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stihl 460 scored jug and piston

Started by Randy88, July 02, 2016, 06:19:38 AM

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Randy88

Bought this saw new about five years ago but could be more time fly's.     About two years ago we scored a jug and piston and my fix it guy put a new aftermarket in, which seized on start up, so he put a new stihl jug and piston in.   

This week we fried another jug and piston.      I'll admit, I don't adjust the saw's myself, I always take them to my dealer/fix it guy and he adjusts the carb on them for me.     

Now I can put another new jug and piston in this same saw,
or trade it off for a new saw the same size?? 

I run three stihl saws, all bought new, use the same gas mix out of the same jug and don't meddle with the carb setting myself, leave it the same as my dealer adjusts it and if we have issues, he adjusts the carbs.       

Does the 460 have issues and should I trade it off for another new saw or put another new jug and piston in and keep running it for a few years??

Basically what would you do if it were your saw?     

John Mc

Makes me wonder if you've got an air leak somewhere.
If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow

farmguy

Or water in your fuel or bad oil.what do you mix your oil too. I use sthil brand oil works very well. If you don't adjust the saw yourself check your spark plugs once a week. They should be a almond brown. Black is too rich but wont make it blow up. Wite is bad too lean. Makes it run too hot with not enuf lubrication so double whammy. I suspect that the saw might have other issues the fixer overlooked.

DelawhereJoe

You say you run 3 saws all with the same gas mix and everything, does the 460 get run the most out of the 3 of them.
WD-40, DUCT TAPE, 024, 026, 362c-m, 041, homelite xl, JD 2510

Randy88

I only use the stihl silver oil mix, synthetic oil I think, never mix it with any ethanol, only unleaded gas, all three saws get fueled up out of the same mixed gas can and if anything, we mix the oil somewhat heavy, the mix are for 2.5 gallons of gas and my jug is only 2 gallons in size, used the same jug for decades now, on about six different saws and we've always had two saws at a time, until the last few years when we bought another so now we run with three at all times.   

As for water in the fuel, I wouldn't think so, if that were the case, all three saws would have the same issue.   

As for an air leak, could you explain this somewhat more in detail, why would it cause a fried jug and piston and where would I start to look??

As for the saw usage of the three, the small saw, 362 gets about twice the usage compared to the next used saw which is the 460 and the 660 gets the least as a whole.   


OneWithWood

I have changed out piston and jug on my 460 two times.  The cause of failure I believe was an air leak.  The first replacement lasted a brief time.  For the second one I used silicone on the base gasket and let it cure before firing it up.  That was over a year ago.  Be sure and do a vacuum test after replacing the jug and piston.  My 460 is my primary firewood bucking saw and sees a lot of use.  It is beginning to increase rpms when vertical and at WOT so I know it is time to re-torque the jug screws and check the exhaust to jug screws.
I used genuine Stihl parts for the first replacement and Meteor parts the second time.  It is my understanding that Meteor makes the Stihl OEM parts.
One With Wood
LT40HDG25, Woodmizer DH4000 Kiln

joe_indi

Randy88, the MS460 is one of the best chainsaws in my opinion. I know  users who cant read and write  but have the  460s  surviving more than a decade of misuse.
So you just need to find the cause of the problem and fix it and you will have a very eager saw.
If your fuel is good, I would look at a couple of other things.
Whether,
the pickup body in the fuel tank is blocked
the impulse pipe is partially blocked
the strainer in the carb is blocked
a faulty jet valve
too low a metering level
wrong jet size (std is 68, high altitude is 66, safe is 70)
worn out diaphragms
a couple of cylinder screws are loose
oil seals are leaking
wrongly adjusted H and L screws
the exhaust is leaking (more seizure on the front clutch side)
We have saws here with deep scour marks that are still running. It is pretty difficult to kill a 460s. And, like Al Smith remarked the engine can still run with an imperfect piston or cylinder.
Joe


joe_indi

Could you up load a few pictures of the damaged areas of the cylinder and piston, and a shot of the cylinder base and crank shaft

Randy88

I don't have the saw, we dropped it off at the dealer and he called to tell me the piston and jug are scored, I have yet to see it myself firsthand, haven't had time yet to go look, he quoted me a trade price and fix price and have yet to decide which way to go.    We'd been running it and it ran nice, fueled it up and couldn't get it to start to save our lives, so into the dealer it went.   

We all love the saw, we'd considered trading off my 660 for another 460 and then have two of them, but I've drug my feet and hung onto the 660 for larger logs.   

I won't know much more about it till next week, I'm just looking for idea's or thoughts on others that fix them or work on them.   So I can ask questions as to what has been done to the saw, or what maybe to look at, my fix it guy is pretty picky and has done a good job over the last nearly 20 years of working on my saws.


motohed

I'm thinking air leak , it may be the the carb boot , pulse line , or crank seals . I would do a preassure test before taking the saw apart .  It may be , some lose carb screws make sure they are all tight . If it's crank seals , I always replace the crank bearing .

