iDRY Vacuum Kilns

Sponsors:

can't get my Husqvarna 55 Rancher to spark

Started by Megunticook, June 01, 2018, 08:33:48 AM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

Megunticook

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.

Skeans1

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.

Megunticook

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.

Skeans1

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.

lledwod

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.

FYRWOOD GUY

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??

keep your SHARP chain tight don't force a dull chain to cut

Megunticook

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!

Megunticook

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....

Megunticook

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.

realzed

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!  

Megunticook

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!).

FYRWOOD GUY

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.
keep your SHARP chain tight don't force a dull chain to cut

Hilltop366

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.

Megunticook

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.

Megunticook

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?



Thank You Sponsors!