Husqvarna 562XP - A Tale of Woe

[Bob95065]

I have a Husqvarna that I got not running in pieces. The piston had light scoring but the cylinder was clean. I got no other information with this saw like how this happened, how it ran, any history of problems, etc. I put a Meteor piston and a Caber ring in it and started the saw to be sure it ran. Once it started and idled a minute I immediately shut it down and took it to the dealer to get the data off the carburetor processor. They tested the fuel valve, temp sensor and throttle sensor and it passed. Then they flashed the saw and got the following information from it:



I wanted the tech to update the firmware but he talked me out of it. He said the numbers looked good and he recommended I leave it alone. In hindsight I should have insisted but I figured he knew more about these saws than I do since this was my first experience with Autotune.

Saturday I brought the 562 along with my antique roadshow saws to cut up some firewood. I ran a 20" bar on the saw for two reasons: first, I had a bar and a sharp 20" chain and second I didn't want to load the engine too much until the rings seated. It ran great and I heard a warble in the cut. when I went to idle it stopped. I started it again and cut a short time and it stopped. I went to start it and I got a sinking feeling due to low compression. I used my older saws the rest of the day.

I couldn't wait to get home to pull the muffler When I did I saw a scored piston. I went back to the hardware store/dealer for a couple of rubber stoppers for the intake so I could do a compression test. I ran into the tech who flashed my saw and an older tech that worked there. I told them what happened and we started going through causes for the failure. The older tech asked me what bar I was running and what I was cutting. I told him a 20" bar and logs up to about 16" or 18". He said that was a full bar cut that overloaded the saw before breaking it in. That didn't sound right to me because that saw can take a lot more bar than 20". Also they said running it wide open out of the cut would overheat it too. I thought that's how the computer tuned it. We agreed that I would bring the saw back after work today. I went home and did a vacuum test and the case held vacuum. I got the cylinder off and took the piston out. It's fried. What is more disappointing is the coating in the cylinder was compromised and it's not a paperweight.

Today we pulled the data off the saw and the tech said that it leaned itself out. This is what the printout said:



So comparing the two this is what I have:

In talking with him it isn't clear to me what these numbers mean. Does anyone have insight to what the saw did? Does anyone know what these numbers meana and what the scale is Husqvarna is using? I see that L went up 2 counts and H 15 counts. I don't know what this means.

If you look at the two scans above you will see that I ran that saw 7 minutes.

I had them update the firmware like I should have done the first time I went up there. This is what is shows:


So the firmware version went from 3.1.4 to 3.2.4. He said that was a big jump and should fix the problem. I noted that the numbers hadn't changed and he said they wouldn't until I started the saw. The thing is I feel like I am rolling dice here. I need to hunt down a new jug and slug and when I do I won't know if that computer will trash them in 7 minutes again or not. I think the safest thing to do would be to fix the saw, start it and let it tune then shut it down and take it back to see the tuning numbers on the printout. I read that the Duke's P/C sets are good quality, does any one have experience with them?

There's something to be said about two mixture screws and an idle adjustment screw. I like the spark advance but not the fuel mixture in Autotune.

Any help or comments are appreciated.

Bob

 

[ballisticdoughnut]

The saw must hold vacuum AND pressure. I’ve had saws hold vacuum but not pressure so I’d double check that. Have you cleaned the carb and installed a new kit? Fuel filter? Fuel hose? Pulse hose? All of those things need to be checked, and replaced if needed. Also the autotune should be reset to factory default settings after major repairs or fuel system repairs such as a carb rebuild.

 

[Bob95065]

The saw must hold vacuum AND pressure. I’ve had saws hold vacuum but not pressure so I’d double check that. Have you cleaned the carb and installed a new kit? Fuel filter? Fuel hose? Pulse hose? All of those things need to be checked, and replaced if needed. Also the autotune should be reset to factory default settings after major repairs or fuel system repairs such as a carb rebuild.

I went through the fuel hoses and they held vacuum. I did find a leak at the primer bulb base and replaced it. I thought I found the leak but I was wrong.