CTYank

Not having seen the scoring, assuming what it looks like, on the third go-round I'd be asking mr-fixit What. There's clearly a big systemic problem with this saw, getting expensive, and simply unacceptable. Almost certainly something(s) are causing the mixture to go dangerously lean under load.

As Joe listed the usual suspects, they should all be completely eliminated before you consider returning this saw to normal duty. And, for a trivially-simple, any-old-time mixture check: with saw warmed up, in a cut quickly lift the bar with throttle held wide-open. Engine should 4-stroke noticeably. If it doesn't, it's too lean, resolve that problem before running it further. Unless you have a skid of p&c-s & lots of time.

Lots of sample vids on YouTube of "4-stroking" of 2-stroke engines.
'72 blue Homelite 150
Echo 315, SRM-200DA
Poulan 2400, PP5020, PP4218
RedMax GZ4000, "Mac" 35 cc, Dolmar PS-6100
Husqy 576XP-AT
Tanaka 260 PF Polesaw, TBC-270PFD, ECS-3351B
Mix of mauls
Morso 7110

Al_Smith

With no malice intended towards the dealer and as a general statement sales people only make money if they sell something .Some,not all have a tendency to take advantage of a persons lack of knowledge concerning various things .

Repair shops ,saw,automobile etc. usually charge a fee to inspect for damage .If you purchase a new item they often wave the fee .It's an old game many play .Fact I've lost track of how many chainsaws I've repaired that a dealer said were  beyond hope and most are still in operation today .The repair of same if done by a shop would have exceeded the value of the saw.

In addition most dealers use a flat rate book for common repairs.It's not actual time worked on .I have the older flat rates for Stihl,Homelite and McCulloch .The amount of labor units far exceed the actual time invested .Car dealers are very much the same .Just the facts of life,like it or not .

Walt

^^^  Reading this had me wondering whats up with the repair guy. No disrespect but??????
MS461R, MS290, MS170, Homelite XL, Dirty Hand Tools 27T splitter, Kubota B20 FEL&BH, Timberjack Woodchuck, US Stove Co. 2421 for heat. Too many Wheel Horse Garden Tractors..

John Mc

Quote from: Walt on July 03, 2016, 09:39:27 AM
^^^  Reading this had me wondering whats up with the repair guy. No disrespect but??????

Fixing the symptom, but not the cause.  It's like constantly fixing flat tires on your car, but not bothering to pick up the nails in your driveway.
If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow

LeeB

When did you come to my house? You should of come while I was at home.  :D :D :D
'98 LT40HDD/Lombardini, Case 580L, Cat D4C, JD 3032 tractor, JD 5410 tractor, Husky 346, 372 and 562XP's. Stihl MS180 and MS361, 1998 and 2006 3/4 Ton 5.9 Cummins 4x4's, 1989 Dodge D100 w/ 318, and a 1966 Chevy C60 w/ dump bed.

farmguy

That's why I learned to fix stuff myself. With a 90% success rate I have no one to blame but me for the other 10% lol

John Mc

Quote from: LeeB on July 03, 2016, 11:34:30 AM
When did you come to my house? You should of come while I was at home.  :D :D :D

Actually, i was referring to my house. For a while there, I was ready to ask the guys at the shop for a bulk rate on tire repairs.
If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow

Texas-Jim

I am a Stihl mechanic but though the years i have figured out a few things. Stihl is one of the best out there, there are several others as good. But any two stroke failing that often isnt a problem with the saw. There are a bunch of things that can cause failure. Fuel, Air leak, wrong oil or not enough, yes even too much oil can lean out an engine, extreme over revving. Any time i have an engine fail i find the reason first, throwing a piston and cylinder at it is not a fix in my opinion. Any mechanic that does not find the reason and just throws a part at it needs to go sell cars or something. If you have never used it this is a Stihl check list, if you cant figure out a problem it really helps.
What we do in life echoes through eternity.

Randy88

Whoa, hold up a minute, yes it might be easy to blame others for my troubles, that's not the reason I started this thread, the reason I started it was to ask questions, I'll admit I don't like small engines, large diesel's, transmissions, final drives or dozens of other things I can handle with ease, small engines not so much.

I've run saws my entire life, some we worn flat out, others were discontinued and could no longer get parts for and the list of reasons for buying new or used saws is endless.       

The reason for this thread is to figure out what happened, how it happened, what to look for so it doesn't happen again, how to tell what went wrong and etc.   

The saw was in my or a family members hands when issues arose, it didn't just come from the fix it shop, we've been running it for months, some day's hours on end, some day's it never starts.     I'd hate to venture a guess as to how many hours are on the saw since the last jug and piston were installed, guessing over a  hundred, doubt two hundred, but I don't know for sure, usually when we run them we're bucking up firewood, all day long, day's on end, weeks at a time.     

The reason for the thread is this, I didn't see anything a miss, didn't run differently, sound differently, mixed the gas any different, so if I was to blame, which is where I'm thinking the blame lies, I'd rather know what I did wrong or didn't do right however you want to view it. 

