Stihl 046 Magnum Piston Help

[log_jammer]

Also, if you were able to find a complete 046 Magnum for $100 ... YOU SUCK!!! Sorry, I couldn't resist.

 

[JWMUSTANGMAN]

Also, if you were able to find a complete 046 Magnum for $100 ... YOU SUCK!!! Sorry, I couldn't resist.

Yea it was a steal I know. I got em down from 150 even! It served me well for 10 years or so. I'd love to get it going again.

 

[JWMUSTANGMAN]

I'd say it's just a simple question. Did you replace the crank seals when the saw originally failed? I reread your original post and did not see them listed. I'd say if you still had an air leak, it would run about ten minutes before locking up. Don't ask me how I know. I've done the same. Also, I don't think it's the Farmertech kit, or the big bore.

Ok thanks for the insight. No I did not replace the crank seals. Maybe a dumb question, but where are they and how do you replace them?

 

[backhoelover]

So how do you break one in? Just run it high throttle without cutting for a few tanks of fuel?

yes. that is how i do it, every person has their different way

 

[alexcagle]

I gravitate towards leanout condition as well. Really dry looking. I dont see any oil residue at all. What are the spark plugs' numbers?
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Intake boot split leak?
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Screen in carb clean?
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Fuel filter changed?
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For safety sake, new fresh fuel?
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Tank vent tested?
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Did you reuse the oem base gasket, or use the chinese one with the kit?
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It's difficult on that saw, but I would verify that the bearing races are intact by looking with the cylinder and piston off. I had a similar saw a few years back that passed vacuum/pressure, but a crank bearing with a bit of the race missing caused problems, and leaked at high rpm.
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Verify that there is no up/down play on both the flywheel and clutch side.
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I don't break in saws. Never have. I was told in school not to piss rev under no load conditions on chainsaws, but as far as break in, none. Tune and go.

 

[drf255]

You fixed a symptom without finding the cause. You have a lean condition. You can put 100 more top end so that saw and you will get the same result unless you fix the problem.

Look up vacuum testing a saw. You'll need to do this. Chances are your stock top end can still be saved and it will outrun the AM kit you are running now.

You should also clean your carb out and change your fuel line and filter. You got 10 years out of the saw and the new fuels aren't kind to the fuel system.

Look up saw tuning as well. If your adjusting the H side so that the saw screams, that's wrong also. It should sound like it's slightly misfiring at WOT and sound clean when you cut wood.

As for breakin, I've ported 30 saws at this point and have never broken one in at all. No issues so far. Start them fat, goose a few times and tune them slightly fat, then put them in wood and run it like you stole it. Knock knock, haven't had an issue yet.

We all start somewhere and you've got a lot to learn to fix this issue. I've learned a bunch here and made the same mistakes I'm telling you not to above.

 

[alexcagle]

And by "fat" @drf255 means open up the "H" carb screw about 1/4 to 1/2 turn more than the standard setting (counterclockwise) to enrichen the fuel to air mixture, to oil everything up Internally during first run.

 

[JWMUSTANGMAN]

Ok I'll read up on crank seal checking. Also, I used "opti-2" 2 stroke mix this time. I've never used it before.. Even after I mixed it and shook it up really good and everything, it looked like pure gas going into the saw. No green or blue tint to the liquid or hint of oil smell like I am used to seeing from my other mixes. Could the mix just have been crap?

 

[blsnelling]

You MUST vac and pressure test this saw. Anything less and you're asking for the same results again. Also, tuning is critical. If tuned too lean it will cause the same result. I also highly recommend that you clean and put a kit in the carb. You should also inspect the intake boot, impulse line, and fuel line. Break-in? Tune it a couple hundred RPMs rich and go cut wood…WOT throttle.

http://www.arboristsite.com/community/threads/chainsaw-tuning-101.250802/

 

[JWMUSTANGMAN]

Ok I intend to do those tests. I am working on getting a pressure and VAC pump to do them. I don't have one right now. Is there a chance the oil that I use to mix was just poor quality? I have never used it before and it did not have the look or smell I am used to seeing with my two-stroke mix. Thanks for the link on tuning. I will read up on that as well.

 

[JWMUSTANGMAN]

Either way I have to have another piston and cylinder correct? I should go ahead and order them and then do the pressure test before I tried to start it?

 

[drf255]

No. Test first. You can likely clean up your old cylinder.

You'll post pics if it here and we will help.

 

[blsnelling]

Do you still have the original cylinder?

 

[JWMUSTANGMAN]

I do still have the original cylinder. I can get pics of it tonight. This is the replacement that only ran for like 10 minutes and then locked up. I had to use a wooden dowel in the spark plug hole to tap the piston out of the cylinder. It was stuck good.

 

[JWMUSTANGMAN]

How would I clean these up? And how would they seal with those scrapes? Would I need new piston rings? Or just take everything apart, smooth out the rough edges, and put it all back together, then pressure test? And I need 3 separate tests, correct? Combustion chamber compression test, crank case pressure, and crankcase vacuum, right?

 

[blsnelling]

That is aluminum transferred from the piston. It will clean up with acid and/or wet/dry sandpaper of 220-400 grit.

 

[Paragon Builder]

Hopefully it's just aluminum transfer from the piston. It often is. Here is a link to a video on removing transfer

You will want a new piston and rings, and if possible save the oem cylinder like Al said.


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[JWMUSTANGMAN]

Ok I'll try to clean up the original cyl. Thanks for the help guys. I want to get this thing going. None of ya'll are in east TN are you? Lol I'd love to wank through this with somebody. I've got a o64 and an 075 I need to do too. I want to get my 046 right first tho.

 

[Paragon Builder]

The guy in the video is in Jamestown.


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[clintb]

You think the plating at top of exhaust port may have chipped off? For $23 I would just get a new p/c