Stihl 024AV died

[rd35]

Just throwing this out for consideration. I had my plug wire cap lose connection with the plug wire a few years ago. Have heard others who had the same problem. Easy to check. Just spray some lube on the wire at the cap and push the cap down the wire exposing the connector spring wire. Look to see if the steel spring wire is burned where it pierces the plug wire insulation. If so, get a new spring connector. If not, re-pierce the connection to make sure it has good connection to the conductor material inside the plug wire.

 

[Okie]

Just few hints about checking your saw yourself.
You better keep a heads up when doing compression checks on chainsaws or you will get false bad low readings from most gauges if the set-up is not for a small 2 cycle engine and YOU really don't know if your gauges work correctly on a good saw.
If it was sitting and idling and died and been running good it's probably not compression. You can also get a general compression idea from the pull of the rope on a Stihl saw.
Put a new plug in it, squirt of mixed gas in the carb throat, no choke and full throttle and it should pop, if no pop, gap a old plug at about .050 and watch for a good spark to jump the gap in a darkened room with regular spark plug removed so as you get a good spin.

Summary: If you are not familiar with your compression gauge and checking chainsaws compression you can get easily mislead into thinking you have a bad powerhead and the problem is YOU using the wrong test eq and test procedures.
At least do a compression test on a saw that is running good to see if your gauge is capable of reading compression on a good saw. You will probably get a big surprise if you are using a automotive gauge. Quite common for some gauges to only read 35 to 50 PSI when it's actually 125 or more.
If it's a old points/condenser ignition system and weak spark, might even be a $4 condenser and you can easily get mislead and toss a good powerhead thinking it's low compression and then spending big bucks to replace your tossed saw.
read this article and pay attention to using compression gauge testing on small 2 cycle engines.
http://www.klemmvintage.com/squish&comp.htm

 

[GLOCKED]

I had this happen on my Stihl 020 AV top handle. Spark was there but it was weak. New points, condenser, a plug and it has been running like a champ since!

 

[Wood Doctor]

Take 5 min. And pull the muffler, check the condition of the piston.

Agreed. If he has a spark and fuel is making it to the combustion chamber, it will not run if there is no longer enough compression. Most likely, the top end must be rebuilt. Piston and ring kits are still readily available. I have rebuilt several Stihl 024 AV's and they all run afterwards. Occasionally the carbs need to be replaced or rebuilt, but without compression, that's a fruitless endeavor.

 

[grizz55chev]

Still waiting on an answer as to what was the prob from the OP, What's up Bob393?

 

[pioneerguy600]

His post, number 7 says the piston had scoring, not sure how bad that scoring was.

 

[bob393]

There is a small amount of scuffing on the front of the piston but I have seen much worse on a running saw. I can't tell if the rings are free but there is not much carbon in there. I just purchased some pre-mixed high test gas and synthetic oil mix to give it a shot, stupid consumer product from Lowes so you can tell I'm grasping at straws here, and it still will not pop. What on these saws can change in an instant? Like I said it was running perfectly, I sat it down, it stalled and now it will not start or even pop?

 

[grizz55chev]

Still chasing your tail if you don't test three things, compression, vacuum and pressure.

 

[bob393]

I feel I'm defiantly chasing my tail here.

I missed a couple of posts om the second page so:

I guess my automotive compression tester defiantly will not work for this not to mention the plug will not clear the cooling fins to screw it in.
The only reason I have not checked vacuum or pressure is that by squirting fuel in the carborator I'm bypassing all the carb functions. I just want to hear it pop
so I can move on. I think I'm ready to buy a small engine compression tester though.

 

[GLOCKED]

Check my above post. Like someone else mentioned even just pulling the engine over you can kind of tell with the compression. If you have a weak spark it just sounds like what I experienced.

 

[bob393]

That is what is so frustrating, The compression when pulling it over feels like it always does and there is plenty of spark.
Perhaps the new plug is bad, that's my next thing replace the plug again.

 

[GLOCKED]

Just from my experiences, the cheap points, condenser, wire, and plug have fixed several of my engines. 2 stoke and 4 stroke.

 

[bob393]

Ran into town and got another new plug, no difference.
I just ordered a flywheel puller to dig in deeper.

 

[bob393]

OK so I couldn't wait ant got the flywheel off the old fashioned way with wedges and a hammer, nope didn't damage the threads either.
The key way is fine and all looks good.
Since this saw is electronic ignition with no points and condenser do we think it could be the ignition module/coil because
I'm still not convinced it's the top end.
Or would you get a new compression tester and go from there?

 

[bob393]

Does anyone know what the internal resistance is for the coil on this thing?
Mine is 7.28K ohms from the spark plug wire to ground. Or 7.28 on the 20K scale.
and 1.3 ohm on the primary, or 1.3 on the 200 scale
Sound right?

 

[bob393]

No one?
I don't have a book on this saw or I would look it up.

 

[Phil_C]

According to the manual it only say;

Accurate testing of the ignition
module is only possible with
special test equipment. For this
reason it is only necessary to carry
out a spark test in the workshop.
A new ignition module must be
installed if no ignition spark is
obtained (after checking that
wiring and stop switch are in good
condition).

It also goes on to say:

Ignition timing is fixed and is not
adjustable.
Since there is no mechanical wear
in these systems, ignition timing
cannot get out of adjustment.
However, an internal fault in the
circuit can alter the switching point
in such a way that a spark test will
still show the system to be in order
although timing is outside the
permissible tolerance. This will
impair engine starting and running
behavior.

Also check your ground lead. I have seen it happen before where when the plug lead is pulled out of position the ground lead works as intended but put the plug back in and the lead on the plug and the ground lead short circuits the spark.

 

[Okie]

You can get Stihl generic solid state ignition systems from ebay for around $15 with free shipping.

Give that a shot first.

I've seen solid state ignition coils test good on a ohmmeter but not operate at all. their are solid state devices inside (that the ohmmeter don't see) to control the triggering, etc.

I've also seen the non electronic magnetos test good on ohmmeter and coil testers and be weak.
If a coil don't fix it you will have have a good spare coil when you do get it running.

 

[bob393]

15$ is cheaper than a new compression tester since mine will not clear the fins on the cylinder head.
I even tried the youtube thing of opening the gap on an old plug to about 1/4 inch and I still get a strong
spark but that doesn't speak to the internal electronics for timing I guess. I'll try the module than cuz this is
just killing me!

 

[Ax-man]

It has been a long time since I have posted in the chainsaw forum. Lot's of good advice here. I'll toss my little two cents .
When you tried to prime the saw directly through the venturi of the carb did you choke it in some way, either with the air filter on or placing your thumb over over the venturi??? Shouldn't make a difference but might help to get it to pop.

Compression check can be done with just the starter rope. Lift the saw by the starter rope good compression will hold the weight of the saw. Even it bumps down slowly your still good. If it runs down the rope fast then you have a problem.

If your getting spark with a 1/4 inch gap on a grounded plug I would say your good to go on that one.

My guess on your initial problem of no start after shut down is fuel starvation , bad filter in tank, tank vent clogged, plugged up carb or an air leak of some sort which could be a leaking intake boot , pulse line bad, leaking cylinder base gasket , crank seals are bad. If I had to choose it would be plugged fuel filter or tank vent or plugged carb. Air leaks cause running problems but can also be a be cause for hard starting after the engine gets warmed up. It is hard to find some of these air leak problems without some sort of vacuum and pressure testing tools. If your saw was running good as you say and just quits it has to be something minor.