I bought a new Husqvarna 55 Rancher back in 2004, has always run great and I take good care of it. Moderate use (cut 2-3 cords of firewood each winter).
A few weeks ago it quit on me while in use, stalled after it was warmed up and I'd been using it for 20 minutes or so. I checked everything over and finally determined there was no spark. So I replaced the ignitor with an OEM and still no spark. I thought maybe the ignitor was bad, so I replaced with another OEM--no spark. I have the gap set exactly to spec., 3mm. I replaced the spark plug but no dice. I disassembled the switch to see if that was bad but everything looked fine. I cleaned the flywheel where the magnets are--nothing.
What could I be missing here? I'm usually pretty handy with engines and mechanical stuff (maintain my own vehicles, etc.) but this has me stumped. Could the flywheel be bad? A new one is $100, don't really want to replace that just on a guess.
How is the ignitor grounded? The mounting surface is plastic, but maybe the mounting screws thread into the metal block? I'm at a complete loss.
What further tests should I be doing? I'm about to give in and drop it off at a shop, but I hate to let this thing get the best of me! It's a pretty simple design, I ought to be able to figure it out.
Any ideas appreciated--thanks.
Not much left to check other than disconnecting the kill switch wire and removing plug cap to check for spark. The spark should jump ¼" in the air but the spark with "newer" higher voltage ignitions should be a little blue snap and is hard to see in daylight so I try to check in a darkened area.
The flywheel magnets should hold a screwdriver which some resistance to pull off. I have never had to replace one on any saw before.
Still no spark, can check (with ohm meter) for open circuit or short in the coil primary and secondary coil circuits and short between primary and secondary. Don't know the specs but try google / youtube for more info.
Is the flywheel to coil pickup gap too large? Slide in a business card, rotate the magnets to align with the irons and loosen the screws on the coil then retighten and roll it over a few times to make sure they still clear.
Any ripped pinched melted or nibbles wires? Maybe under the carb rubbed through or something?
You said you stalled the saw every time I've done that I've sheared the flywheel key off, it's easy to check with an impact to remove the flywheel nut and a block with a hammer.
I checked the gap, set it to 3mm which is factory spec.
Ignition wire, boot, plug are all new. Tried removing the kill switch wire.
Don't believe the flywheel key is sheared--by stall I just meant that in the middle of a cut it slowed down and stopped pretty quickly. How would that shear off anything? And anyway it should still spark, right?
How is that coil grounded? That's the only thing I can think of that might be wrong--but where it mounts is plastic, so cleaning that wouldn't do anything...
On a Husky 55 (or 50 or 51), the coil/ignition module mounts into the magnesium crankcase. So, if you're screwing into plastic, something is off. Maybe you have a Husky 455 Rancher. It has a weird shaped metal clip that connects a coil screw to the cylinder.
Disconnect the switch wire at the ignition coil, it could be grounding somewhere.
A new plug need not always be a working plug. If you have any other equipment like another saw or a brushcutter or something use a working plug from one of those as a test plug.
Quote from: dougand3 on June 01, 2018, 06:44:39 PM
On a Husky 55 (or 50 or 51), the coil/ignition module mounts into the magnesium crankcase. So, if you're screwing into plastic, something is off. Maybe you have a Husky 455 Rancher. It has a weird shaped metal clip that connects a coil screw to the cylinder.
No, this is the 55 Rancher, not the 455. Here's a picture of where the coil mounts. The mounting screws thread into metal sleeves in the plastic. Are these somehow grounded to the case? Could that connection somehow be broken?
(https://forestryforum.com/gallery/albums/userpics/50315/coil_mounting_surface.jpg?easyrotate_cache=1528307144)
Quote from: joe_indi on June 04, 2018, 09:29:10 PM
Disconnect the switch wire at the ignition coil, it could be grounding somewhere.
A new plug need not always be a working plug. If you have any other equipment like another saw or a brushcutter or something use a working plug from one of those as a test plug.
I did disconnect the kill switch, also tried 2 different plugs.
Quote from: Skeans1 on June 01, 2018, 12:16:10 PM
You said you stalled the saw every time I've done that I've sheared the flywheel key off, it's easy to check with an impact to remove the flywheel nut and a block with a hammer.
If the key was sheared, it wouldn't be moving the piston when you turn the flywheel, right? Based on the resistance I feel when the spark plug is installed, I think the key is OK. But at this point maybe I should check anyway...I'm kind of at a loss here.
In your pic, that's all metal. The coil screw hole will conduct to the cylinder. You can check with a multimeter - lead at coil screw hole wall and lead on cyl fin - probably 5 ohms or so.
