Guy's I have a Hanger 9 trainer. The exhaust oil is going through the vent tube into my tank... With fresh gas it runs great, until the fuel in the tank gets contaminated from the oil out of the muffler. The vent tube in the tank is set right..... What is going on?????Carl</p>

Hi Carl,

Need a bit more info to help you out. What sort of motor are you using. Is this a new problem or something that has developed over time?
A picture of the motor and plumbing would really help.

Cheers,

Colin

A brand new engine or a worn out old engine tend to blow out little ground up metal bits that seems to end up going through the pressure line into the fuel tank. I have never seen it so bad that the engine goes dead stick from it but what the heck, I have seen some odd things over the years. There is also a baffel plate in most mufflers, if that is loose inside your going to see a lot of gunk in the pressure line depending on where the pressure nipple is located. If you can you could try to see if it's tight enough or just remove it. If it's a new engine then it will go away by about the first gallon of fuel used. If it's an old engine wearing out then it will just get worse with use.

I've heard of guys using a filter between the muffler and the vent tube to filter out some of that crap. I've never done it, seems extreme. But I do like to have a filter between the tank and the carb. Some guys don't even like that. I had an issue where my fueling pump broke down and I started using my old Control line syringe to fill my tank. But the syringe was so old that the rubber piston had deteriorated and black rubber particles went into my tank and eventually clogged my filter. Two deadsticks later and I knew something was wrong. So any crap or crud can do you in.

Like he said!

I've never found a PTS nor 2 stroke Evolution engine where this did NOT happen.

The gray shavings will eat up your plugs too.

Consider letting the engine just run at mid throttle on the ground for 3-4 tank fulls.

This will get rid of most of the particulates that get shaved off.

Most of the particles seem to come from the rear of the crank shaft rubbing up against the back cover plate.

I wish Evolution would just insert a gasket or spacer in there to fix this problem.

It does go away by itself after the engine is run, but this should not be needed!

If it's an Evolution engine with the stock muffler, the gray gunk is probably being caused by the aluminum baffle disc in the muffler.
I would dis-assemble the muffler and and check...if that is the case, remove the disc...

Nope, that's not it.

We've verified that the gunk is not caused by the baffle.

You can substituted a different muffler without a baffle and still get the gunk.

I've done this.

What kind of "gunk" it is?

There shouldn't be much coming through the pressure line. Is the tap in the lower part of the muffler?

I didn't want to pick on Evo but it's true. They tend to blow a lot of worn crud as they break in. It seems to be the back plate for the most part but most engines when new or old do it. It's just a wear in or out process. I even have engines without any baffel and you can see the pressure line getting a little gray. Nothing to worry about but Evo seems to blow a lot more gray mater then other brands. It goes away with use as the engine breaks in. Other then a burnt out plug every now and then it's no big deal. You can use your pump to suck out the bottom of the tank. A filter tends to lower the tank pressure and you can have other problems then. A good clunck filter is a pretty good idea too, keeps all the nasty from going back through the engine.

Where in this thread did I miss where you "verified" that it is not caused by the baffle? I've seen more than a few Evo engines...have several of them myself...and the alum. baffle disc typically starts to vibrate and fret inside the muffler, causing a LOT of gray schmutz to come out the exh. and some of it gets into the pressure line.

On my .46's I quickly replaced the muffler w/ an Aquacraft/Tower .46 muffler and the gray goo stopped appearing.

I have no unusual wear patterns on the backplate either...?

Maybe I missed a previous thread by the O.P. where he said he'd removed a baffle or something?

It's not the baffle causing the grey gunk.

I've seen it on dozens of Evolution engines including a half dozen I own myself.

I've used baffleless Pitts style, and other muffler setups on brand new Evolution engines and all do the same thing.

Check out Greybeard's post as well.

If you pull the backplate on a relatively new engine, you'll see the wear the crankshaft produces on the backplate.

You'll also often see the same particulates on the inside of the engine, which are not being blown in by the muffler.

It is these particulates that make up the goo.

The baffle plate is made of a different material than the engine shell itself.


If you want reproduceable empirical evidence:

Burn a bit of the goo after cleaning in distilled water, and you'll see it's characteristic combustion color.

Burn a shaving or scraped bits from the engine shell, and you'll get the same color.

Burn a shaving from the baffle, and you'll get a different color.



You can remove the baffle on a brand new engine, and it still produces the gray goo in the same amounts.

