Trimmer Blowing out rubber pieces

[Mini Motors]

No such thing as "soft carbon".

 

[Lawnranger]

No such thing as "soft carbon".

What do you base your statement on?

 

[PaulRevere2012]

Ok, I broke down the engine and I found the source of the "latex" It appears to be a gasket on the cylinder head. See pic. Forgive my ignorance as I've never broke down an engine beyond the carb but is this a gasket you buy or is it one which is self made with some "liquid" gasket material?

https://skydrive.live.com/?cid=315ABB62A0C122D1&id=315ABB62A0C122D1!176

 

[exotion]

Wow that thing looks beat to hell :/ at the very least once you figure out the gasket thing you have it already taken apart clean everything make sure no metal on the inside is scarred make sure the piston also has no scarring and make sure you have everything torqued correctly when you put it all back to gether

 

[PaulRevere2012]

Wow that thing looks beat to hell :/ at the very least once you figure out the gasket thing you have it already taken apart clean everything make sure no metal on the inside is scarred make sure the piston also has no scarring and make sure you have everything torqued correctly when you put it all back to gether

Yeah, the gasket was completely destroyed. How that happened, I have no idea. Anyhow, I took the cover to a local auto store and they said that it was Black RTV silicone instant gasket. I got some and will place a bead around the cover. I need to get a couple of piston rings first because one of them broke.

 

[Mini Motors]

What do you base your statement on?

Carbon is a very hard substance that is sometimes used as brushes for electric motors or generators. When it forms inside an engine cylinder, it happens because of the intense heat in an air cooled engine. And even more so in a two stroke, because of the added oil. It can build up so much, and when it does chip off, it usually just gets swept out the exhaust. But sometimes it can get caught in between the piston and cylinder wall, and put quite a nasty scratch the cylinder wall. And that equates to it being harder than steel.

 

[Lawnranger]

Carbon is a very hard substance that is sometimes used as brushes for electric motors or generators. When it forms inside an engine cylinder, it happens because of the intense heat in an air cooled engine. And even more so in a two stroke, because of the added oil. It can build up so much, and when it does chip off, it usually just gets swept out the exhaust. But sometimes it can get caught in between the piston and cylinder wall, and put quite a nasty scratch the cylinder wall. And that equates to it being harder than steel.

The reason I ask is because of my previous experience. Gasoline has gone through many changes over the years and if I said "gasoline isn't what it used to be" I believe many people would agree with me. If we take a look at the history of gasoline we find that lead used to be added to gasoline to help boost octane and as a side benefit it would lubricate the valves. U.S. EPA laws mandated that lead be removed from gasoline due to the toxicity level increase in our atmosphere. This change happened some time in the mid 1970's and since then many more changes have taken place such as MTBE (Methyl Tertiary Butyl Ether), Ethanol, etc.

In years past, about 25% of a barrel of crude oil would be made into gasoline but now the percentage is over 60% (and I've heard up to 80% but can't verify) and that translates to more of the heavier & lighter fractions of crude oil become gasoline in which they must be formulated to stay mixed. As a result of these changes the carbon deposits we are familiar with have changed over the years. In the 1960's & 1970's the carbon deposit on intake valves was actually a softer deposit that could be easily removed during a valve job and some of the older mechanics on this forum probably remember what I'm referring to. I worked with a mechanic that performed "hillbilly tune ups" in which he would get the car out on the freeway and accelerate as hard as he could. Lots of black smoke poured out the exhaust in which some was due to a rich condition but some was also soft carbon literally being blown off the valves, piston crown and combustion chamber. An old excuse given to police officers as to why a driver was speeding or accelerating so hard was: "honest officer, I was just blowing the carbon out". The excuse rarely, if ever, worked and the driver got a much-deserved ticket however the practice was successful in removing soft carbon deposits. In recent years if you wanted to remove deposits from an intake valve manually you most likely use a bench grinder with a wire wheel and would have to push much harder to remove the deposit compared to decades ago.

Carbon itself has not changed but what has changed are the other by-products that bond carbon molecules together and this is the reason we no longer have soft carbon deposits. Another contributing factor is that engine operating temperatures have increased over the years and this bakes the carbon on even more. For instance, the temperature where the cooling fan turns on in some cases is 235 degrees.

I do agree that brushes for electric motors have carbon in them but they also need a bonding agent to hold the carbon in place. However if carbon got between the cylinder and piston, as you say, we would see just about every engine out there with scored pistons/cylinders. What I believe happens is the two stroke engines are run too lean and get too hot or lack of proper lubrication which causes metal transfer and since the cylinder wall (steel) is harder than the piston (aluminum) we see scored pistons. Carbon is definitely a hard substance but the bonding agent would break under the pressure of being squeezed between the piston and cylinder and if it didn't we would see many more engines with carbon scoring or scratches in the cylinder and/or piston - thankfully we don't have that problem.

Fortunately there are some good products on the market that will remove carbon deposits safely and quickly. Polyeither amine is one of the known best products to do the job safely and effectively by dissolving the bonding agent that holds carbon molecules together and allowing the carbon to exit the exhaust system in such small particles that they cannot be seen by the naked eye. Polyeither amine is found in products such as BG 44K and Chevron Techron. Of the two products mentioned, BG 44K has a greater concentration of Polyeither amine and will achieve the desired result sooner. No, I don't work for either company or even a chemical producing company, I've learned some things along the way and wanted to share them. Thanks for listening.

 

[Mini Motors]

Back in the day(60s, early 70s) my Dad made this "cocktail", the only two ingredients I remember are MMO, and denatured alcohol. He'd pour it down the carb, just before the point it would stall, twice, and the third time he'd stall it out, all the time just pummeling the neighborhood with thick blue smoke. He'd give it an hour or so, and take it out for a spin, just to "blow the carbon out".

But there has never been anything that will soften carbon. Just loosen it. And therein lies the danger. Thankfully, most all of it gets blown out the exhaust. Metallurgy has improved somewhat over the years, so the cylinder(s) have a better chance at survival. You're right, in that heat plays a significant part in carbon formation, particularly in our air cooled motors, and even more so in two strokes. I would think cars run cooler, with all that computer and sensors, but certainly more precise.

I love BG. They make a great transmission additive, too. I use Seafoam in all my small engines. I don't know if it has Polyeither amine in it or not. But my motors are clean inside.

 

[mhall96162]

Thank you, thank you, thank you. Same thing just happened with my Husqvarna 223L. So far, I had taken everything apart except the cylinder head. The Husqvarna National "help line" had no suggestions. I took the "chunks" to a local authorized Husqvarna repair shop and they were baffled. Then one mechanic said another local repair shop had the same rubber in his Husqvarna. but he didn't know if the other repair shop ever found the source. Since my air filter, fuel lines, all parts of the carb., all gaskets (except now I know to check the cylinder gasket), fuel tank, fuel filter, clean fuel/good oil, (treated with Ethanol Shield) --- all checked out "fine", I thought I was going nuts!!! Tomorrow I get back to work on the cylinder head. Thanks again. I need to call the local dealers and tell them. mhall96162