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Partially Stuck rings.Is such a 'jump start' possible

Started by joe_indi, March 21, 2013, 07:11:06 AM

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joe_indi

I had a customer's MS460 come in today with the complaint that it wouldnt start.Since I dont have compression tester I go by the sound of the engine without the plug.With throttle wide open when the engine is cranked I listen for the healthy sound that emits from the intake and exhaust, something similar to a 360degree twin cylinder bike engine( my opinion).
Well this saw did not have that distinctive sound, more of a flat empty noise.
So I checked the piston with the muffler cover off. No damage to the piston.But that slight movement of the rings when the piston is rocked up and down was missing, which led me to suspect that the rings were stuck in their grooves.
Flushing the engine with some fuel showed a higher than usual carbon / sediment level in the engine.
If I could get the engine to fire up a couple of times, it would free those rings.But my attempts to start up  did not work. I wanted to avoid lifting up the cylinder for this.So I sat back and thought out the whole situation.
The theoretical engine needed 3 things to get it going, fuel, air and spark.
Fuel I can arrange,   so also the spark, but, the air (compressed) was a bit in short supply due to the stuck rings.
Supplying more of the other too might compensate. Fuel you can supply a rich mix, but how could I increase the spark, or modify the timing?
Well, here is where a Chinese knock-off saw came to my aid. The spark plug on this saw is, I think is of an unsuppressed variety and therefore, very strong. Turning the flywheel over by hand is enough for it to throw a spark.
My assistant had once tried the spark plug of a Chinese saw on a MS460. Well his finger is still in splints because the MS460  backfired at the slowest pull on the starter. Strong and advanced spark.
Maybe what I needed in the present situation.
To cut this story shorter, with that Chinese plug fitted at the first pull on the starter, I got some smoke from the engine at both ends. At the second pull, more smoke from the exhaust and with some half hearted attempts to come to life. The third pull had the saw start off slowly like it was trying to clear itself off a  flooded insides. The fourth pull, nearly took my finger away, when I was sure those rings had freed themselves. So I fitted the original NGK plug, and sure enough, that saw fired up on the first attempt.
So, I would like my peers to tell me if it was the unsuppressed bigger spark or the advanced spark of the Chinese plug that worked for me.
Anyhow,I have given the owner of that Chinese saw a free NGK plug as a replacement, because I am hanging onto that Chinese spark plug for future use.
Joe

AdkStihl

Doubt it.
Sounds more like it was flooded.
Did you try a new BPMR7A? You could've opened the gap on a new NGK to provide a bigger arc. Not necessarily a stronger arc, but one with more surface area.

Now that you have filled the crankcase with fuel, I'm gonna bet you rinsed loose the crud (sediment) that likes to hide between the oil seals and outer face of the bearings. Something I wouldnt have done unless I was planning on replacing the crank and bearings.
J.Miller Photography

joe_indi

Quote from: AdkStihl on March 21, 2013, 08:10:38 AM
.........
Sounds more like it was flooded....................

Now that you have filled the crankcase with fuel, I'm gonna bet you rinsed loose the crud (sediment) that likes to hide between the oil seals and outer face of the bearings. Something I wouldnt have done unless I was planning on replacing the crank and bearings.

No it was not flooded.
I am yet to see a saw damaged from extra fuel in the crankcase.
If, the damage were to occur like you say, wouldnt every saw with a badly leaking inlet needle or damaged pump diaphragm be candidates for crankshaft and bearing replacement?
Joe

bandmiller2

Thanks Joe,sometimes the simple down home fixes will bail you out I always read your posts. Frank C.
A man armed with common sense is packing a big piece

Cat-Face Timber

Why not just pull the Cylinder and then you would know for sure what the Rings were doing?

SEMPER FI

Al_Smith

I've had them hung from laying around on a barn floor for two decades .Squirt some kroil in them and let them set a week .Blow the stuff out with compressed air and run them a tad and they purr like a kitten .

