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Stihl 028 possible air leak?

Started by newhavendave, June 13, 2010, 12:21:17 AM

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newhavendave

Hello again all!  Thank you all so much for your help when I was buying this saw.  I have an 028 AV which has been running great after some tuning and new clutch springs. 

However, today after I started it up, it revved high and when I went to give it gas, it bogged down at half throttle and went to cutoff.  I checked my settings and nothing has moved.  It continued like this after a few tries before stopping.

From my experience with cars, I am thinking this is acting like a vacuum leak or air leak after the carb.  I attempted to confirm this by spraying some carb cleaner by the intake boot, but it did not seem to change the tone.  The boot also looks good, not brittle. 

One thing to note was the breather tube for the tank was brittle, cracked, and is now removed.

Thank you for any help.  I want to disassemble more but I am unsure how to proceed.

Thanks

-Dave

Al_Smith

Due to the fact that an 028 is an older saw it could possibley be a crankshaft seal .If that's the case it most likely is the clutch side seal .

Rocky_J

If the breather line was deteriorated (possibly due to ethanol) then you also want to check/replace the fuel and  impulse line as well. The impulse line is harder to see but it's the same type of line and if one is bad then chances are the other is bad as well. The impulse line runs from the bottom of the cylinder/top of the crankcase to the back of the carb. The air pressure in this line activates the diaphragm pump in the carb, so if the line is bad then the saw will not get enough fuel and sound like it's running lean.

newhavendave

Thanks guys.  I looked into it a bit further and those fuel lines seemed sturdy.  So took the carb off and dissassembled, low and behold the screen in the carb was completely gunked up.  Did a thorough cleaning and it is running like new, at the factory settings.  I wish I had cleaned the carb when I bought it!

Thanks again

-Dave

Any good mods you reccomend for this saw?  I love it.

Al_Smith

 An 028 mods just like any other Stihl . Depends on what you want it to as what to do to it .

I have an 028 farm boss in the shed to do for a trimmer when I get around to it .It's kind of whimpy as a stocker .

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