Chainsaw Repair

Husqvarna - Stihl - Poulan - Jonsered - Dolmar chainsaws and more => Husqvarna => Topic started by: phil1863 on May 25, 2017, 08:32:02 am

Title: husqvarna 445 wont start
Post by: phil1863 on May 25, 2017, 08:32:02 am
the husqvarna 445 is 3 years old.  Its rarely used...probably between 10-15 days use since I have had it. The  last winter I did not drain the fuel.  So far this summer I have used it about four times.  It was working fine.  The last time I used it, I ran out of fuel(tank empty) twice. It was working fine(although I did notice that it was not idling quite as smoothly as it had been earlier). Anyway I refueled it once more and went to start the saw, but it did not wont to know. It was totally dead. I am a novice at these things, but I tried the following.

1. I changed the plug.  In fact I tried two other plugs that I had...ok they were not new.  I have ordered some new plugs and will try one of those as soon as I get them.  However if I lay the plug on the cylinder and pull the rope I do see a spark.  But my first question is, how bright should this spark be?  I can see it clearly insdie a darkened that good enough or should I be able to see it in near daylight?

2. I had a google and it was suggested that I try some carb cleaner in the spark plug hole and see if it would fire.  I was unsure as to if I should try this with or without choke.  I tried both and neither would fire.  I also tried a tiny amount of fuel in the spark plug hole.  No joy at all. As far as I can tell the compression seems fine (putting my thumb over the plug hole) and I would be surprised if its a compression problrm.  Should it have fired if I had done the above or is this a techneque that does not work for chainsaws?

3. Another suggestion is to remove the fuel adjusting  screws (sorry forgotten there correct name) and spray some carb cleaner into the holes  After I have tried the new plugs (which I do not think will make any difference), it may be that I will try this.  I dont wont to start unscrewing things until I have exausted any other options,

I would love to be able to fix this myself, and would much appreciate any comments on the above or maybe some other suggestions as to something I could try.  It is just odd how it was working fine before running out of fuel and then just would not start?

Thanks, any suggestions welcome.
Title: Re: husqvarna 445 wont start
Post by: Cut4fun . on May 25, 2017, 12:47:34 pm
You say you got spark and that sounds good.  My WAG is flooded first.
I would pull plug leave out and pull over to remove any flooded fuel just in case.  Then let set for 24hrs. 
Dump mix from tank. Check fuel line and fuel filter.
Pull and check air filter, leave off.
Pull muffler check for any scoring. I have made the mistake twice now on ones that feel good on psi and wasted alot of my time messing around.

After 24hrs, Put good plug back in after checking  gap.  Fill with good new mix.   Try it and see what happens on your cold start.  If nothing pull plug and see if it got fuel aka wet.
Title: Re: husqvarna 445 wont start
Post by: farmboy on May 25, 2017, 10:50:21 pm
Agree w/pull muffler check piston for scoring.  You can not go by feels like it has good compression.  I've been fooled more than once.  If not running and I have spark 1st thing I do is check comp w/comp gauge.  Do it routinely now.
Title: Re: husqvarna 445 wont start
Post by: phil1863 on May 27, 2017, 07:26:31 am
Thank you so much cut4fun and farmboy for your help.  I did try a new plug and as I expected it did not make any difference.  I am a bit of a novice here, but I dont think that it was originally flooded.  I assume that the spark plug would be very wet for it to be fact I originally thought that this must be fuel starvation because the plug seemed to be somewhat dry.  However having read somewhere else that a little blast of carb cleaner into the plug should make it fire I was a bit confused when it did'nt fire, so was it fuel starvation or something else. Maybe this technique of carb cleaner does not work with husky chain saws?   I will take the plug out and leave for 24 hours to see if that helps.  I will dump the mix as you suggest,  To be perfectly honest when I did the oil/fuel mix I did have a bit of trouble in that maybe I mixed to much oil with the fuel...I am going to get a better mixing tool then the one I have got. I did not think that the mix was that bad to make a difference, but maybe I am wrong again.  This saw has a fuel primer on it.  The bubble is full.  The air filter looks perfect, but I will give it a wash.
I will try and check how much on ebay a comp w/comp gauge is.  It sounds like that could ve very useful. Failing that i will remove the muffler and check the pistons.

I will follow your instructions and get a better mixer and a comp tester and see where that takes me.