I've also had them fire early and nearly pull my fingers off which is exactly why most of my souped up saws have Stihl 460 rescue saw D-handles .

mmartone

I wonder what sort of plug you have there... The plug cannot advance the spark timing, no way no how. Could it have a hotter spark, possible, could it have a larger gap, sure it could. So what is it?
Remember, I only know what you guys teach me. Lt40 Manual 22hp KAwaSaki, Husky3120 60", 56" Panther CSM, 372xp, 345xp, Stihl 041, 031, blue homelite, poulans, 340

joe_indi

Quote from: Cat-Face Timber on March 21, 2013, 04:20:53 PM
Why not just pull the Cylinder and then you would know for sure what the Rings were doing?
I just wanted to try if there was an easier alternative to pulling the cylinder.

Quote from: mmartone on March 21, 2013, 11:14:26 PM
I wonder what sort of plug you have there... The plug cannot advance the spark timing, no way no how. Could it have a hotter spark, possible, could it have a larger gap, sure it could. So what is it?
This is the usual plug that comes on any Chinese grey market saw. The spark is very strong compared to regular plugs.But you cannot use them reliably  on a Stihl or Husky because they usually 'fade' when they are hot.
If the timing is not advanced even a wee bit, why does the saw backfire if you dont pull briskly enough? The same saw with an NGK BPMR7A or Bosch WSR6F would not do this.

Joe

Al_Smith

It will fire early because the cylinder is full of gasoline or at least the fumes .

Al_Smith

Some coils do not require such a great speed of rotation to fire .

I think it was last year down at Bill Poors GTG good old Fred ,AKA Stihlboy pulled my souped 038 Mag over the check the compression which it has a bunch .He rolled it over slow but had the mag hot .It likened to jerked his arm off .

You gotta remember a standard  Stihl is set for 27 degrees spark advance .If you pull it over slowly with the mag hot and not fast enough to get enough inertia to roll it over center it has a good chance of coming back on you .The higher the compression the harder it will kick you .Pull on that thing like you mean it ,never baby one on a start .

hamish

What kind of hack operation are you running?  No compression tester?

Let me guess no vac and pressure tester either?

Whats your shop rate?

A compression tester and a simple visual with prod of the rings would have taken 2 minutes, regardless the cylinder has to be pulled and the rings and ring lands cleaned up.
Norwood ML26, Jonsered 2152, Husqvarna 353, 346,555,372,576

beenthere

south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

Paul_H

Watch your tone Hamish or go away.  >:(

Joe is a member in good standing and knows his onions.
Science isn't meant to be trusted it's to be tested

Al_Smith

The big question is what caused the rings to stick in the first place?

joe_indi

Quote from: hamish on March 24, 2013, 04:54:43 PM
What kind of hack operation are you running?  No compression tester?

Let me guess no vac and pressure tester either?

Whats your shop rate?

A compression tester and a simple visual with prod of the rings would have taken 2 minutes, regardless the cylinder has to be pulled and the rings and ring lands cleaned up.
Ouch!That hurts.!
Hamish, I set up shop in the early 90s. Much before Stihl set up its own operations in my country(2004). In the late 90s a Dubai based firm did function as a dealer till 2002.
So, when I started off it was with a rich inventory of tools such as a couple of screw drivers, spanners, pliers and some other tools that I used for DIY jobs on my motorcycle.
I was technically qualified to work in a kitchen. The engine repair bit was self learned from age 10. So, a great deal of requirements for testing tools were met by visual and audible methods (and olfactory   :D)
Though you might find this hard to believe or accept, there was a time when I was the only retailer in my country offering complete repairs for the saws that I sold.
This I was able to do mainly due to several 'shortcuts' I was forced to adopt  due to many tools and test equipment not being available locally.
Test equipment is available now and I do have most of it (except a compression tester). But I rarely use them because I am happier with my 'unorthodox' methods.
And, if you really need my 'Shop Rate' just why dont you find it out yourself?
Go to www.stihl.com and post a message there or, navigate a step further  to  the Stihl India site and post your message there.
You will then know more about my hack shop.