As they say, nothing ever broke sitting on a shelf or wrapped in a case in the store waiting to be bought, it breaks while using it, either from wear and tear, abuse, neglect or a flat out brain fart moment and most knew better in the first place.     

The reason for the thread is.................I don't know and am wanting to know because beyond the finger pointing, its happened before, same ordeal, same scenario and when I took it in, he knows me well enough that I want answers as to What happened and after it was discovered, nothing seemed amiss, I looked it over the last go around and with the exception of a scored jug and piston, everything looked fine and all we came up with was, maybe a fluke, which isn't out of the ordinary in my life, with all the equipment I own and run, things do happen, things wear out and nobody is to blame but hours of use.   

Can an air leak just happen, if so, how do I know when something is wrong, of all the idea's everyone has offered, first and foremost thanks, none I'd have ever come up with on my own, second, how do I narrow it down as to what went wrong and mostly, how long did we run it to cause the issue at hand??

I'd trade for a new saw, get a one year warranty and after that, how would I know if something was amiss with that saw??   Hence the reason for this thread.   

DelawhereJoe

If you run the 362 double the time then the 460 things should have happened to it first if it was fuel or operator error. The saw going bad as often as you say would point to an error with that saw, many little places for air to leak in from the lean out the mix. Find out what he charges for a complete over haul replacing all gaskets, seals fuel lines and whatnot. Also check with other small engine guys around for there price, if its more then 2/3's to 3/4's the price of a new saw its your call on replacing it with a 461.
WD-40, DUCT TAPE, 024, 026, 362c-m, 041, homelite xl, JD 2510

joe_indi

Quote from: Randy88 on July 03, 2016, 09:31:02 PM
...............

As they say, nothing ever broke sitting on a shelf or wrapped in a case in the store waiting to be bought, it breaks while using it, either from wear and tear, abuse, neglect or a flat out brain fart moment and most knew better in the first place.     

The reason for the thread is.................I don't know and am wanting to know because beyond the finger pointing, its happened before, same ordeal, same scenario and when I took it in, he knows me well enough that I want answers as to What happened and after it was discovered, nothing seemed amiss, I looked it over the last go around and with the exception of a scored jug and piston, everything looked fine and all we came up with was, maybe a fluke, which isn't out of the ordinary in my life, with all the equipment I own and run, things do happen, things wear out and nobody is to blame but hours of use.   
............. 
This might be hard to believe but at times these small engines have problems because they were just sitting for a long time, maybe not a brand new one, but one which was run for some time and then left untouched. Carb components could suffer and lean out the fuel.
I am sure there is enough talent and knowledge on this forum to give you possibilities for your trouble, but things would definitely work better if we could see the damage, in some pictures.
Joe

Randy88

As for checking around with others on price for repairs, that's when that screw the customer kicks in big time and I'd never trust anything any of the rest would tell me, as they say been there done that, this dealer is the only one I'd trust in my area for anything.     

For a complete check over and install the new jug and piston is one price, and for about twice the price I can trade for a new saw.     

The only issue with that is................what do I need to know so once the warranty is off, I don't do the same thing to the next saw??   I absolutely had no clue anything was wrong with this one, after shut down it just wouldn't start or fire at all, I or we never saw any signs, symptoms of any sort, it never missed a beat while running, didn't sound differently, run faster, slower, lug down, lose power, anything.     


Gearbox

Do you run your saws out of gas or do you try to fuel them when they are low ? Trying to finish the last cut on a tank with a hot saw . May cause a lean score though I still would lean toward an air leak somewhere .
A bunch of chainsaws a BT6870 processer , TC 5 International track skidder and not near enough time

Texas-Jim

In all saws i know of are two seals on crankshaft, as well as most saws have rubber boots between the carb and the engine.  Those seals can and do fail just sitting on a shelf. If they start allowing air into the system it leans the saw out. That leaning builds up heat incredibly fast. The fuel itself keeps the engine cool as its running. A lot of causes like bad fuel can very hard to figure out. Some saws like the MS170 will start pulling air around the filter when it gets dirty, then the saw just eats all the dirt. That can cause failure as well over longer periods.

Many times its very hard to notice a difference in way an engine sounds. Saws as a rule live in a very harsh world, they are surrounded by dust, dirt, often bad fuel. And by bad i mean we as customers cant control quality of fuel  we buy. It amazes me some times they last as long as they do.

What we do in life echoes through eternity.

farmguy

Well when you have problems like that first thing I would do is look at the spark plug. It tells you how the saw was running. Almond brown is fine. Black is rich wich over time will cause exesve carbon wich can brake a ring on the exhaust side. Wite is lean. Lean causes the combustion to be too violent and produce exesive heat and engine speed. Also there is less lubricating oil for the speed of the engine so its a triple threat. You should change your plug once a year I have heard of spark plugs having the electrode fail and cause piston damage. People aren't necessarily playing the blame game but even at 200 hours if you do everything right the saw should be fine.i had a ms 290 for ten year and the piston looked almost new. I did however have a bearing start to give out I believe the plastic bearing cage let go so I traded it in

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