The flywheel key can shear just a few mm and flywheel seats back on the taper. It will still spark but spark timing will be real early - piston halfway up on compression stroke. The piston will move normally. All that said - that's not the issue here.
Sounds like the only thing left to be wrong is flywheel magnets. Never seen it but heard of them going bad or polarity change.
Well if the coil is getting ground (test with ohm meter from coil laminates to cylinder).
Kill wire disconnected.
The coil gap is set correct.
The magnets still work.
Remove the plug cap and hold the wire ¼" or less away from the cylinder.
Pull the saw over fast enough.
Still no spark, you may have bought two bad coils.
Quote from: Hilltop366 on June 06, 2018, 05:19:36 PM
Well if the coil is getting ground (test with ohm meter from coil laminates to cylinder).
Kill wire disconnected.
The coil gap is set correct.
The magnets still work.
Remove the plug cap and hold the wire ¼" or less away from the cylinder.
Pull the saw over fast enough.
Still no spark, you may have bought two bad coils.
Is it possible that the spark plug wire is grounding somewhere and got abraded along the way to the point where it finally started arcing when you were mid-cut?
I tested for continuity between the coil body and the cylinder head--it was fine.
Regapped the coil again to 3mm. Put yet another new sparkplug in. No spark.
The only thing left I can think of to do is replace the flywheel. The magnets still seem strong, but I don't know what else I can try at this point. Hate to spend $100 on a guess though.
Maybe it's time to cry uncle and take it to a shop. Strange though--seems like a pretty simple system, ought to be able to fix it myself.
Maybe I miss read what your air gap is 3mm. It should be 0.3mm about the thickness a business card.
Check the compression. Steve
Hi I agree with decableguy2000 your air gap is too wide adjust it with a business card.All husqvarna 50-55 have a metal crankcase so grounding shouldn't be a problem.
I reset the air gap with a 3mm card that Husqvarna provides just to be sure it was exactly to specs. No change.
Either I got 2 bad brand new coils in a row (not very likely) or it has to be the flywheel.
Right?
You can try an aftermarket coil for ~$10 online. Or a used coil & flywheel combo is $35. Check ebay.
Quote from: Megunticook on June 11, 2018, 07:07:12 AM
I reset the air gap with a 3mm card that Husqvarna provides just to be sure it was exactly to specs. No change.
Either I got 2 bad brand new coils in a row (not very likely) or it has to be the flywheel.
Right?
I've sheared a flywheel key well still able to turn the crankshaft, your shaft is a taper fit so it's possible to lose time we'll still being tight.
It will be out of time but being solid state ignition, not the old points and condenser, it will still spark. I am thinking the module is not grounded or the kill wire is rubbing somewhere.
When this happened on my 395 I lost spark as well.
Not the kill switch/wiring because it wouldn't spark even when I disconnected it from the coil.
Not a bad ground because I tested with multimeter.
Spark plug wire is brand new (factory installed to coil).
Compression? Maybe, but why would it suddenly lose compression? I'll see if I can get a gauge and test.
I'll pull off the flywheel and see if anything looks odd there.
Quote from: Megunticook on June 14, 2018, 08:03:44 PM
Not the kill switch/wiring because it wouldn't spark even when I disconnected it from the coil.
Not a bad ground because I tested with multimeter.
Spark plug wire is brand new (factory installed to coil).
Compression? Maybe, but why would it suddenly lose compression? I'll see if I can get a gauge and test.
I'll pull off the flywheel and see if anything looks odd there.
Testing continuity with a multimeter only indicates circuit integrity, not the circuit's ability to conduct a load. It is possible to obtain an OHM reading that is withing normal range with no load, but not sufficient to do work.
The picture of the coil mounting seems to show potential for a poor ground. A better method for load testing circuits is to load them with a test light bulb. In the case of a unit with no battery this means hooking the test light lead to a positive battery terminal, provide a ground lead from the battery to a common metal ground on the saw, then touch the test light probe to the coil mounting. The light should shine properly if the ground is good.
Another quick way to check and see if there's anything at all is lick your fingers grab the plug touch the cylinder and pull the rope, better yet call a buddy.
I finally took the saw to a mechanic, in about 5 minutes he figured out the cylinder head was scored which shot the compression. Pretty humbling!
He said may as well buy a new saw by the time you pay for a new head and cylinder. Well, I checked online and found an OEM for about $100, so I bought it. Just removed the old cylinder today and am all set to put the new one in.