Quote from: Al_Smith on March 24, 2013, 07:12:39 PM
The big question is what caused the rings to stick in the first place?
Al, 90% of the saws here are run with badly filed chains.They spend more time lowering the rakers than on the cutters.
The result is no chips instead of which its fine saw dust mixed with rubber latex that passes easily through the mesh of the air filter.
This dust:latex forms part of the fuel mix and travels everywhere inside the engine, till it is finally burned in the combustion chamber.Some of this after the burning gets trapped in the rings' grooves in line with the exhaust port.
This sticking is enough to prevent vacuum or compression in the engine.
A fast cure is flushing out the engine with some fuel (about 3 oz each time).
At times the rings still remain stuck so that I have to lift the cylinder to get them free.
When you have 4 or 5 saws come in together from different work sites with the same problem and you are running a small shop with only one assistant, you have a problem because the customers might be in the middle of their jobs with trucks not completely loaded.They need to get back fast to finish the job.So getting the saws up and  working as fast as possible is the priority, not how it is done.

Joe






beenthere

Joe
I've been real impressed with your knowledge of the chainsaws and the very helpful sharing of your Stihl knowledge and resources of same.
Thanks for your update on your very humble beginnings.
Keep up the good work.
You are a great FF member, IMO.
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

joe_indi


Al_Smith

Oh that would do it allright .Dust mixed with rubber sap would be akin to sand mixed with axle grease .

More than likely the sticking rings would cause some blow by and coke up the bearings with pyralited oil coke .What a  mess .

Paul_H

Great post Joe and I agree with Beenthere wholeheartedly.
Science isn't meant to be trusted it's to be tested

JohnG28

Quote from: beenthere on March 25, 2013, 12:12:43 AM
Joe
I've been real impressed with your knowledge of the chainsaws and the very helpful sharing of your Stihl knowledge and resources of same.
Thanks for your update on your very humble beginnings.
Keep up the good work.
You are a great FF member, IMO.

I completely agree. I have learned much from Joe as well and really appreciate all his input.
Stihl MS361, 460 & 200T, Jonsered 490, Jonsereds 90, Husky 350 & 142, Homelite XL and Super XL

joe_indi

Thank you for the appreciation.
Though its not much  maybe you could help yourselves to some of these

Joe
:laugh:



clww

Joe- I think your knowledge shown through your posts is very impressive, too. :)
Many Stihl Saws-16"-60"
"Go Ask The Other Master Chief"
18-Wheeler Driver

Cedar Savage

I'm with Joe, If it works, it works.
An old timer that owned a Jred shop showed me a trick, some times when the rings get carbon'd up, you can dump a couple oz of brake fluid in the piston, an the plug reinserted. Then flip the saw upside down over night.  Next day, pull the plug, & drain, rinse with a shot of ether or something. Put a new plug in & fire it up, 75% of the time it works, & will free up the rings. 
"They fried the fish with bacon and were astonished, for no fish had ever seemed so delicious before."         Mark Twain

NCFarmboy

25 or so years ago my saw shop guy (Carl) showed me a trick to get em going by putting mixiing oil in the cyl. (enough to go around the ring) pull starter, (plug out) to coat everything.  Put plug back and start.  The oil being thicker gives a better seal around ring hence more compression.  My Dad had a 44 Husky that had sat in the barn for 15 or more years after he died.  I pulled on it til I was good and mad remembered Carl's trick put some mix oil in it.  Started on second pull been running like the little banshee it is ever since.  Works for lawn mowers too.
Shep
Lots & Lots of Saws

SPIKER

I would be very wary of using the Brake Fluid as it is kind of caustic (it will remove paint too.)   ATF (Automatic Trans Fluid) works GREAT and as will the Mix Oil, though not as "cleaning" as the ATF.   ATF will also remove Varnish and Carbon real well & has been used prior to most of the fuel system cleaners.   One other thing which would be a bit more costly would be to use Lucas or Sea Foam though not sure how well that would work on the Rubber Tree GUM inside your saws.

On a side note if you have some PLASTIC (say model car or chainsaw case) that someone PAINTED soak it in Brake Fluid and the paint will bubble up and can be wiped off.   It will not NORMALLY affect plastic (swelling may happen so please test on something hidden 1st.)

Mark
I'm looking for help all the shrinks have given up on me :o

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