal overload} This is from page 26 in my owners mannual
As to your queary on ignition timing, I doubt if both saws would have the same problem. What type of gas are you using? If 87 octane or less I suggest going to the highest in your area. I hope this will help, Ken

 

[sugarbush]

ken, thanks for advice, gas is 92 octane. if i make about 5 cuts in a 12" oak it will smell hot and if you spit on engine or drop snow on it, it boils . if i continue to cut it will want to die when dropping down to idle. i thank every one for there input. brian.

 

[Kenskip1]

Run Hot.

Put in A NEW GAS filter!!! Check gas lines for kinks. By the way, just because moisture fizzles on the engine does not necessarly mean that it is running hot. Ken

 

[West Texas]

I've had this happen on several saws; and, it has either needed more clockwise on the LA idle adjustment or its been the needle lever needing adjustment in the carb. At least twice or more it was the needle lever needing adjustment. Tom

 

[sugarbush]

028 stihl running hot

ken, i don't think it's a gas problem, that's been checked. it's definately giting hot to the point if i keep running it that it will seize. i think the piston is expanding with heat. unless the 028 is prone to vapor lock and that is making it run lean, then gitting hot. both of my 028's doing the same thing. i'm rambling on but i've tried everything including pressure and vacum check. gas line, commpression 150# on one saw and 135# on the other. i believe there may be a common problem with 028's. still looking for solution. thanks to all of you for input , don't quit now. brian.

 

[Kenskip1]

Running Hot

Brian, I bought my 028 new back in 1985. I have cut wood in July in upstate NY in 90+ temperatures,also in August. I hope that you will have more success with others doing the posting. By the way, my 028 has never vapor locked.As to your timing queary, the timing (on my saw) is fixed from the factory. I suspect a lean mixture in your carb. keep us posted, Ken

 

[davefr]

Do a vacuum test. A pressure test alone can't rule out a leak. Sometimes the crankcase is able to hold pressure but unable to hold vacuum due to leaky seals.

How's your intake boot and pulse line? Are you sure the fuel line is OK?

It sure sounds like you're seeing the early symptons of lean seaze.

 

[skwerl]

I'm gonna go out on a limb here and suggest that it's running lean.

 

[stihltech]

vent

Check the vent, clean the vent or replace the vent.

It could be the vent.

 

[sugarbush]

028 stihl running lean

davefr, i vacuum checked both saws twice as my tester pumps pressure one way and vacuum the other way.( sliding the knurled ring one way and then back.) wouldn't intake boot and pulse line be checked in that process? stihltec, i think i checked gas vent but will check again. thank you all, i'll post what i find tomorrow. brian.

 

[Lakeside53]

Retune the carb to Standard settings. Ignore "performance". See if it runs hot.

 

[sugarbush]

028 stihl running hot

lakeside, set both jets at one turn and still runs hot but smokes at idle. clears up at three quarters open on low jet. also put on new vent hose and cleaned screw. i also pressure/ vacuume checked again and no leaks. i'm stumped. is it possable enough coating gone off cylinder to cause over heating? i'm searching. thanks, brian.

 

[Kenskip1]

Running Hot

Brian, Lets go to plan B! Are you able to get this thing to 4 stroke or does it just scream? Lets try this.Start the saw and let it idle.Give a few revs just to warm it up. Now carefully open the low mixture screw (closest to the cylinder) counter clockwise until the engine starts to slow down. Does it slow down? If so slowly return the screw back to it's origional position. Accelerate the saw. If no hesitation is presant you are in the ball park. If it wants to die open the screw an additional 1/8th of a turn. Now to the high speed of the spectrum. Open the high speed needle a half turn.Find a piece of wood and make several cuts. As of now the saw should be running extra rich. If the engine goes back to screaming you have a fuel blockage. If it will not race, (this is a good sign) then you will have to slowly return the High speed screw to its origional position.It could be your metering valve in the carb is not letting enough gas into the carb as the engine requires it, causing a lean mixture verifing the hot saw. Litterally! A week diaphram may not be pulling enough gas from the tank. Either way a carb kit sounds like a good investmant. My 028 (1985) is as reliable as high gas prices and high taxes! I hope this will help, Ken

 

[sugarbush]

028 stihl running hot

rebuilt carb this morning and it no longer runs hot. thank you for input. i should have tried that earlier. a lesson learned. brian.

 

[Kenskip1]

Running Hot

Brian, We are never two old to learn something new! Ken