Question: it comes with new bearings. What should I oil these with? Or grease?
Also, should I oil the cylinder and head before assembling? What oil?
And once it's together, does it need to be gently broken in before using it hard? What's the procedure to do that?
The saw was new in 2004 and I've tried to take pretty good care of it. Doesn't see a ton of use, probably run through 10-15 tanks of fuel each year cutting firewood. I suppose 14 years is nothing to complain about, but I'm wondering what I did wrong to cause the wear? Obviously it got too hot--the scoring is all on the exhaust site of the piston/head.
Could that be from running it lean when it runs out of fuel (I should probably not run it dry like I had been doing at high RPM)?
Or maybe I had the carb adjusted too lean? I tried to err on the rich side, but I'm not a pro so maybe I got it wrong. I used a tach and my ear (listening for the "burble" at idle and avoiding the high RPM "scream").
I did catch myself forgetting to close the warm air inlet after one winter, maybe that did it. I probably ran it a few tanks before realizing my mistake in warmer weather.
In any case I'll be very careful with it from now on. Maybe I should let a pro teach me how to adjust the idle just right.
For your wrist pin bearing and cylinder use the same premix that you normally use. Run it rich for let's say a tank or two minimum then lean her out to get your burble, make sure your air filter stays clean.
Quote from: Skeans1 on September 19, 2018, 11:32:48 PM
For your wrist pin bearing and cylinder use the same premix that you normally use. Run it rich for let's say a tank or two minimum then lean her out to get your burble, make sure your air filter stays clean.
You mean lube the bearing with fuel? I would think you'd want to use some oil or grease in those bearings.
As far as the carb mixture needles, any specific guidelines on how many turns to back them out from lightly seated?
Comparing the two heads, I notice what looks like maybe a decompression hole drilled into the new one. (I also noted that the original is stamped "Mahle 46ZD5++" but the new one has the Husqvarna logo and 5039377). Is that decomp hole for easier starting? Is there something I can install there? My original saw didn't have it.
Quote from: Megunticook on September 21, 2018, 07:59:24 AM
Quote from: Skeans1 on September 19, 2018, 11:32:48 PM
For your wrist pin bearing and cylinder use the same premix that you normally use. Run it rich for let's say a tank or two minimum then lean her out to get your burble, make sure your air filter stays clean.
You mean lube the bearing with fuel? I would think you'd want to use some oil or grease in those bearings.
As far as the carb mixture needles, any specific guidelines on how many turns to back them out from lightly seated?
Comparing the two heads, I notice what looks like maybe a decompression hole drilled into the new one. (I also noted that the original is stamped "Mahle 46ZD5++" but the new one has the Husqvarna logo and 5039377). Is that decomp hole for easier starting? Is there something I can install there? My original saw didn't have it.
No with your premix oil that you add into your fuel.
I'm missing something here. How does the new piston/cylinder fix the spark problem? Were you assuming no spark because it didn't fire? You can test the spark by removing the plug, re-inserting it in the plug cap, resting it on the cylinder when you pull it over and looking for the spark. And yes, oil the pin bearing and a light coating on the piston and cylinder wall with straight mix oil as mentioned. You will need to find a metric plug (short bolt) to plug the decompression port.
I've had a hundred or so people bring me their saw with "no spark" all seized up. you should find out why yours seized,or it will do it again. when I ask'em did it die in the cut most say yes. i' tell'em it seized, and they say no it turns over :) what causes that??
Quote from: Skeans1 on September 21, 2018, 08:18:19 AM
Quote from: Megunticook on September 21, 2018, 07:59:24 AM
Quote from: Skeans1 on September 19, 2018, 11:32:48 PM
For your wrist pin bearing and cylinder use the same premix that you normally use. Run it rich for let's say a tank or two minimum then lean her out to get your burble, make sure your air filter stays clean.
You mean lube the bearing with fuel? I would think you'd want to use some oil or grease in those bearings.
As far as the carb mixture needles, any specific guidelines on how many turns to back them out from lightly seated?
Comparing the two heads, I notice what looks like maybe a decompression hole drilled into the new one. (I also noted that the original is stamped "Mahle 46ZD5++" but the new one has the Husqvarna logo and 5039377). Is that decomp hole for easier starting? Is there something I can install there? My original saw didn't have it.
No with your premix oil that you add into your fuel.
Got it!
Quote from: lledwod on September 21, 2018, 11:55:27 AM
I'm missing something here. How does the new piston/cylinder fix the spark problem? Were you assuming no spark because it didn't fire? You can test the spark by removing the plug, re-inserting it in the plug cap, resting it on the cylinder when you pull it over and looking for the spark. And yes, oil the pin bearing and a light coating on the piston and cylinder wall with straight mix oil as mentioned. You will need to find a metric plug (short bolt) to plug the decompression port.