Thank you so much for your help!!!!
Title: Re: husqvarna 445 wont start
Post by: Cut4fun . on May 27, 2017, 10:12:36 am
I only use mix in a squirt bottle for spraying through carb or plug hole.  Never heard of anyone using carb cleaner to try and fire one off. IMO put some mix in a squirt bottle ( like the oil cans with squirt handle and long nozzel )
Title: Re: husqvarna 445 wont start
Post by: 3000 FPS on May 30, 2017, 11:43:24 am
Yep that is what I do too.    I hold the throttle wide open and squirt a little bit of fuel mix into the carb.  Start pulling until it tries to start.   
If it does not start or try to start then pull the plug and if it is wet then the problem is either no spark or low compression.
Title: Re: husqvarna 445 wont start
Post by: farmboy on May 30, 2017, 10:38:20 pm
+3 on the mix in a squirt bottle.  To the OP take the muffler off and look at the piston it's only 2 screws.
Title: Re: husqvarna 445 wont start
Post by: phil1863 on June 04, 2017, 07:16:16 am
Thanks everyone for your valuable input.  Using the carb cleaner as a method to get the chainsaw to start I had read on another forum(wash my mouth out).  As suggested I obtained a compression tester and tested the compression.  I was fairly confident that it would be fine.  Wrong again!!! Either I am doing something totally wrong or the new compression tester is'nt working!!!  I tie wrapped the throttle, made sure the compression release button was fully up and pulled the starting rope at least 6 times.  The dial only shows 55 psi. :o.
As suggested I took the muffler off and looked at the cylinder.  In my novice opinion it looked fine.  No scractches that I could see, and the piston ring looked ok.  I am very dissapointed because I have used the saw so little.  What to do next??

Whilst waiting for the compression tester I did remember that last year ( at least 3 or 4 fuel fill ups ago ) that I very stupidly put chain oil in the fuel tank!!!  :-[. I know it was very stupid!!!!
I realised what I had done straight after, and quickly emptied and flushed the tank.  Could this somehow have lead to this problem???

My plan at the moment is to test the compression gauge on something else and see if it looks to be working, not sure what yet.

My second thought is could it be the compression release button.  I dont think so, as the reading is even lower when the button is depressed.  How can I check it though?

If the compression tester is ok (being new I would expect it to be) how should i take it from here.  I am still game to have a go at fixing it myself.  Before I do that I think I need to understand what i have done to break it in the first place.  I alway used husqvarna engine oil and mixed it to between 50:1 and 33:1. The strange thing is, as well that the chainsaw seemed to be cutting fine when I last used it and simply ran out of fuel???  Does that make sense?? In those last few seconds the engine started going faster like it always does when its about to run out of fuel.  It did'nt just stop, I turned it off!!!  Any thoughts?

Thanks again for your help!!!
Title: Re: husqvarna 445 wont start
Post by: Cut4fun . on June 04, 2017, 09:36:04 am
What compression tester? 
My cheap one has a valve in bottom and o-ring where goes into cylinder.

Have you checked your decomp valve yet?  Pulled it out and checked it?   Then stick a decomp plug in cylinder.

Title: Re: husqvarna 445 wont start
Post by: phil1863 on June 04, 2017, 02:45:12 pm
Thanks again for your quick response.  I bought the compression tester on ebay i.e.
The compression tester I received had no brand written on it, the details said Neilsen Tools...which I have never heard of.  The kit looks ok, but does it give the right value?  Tomorrow I am going to ask my neighbour if I can do a compression test on his stihl saw.  Its an old saw but still works very well, so I presume it will be over 110 psi.

I will remove the decomp valve tomorrow and try and order a decomp plug.

Thanks again
Title: Re: husqvarna 445 wont start
Post by: phil1863 on June 05, 2017, 12:35:49 pm
I tried the compresion tester on my neighbour's stihl saw and it measured 125psi which is probably accurate since it is quite an old saw.  This lies between the 110 and 150+ psi value that I have read is to be expected for a chain saw.  My saw reads no more then 65psi.  So its compression!!!!

I dont understand why since the cylinder and piston (what little I can see of it through the muffler hole) looks fine with no scratches.  I have always mixed the oil mixture to be between 50:1 and 33:1 (husqvarna oil) and the machine has been very little used?  I remove the crv and it looked fine.  I added fairy liquid aroung and on the crv and no leaks appeared to show.  I think I would have heard the air escaping anyway?

The only thing I can think of was that the chain oil that I accidently put in the fuel tank might have somehow caused this ( i had tried flushing it out, but maybe the residue that was left caused the problem, not sure how??). 

What causes might there be for the loss of compression?  I'm guessing
a) broken piston ring?
b) worn or badly scratched piston and cylinder?
c) leaking gasget?

Anything else??

I now need to find how to get the cylinder off of the 445.  I have not found any guides on line yet, but I will search later this evening.  I have found a 335 close will that be to the 445 I wonder?  I will try and get the carb off tomorrow.

I will add to this post what I find when I take the head off.

Thanks again for everyone's help.
Title: Re: husqvarna 445 wont start
Post by: 3000 FPS on June 05, 2017, 02:48:32 pm
Anything that can cause the saw to run lean will cause the scoring on the piston and cylinder.    This is due to heat in a lean condition.

Crank seals can cause this.
A bad intake seal.
Bad gas.
Carburetor set too lean.
Carburetor going bad.

The scoring goes across the rings and drops compression.
Or like you mentioned a broken or stuck ring.