I've done this too.

True...there will be a wear pattern on any engine's backplate...that is typical. I've seen in in virtually every engine I've disassembled... however...if that is the cause of the gray goo, then there is a more serious issue w/ the engine.

The Evo muffler is a lousy design...overly restrictive (too small an internal volume ) and the baffle disc will rattle around inside, causing the gray crap in the exhausted oil...I've wittnessed it many times...the best place for the stock Evo muffler is to leave it in the box it came in or in the trash. (JMO of course )

Now when you (opjose ) say that you can remove the baffle and still get "gray goo in the same amounts" do you mean enough to contaminate the fuel and to cause the engine to run badly or cause it to quit? Same question for a Pitts style or any other muffler?

I've never had that problem I will admit...in 35+ years of successfully operating glow engines...I've run many hundreds of them.

If the O.P. is getting enough gray stuff in his tank and it's not comming from the muffler, then there is something seriously wrong w/ his engine. It's possable it was crashed and the crank was pushed back and there is more than the normal light brushing of the rod on the backplate.

Hey guy thanks alot... The motor is a evolution .40   I pulled out the baffle and all is well... It is a brand new motor never flown yet.Carl

I normally run my engines with filters so I've not seen the goo contaminate the fuel from the tank.

The particulates are pretty fine, and I've seen them get on the plugs and burn them out quickly.

When newbies arrive with these engines, I find that after the first few tankfuls we need to change the plugs to prevent problems.

So YES I've directly experienced the goo burning out a plug causing the engine to quit while testing the engine of a newbie's plane.

I've also had the same problem when using Pitts style mufflers on brand new engines.


On a new Evolution engine there is a good amount of goo, during the first few flights.

This can be mitigated to an extent by running a few tank fulls of fuel through the engine while on the ground, then flushing the crankcase with glow fuel... ( I've purposely flooded the engines, and let them drain out again with the plug removed... ).

The "goo" is heavier than the glow fuel so it tends to pool to the bottom of the crankcase, muffler, tank or where-ever it may get into.


But that does not equate to an equal amount of Evolution engines does it?


You would then have to say that ALL Evolution two strokers have "something seriously wrong" with them, as they all do this... and it's not coming from the muffler... You can test for this as I have... nor am I the only person experiencing this problem using different mufflers.

Poor design? Not enough clearance? I dunno.

I've run new Evolutions with Pitts mufflers, baffle less mufflers, mufflers swiped from other engines, etc. and the problem persists.

After about 2 gallons or more of fuel run through the engine, the goo all but disappears. By about the third gallon it is no longer an issue at all.

Given that the PTS is sold as "broken in and ready to run" I guess it would be safe to say that it is a big problem indeed.


No other two stroke engine I've run has ever produced the amount of particulates that the Evolutions do....

After you get beyond the goo problem, and the limiter problems the engines run well... ( Exception: The 1.00 NX's... )



Of course pulling the baffle doesn't hurt in the least either, and produces a bit more power from the engine.

[8D]

Until the goo comes back!

The cheap rear bearing getting worn and allowing the crank to move fwd/rwd and rub the backplate could be what you are talking about?
That is another major factor with these engines.

I have 4 Evo's and have helped numerous beginners w/ various H9 aircraft equipped with Evo's (couple of dozen at least, to answer your (opjose's ) earlier question )
The rear bearings seem to wear and or corrode very quickly/easily. I've replaced many with bearings from either Boca or RC-Bearings.

I have an Alpha trainer with an evo 40 on it. At least it is not just me that had this problem. I also had the exhaust gasket disentigrate (sp?) and go into the tank. Hate to bad mouth them but i am never going to run an evo again. Now due to all the gunk I need to redo the bearings and everything. I actually think I am going to redo my Kadet senior and scrap off the alpha for parts.

But thank you for all the good advice on this motor. If I do decide to rebuild it I now know what to look for.

It's just a slight end play problem and yes the rear bearing does take the pressure and wear a bit quicker, the crank also rubs the back plate when it moves back. I have seen a lot of wearing problems with the Evos and noticed a lot of filed shavings getting into the tank. By removing the baffle or using a different muffler without a baffle {not even sure the Evos still have the removable baffle?} most of the ground up goop is blown out the exhaust and doesn't get into the tank. If enough of those nasty little shavings get to the top end they will short out the glow plug. I even get a lot of colored goop after i do a rebuild on an engine, just not very much!!