Didn't fire because not enough compression. Is there a decompression gadget for easier starting? I know the newer Ranchers have that....
Quote from: FYRWOOD GUY on September 21, 2018, 01:29:22 PM
I've had a hundred or so people bring me their saw with "no spark" all seized up. you should find out why yours seized,or it will do it again. when I ask'em did it die in the cut most say yes. i' tell'em it seized, and they say no it turns over :) what causes that??
Not seized. Just the piston and head were scored near the exhaust port, so no compression.
But what is being said is.. compression or otherwise, scoring or otherwise, it should still have had spark showing as long as it could still be pulled over..
Sounds like there is or was at least 2 separate issues going on in order for it to die on you.. or at least one that possibly brought both to a head, ending up finally toasting the piston and jug.
Without looking into why it had little or no spark (if in fact it didn't) or why it got so hot or lean, you may just be putting all of the labor and new parts involved, at risk for the same scenario to occur all over again!
Quote from: realzed on September 21, 2018, 04:22:31 PM
But what is being said is.. compression or otherwise, scoring or otherwise, it should still have had spark showing as long as it could still be pulled over..
Sounds like there is or was at least 2 separate issues going on in order for it to die on you.. or at least one that possibly brought both to a head, ending up finally toasting the piston and jug.
Without looking into why it had little or no spark (if in fact it didn't) or why it got so hot or lean, you may just be putting all of the labor and new parts involved, at risk for the same scenario to occur all over again!
The mechanic I took it to got it to spark right away, so apparently I was wrong about that.
Not sure of the overheating cause--my guesses are:
- running the fuel tank dry at high rpm and load (mixture goes way lean)
- leaving the warm air inlet open briefly after one winter
- mis-adjusted carb.
From now on as soon as I hear it's running out of fuel I'll stop and let it idle until it dies. I'll make sure I don't ever leave that warm air inlet open when it's above 20 degrees F. As for the mixture, maybe I should check with a pro. after setting it but before using it to be sure I have it right.
Question--I've got the new piston on and am ready to assemble the head. I've got a new gasket--does it assemble dry or should I use some sealant?
Thanks for help everyone. First chainsaw rebuild--hope it's my last (unless I'm helping a friend!).
I use some light grease to help stick the gasket to the cylinder,and some on the crank case also.
make sure the intake manifold has no stripped threads, and the rubbers are not leaking. that model is famous for that problem.
it's a real good saw otherwise!! hope you get'er figured out. I've seen a few burned up because of the open window.
Glad you are getting it figured out!
Not sure why you are running your saw dry of fuel, for long term storage I'm guessing.
I have had one of my saws since 1989 and have never ran it dry to store, it has sat for as long as 3 years and started up in 4 pulls (perhaps I'm lucky), all I do is dump the fuel out of the tank and put in fresh fuel. I do use non-ethanol fuel and a two cycle oil with stabilizer in it (usually Stihl oil). I do know I have put in at least 1 carb kit in it in the last 29 years.
To me running the saw out of fuel is going to add extra wear, When cutting wood I shut it off at the first sign of running low and refill.
Quote from: FYRWOOD GUY on September 24, 2018, 05:57:19 PM
I use some light grease to help stick the gasket to the cylinder,and some on the crank case also.
make sure the intake manifold has no stripped threads, and the rubbers are not leaking. that model is famous for that problem.
it's a real good saw otherwise!! hope you get'er figured out. I've seen a few burned up because of the open window.
Thanks for the grease tip. I'll take a close look at the intake manifold on reassembly.
Probably was that stupid "window." Kicking myself. Oh well, I guess now I'm learning how to rebuild a saw.
Quote from: Hilltop366 on September 24, 2018, 08:06:55 PM
Not sure why you are running your saw dry of fuel, for long term storage I'm guessing.
Foolish habit, probably from all the warnings I hear about ethanol, but as you say no need to subject the engine to those lean conditions unecessarily.
So after I get everything buttoned back up, do I understand that factory settings on the 55 Rancher are 1-1/4 turns out from lightly seated on both H and L screws? And run it that way for 8 tanks or so, then readjust?
And...should I do the main bearings now? The crankcase doesn't look too dirty, although it's not spic-n-span either. I'd really rather get the thing back in service ASAP, but after 14 years of light/moderate use am I better off to replace those bearings now?