Chainsaw..strange problem

[Kai Thomsen 17]

A friend of mine came by yesterday and asked if i could repair his chainsaw for him.

This little thing,  a Husqvarna 136  is really wierd..

 

When i tried to start it it took forever to get it going, i checked the hi/lo needle and after a little adjusting i managed to get it to idle but at the slightest throttle it would flood and stall.

Pulled the carb and replaced both diaphragms =  it starts ok and idles..well sort of ok,  wont idle real low no matter how i adjust the Lo needle  but still floods if i pull the throttle... if i nurse it up to speed i will run ok at full throttle ?

turns out that the tip on the Lo needle is broken and is stuck inside the carb.

 

I gave up and replaced the carb with one i know is ok, and put new gaskets and diaphragm in there as well.

 

Now it starts fine at 2-3 pulls, it still runs best if idle is set a little high, but now comes the wierd part..
Holding the saw as you would when cutting up wood, it runs reasonably well, it still likes to idle high but revs up with no hesitation and for its small size has plenty of power.. But..

 

Tilt the saw to the left as in "pullstart side downwards" and it slowly floods and sputters to a halt.  I need to hold the throttle wide open and pull several times to get it started again. It does the same every time.

Tried 2 other carbs..one from a strong running husqvarna 142 but still i get the same problem.

What the (beep)  is going on ?

 

I have one theory left..  but maybe i'm looking at the wrong place:   One of the crankshaft seals is leaking ?  so when i hold the saw in normal position i can adjust the carb sort of "ok",  but when i tilt the saw the seals is no longer leaking (or not as much) and the carb settings is now on the rich side.


Anyone with a good hint ?
 

 

 

[Anglo Traction 761]

Kai, I'm inclined to agree that you can rule out the Carb issue now that you've changed them out. You have adjusted the Carb to account for a possible In-Leak to the Crankcase via the Seals.

 

I believe the Seals are in the Bearings?. If so , it may be that the Bearings are loose in their Crankcase mounts, as there should not be very much lateral float of the Crank.

 

It may be worth checking the 4 bolts and the Gasket that hold the 2 sections of the Crankcase together, as they hold the bearings securely.

 

If any air is being drawn in there, it will definately screw up your Fuel mixtures..........................Bye the way, I'm no expert.

Regards      

[chrisd200(inactive) 56]

NO expert here either, but I was Husqy dealer a few years back. The most common prob was the carb (you have covered that) I am assuming you have checked/replaced the fuel lines and filter. A bad crankshaft seal can cause a saw to do strange things like not idling and reving too high, carb seems to need constant adjustment etc. They were also bad about developing air leaks around the intake boot. Not sure what style intake the 136 is using but that was a very common problem with the larger 359. Good luck!

[CRE1992 135]

Well being I like chainsaws, it sounds like it is a crank case seal... If it was an intake boot it would do it all of the time...

[chrisd200(inactive) 56]

Well being I like chainsaws, it sounds like it is a crank case seal... If it was an intake boot it would do it all of the time...

yes I agree it does sound like a crank seal, but my buddy and i both had the 359 husqy which were notorious for intake boot leaks and they would start acting up after the saw warmed up a little, much like a crankshaft seal.

[oldredrider 2,553]

As chrisd200 said, check the fuel pick up and filter. I had one (Husky 36) act like yours and the fuel line was rotted out at the filter/pickup. Seemed like flooding out but was fuel starved, Good luck.

[Kai Thomsen 17]

Tore it apart  yesterday, the tiny spring that is in the seal (on the seal lip ?)  was broken in the right side behind the clutch/oilpump. Bearings looked fine so i just put two new seals in there and assembled everything again with a slight coat of gasket sealant where needed. 
Adjusted gap between ignition coil and flywheel, put a new sparkplug in as well. 

 

It fired right up at second pull and after a little adjusting on the LO needle screw  ( 1/4 turn IN ) and Idle screw it seems to run ok now

[Anglo Traction 761]

Weel done Kai, Good news for your friend  ........... Bad news for trees