Impulse for the fuel pump goes through the intake so no pulse hose. I didn't rebuild the carburetor.

I posted on another site and got some good information. The initial numbers in the 80's should have been an indicator that the saw was pushing more fuel becaise it had a leak. The crankshaft bearings have plastic cages and one could have failed. The next step is to pull the seals and take a look.

 

[mbrick]

Did you perform a vacuum and pressure test?

Was the carburetor rebuilt with an OEM rebuild kit?

I agree that I don't think you burned it up just because of a 20" bar.

 

[singinwoodwackr]

Wow, what a mess. I’ll make sure to avoid these things
455 rancher. Leak in the oil pickup hose…waiting on the part.
seems to run ok although it idles a bit rougher than I would expect from this small a saw. Now I’ll pull the muffler and check

oops, wrong info...this rancher in not autotune...duh

 

[bwalker]

It appears to me you have an air leak. I would also never just throw a piston in a seized saw of unknown history without diligently looking for air leaks.
I would not use a Dukes Chicom cylinder and piston. OEM piston and cylinder kits for these are reasonable last time I checked.

 

[bwalker]

How about a pic of the piston?

 

[bwalker]

Wow, what a mess. I’ll make sure to avoid these things
i do have an autotune in the shop at the moment, hmm…
455 rancher. Leak in the oil pickup hose…waiting on the part.
seems to run ok although it idles a bit rougher than I would expect from this small a saw. Now I’ll pull the muffler and check

I don't know. Sure made troubleshooting easy. An air leak is no fault of AT and saws and two strokes in general have had air leak induced seizures since the beginning of the two stroke motor.

 

[HumBurner]

I don't know. Sure made troubleshooting easy. An air leak is no fault of AT and saws and two strokes in general have had air leak induced seizures since the beginning of the two stroke motor.

True, but the AT does a good job of concealing air leaks until they are about to do or already doing damage.

 

[bwalker]

True, but the AT does a good job of concealing air leaks until they are about to do or already doing damage.

Most guys that have air leaks will seize the saw, period. This is because they haven't a clue how to tune a carb, and don't verify tune every time they use the saw.
You often can't hear a lean condition with some or most motors while running the saw. In my case my hearing is such that I can't in most cases unless I well away from the machine and listening to someone else run it.

 

[Tomos770]

I have the same "disability"

 

[sean donato]

I'll just put this out there, you'll get 3/4 the cost of a new saw if you're going to replace bearings and need a new top end. The case takes some pretty expensive tools to split and reassemble. Actually a pre-built oem case is cheaper then just bearings, and the tools to do the job. The bearings had several updates over the years and were a known issue for failure.

 

[Tomos770]

 

[vintage_ridin]

I don't want to be that guy but what are you running for mix?
40-1
50-1
I have a 562xp I rebuilt and did a nice cleanup on the jug as well as blending the transfer ports
That saw only sees 40-1 though
Runs like a scalded dog pulling a 24' bar. But I also had to let it set itself right after the rebuild.
From what I remember you need to start it and just let it sit and run, let it idle for about 5-6 minutes.
Shut it down. Let it cool off, grab a beer and wait. Once it has, put the bar and chain on it. It's going to probably spin it as it had no drag or load on the drive line initially. You may need to set the chain brake on and it may die a few times doing that. Just blip the throttle gently. Once it simmers down again let it idle and work the revs up blipping it. Set it down. Let it cool off again.
On the third run of things, you are going to bring up the rpms let it come back down to idle and then keep working it. Eventually you'll need to ring it out and let it peak. It's going to tune itself doing this. If it sounds real high let off and bring it back up.
Once the saws richened itself up top and you'll know by how it sounds go cut come decent sized cookies with it.
I've done this on a bunch of them I've rebuilt and these saws are still running hard. The one I have gets flogged pretty hard by me personally and still runs like it's brand new. Zips right through a cut holding high rpm. If you change elevation alot it will dog out on you until it re tunes itself. It's a slow wonky system and I much prefer turning screws personally.