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Gasser Model RC Helicopters > How do you remove carbon build up in muffler?
 
 
Mark222
Senior Heliman
Location: Kelowna, B.C. Canada

Finally figured out why my Benzin wouldn't make power. The muffler is getting bunged up with carbon deposits. I installed a spare muffler to confirm my theory and sure enough that was the problem. The Benzin was pulling strong again, had to tame down the throttle curve.

I boiled the muffler for 24 hrs in antifreeze but all that did was soften some of the carbon. The muffler is stainless with multichambered construction and the inner chambers are inaccessable for scraping or wiping. What is needed is something to dissolve or liquify the carbon so it can be flushed out. Right now I have it soaking in oven cleaner but it doesn't look like a sure thing either.

Anybody have a decarbonizing method that works?

Thanks,

Mark G
09-16-2003 Over year old.
HOMEPAGE  
 
 
gyan
Key Veteran
Location: Surrey, BC Canada

Carbon is tough. The only way I know how to is if it's a 2 piece to go to a body shop that has a sand blaster, protect all surfaces with aluminum tape that you don't want marred & blast it off.
09-16-2003 Over year old.
 
 
Manx
Heliman
Location: Adelaide, South Australia

In 1/5 scale R/C cars that use the same engines, we just plug up one end of the muffler, then fill the muffler with 'paint stripper', plug the other end of the muffler.

Leave the 'paint stripper' in there for a while, then remove plugs and flush out with tap water.

Warning, don't do this in the kitchen sink as the 'other half' (she who shall be obeyed) will have your googlies on a hot plate.

You'll be quite surprised at the 'gunk' that comes out of your muffler.

Cheers
09-16-2003 Over year old.
 
 
Mark222
Senior Heliman
Location: Kelowna, B.C. Canada

gyan:

I am very familiar with sand blasting, in this case it would not work because the welded construction prevents access to the inner chambers. Sand blasting is very agressive and could cause damage to the thin walled mufflers we use.

Manx:

Paint stripper!

I'll give that a try. Looking forward to flushing the "gunk" out of that muffler. This will have to become another regular maintenance item to add to the list.

What sort of end plugs do you use that stand up to the "paint stripper"?

Thanks for the warning on the "googlies" Reminds me to get the antifreeze off of the kitchen stove!!

Mark
09-16-2003 Over year old.
HOMEPAGE  
 
 
gyan
Key Veteran
Location: Surrey, BC Canada

Mark;
If your familiar with sand blasting you must know there are many different mediums to use, such as walnut shell, plastic bead ect, these are not as aggressive even aluminum pistons can be done without any damage to ring lands or anything, just watch the pressure. A welded muffler is another story.
09-17-2003 Over year old.
 
 
ImRich
Veteran
Location: Derry, NH USA

Mark,

If you find something that works well, let us know!!

---
Rich
09-18-2003 Over year old.
HOMEPAGE  
 
 
Mark222
Senior Heliman
Location: Kelowna, B.C. Canada

Muffler and the header pipe have been filled with paint stripper. The holes were plugged with tapered hardwood plugs, they have been soaking for 60 hours. This morning, hard carbon in the header inlet side has loosened up, it needed a light poke with a screwdriver to get it to flake off.
The muffler is still soaking, it had an air pocket inside so I've turned it to make sure all surfaces get a good soaking with the stripper. Later today I will drain out the stripper and let you know how it worked on the softer carbon.

Mark
09-19-2003 Over year old.
HOMEPAGE  
 
 
Naomi
Elite Veteran
Location: Ontario, Canada

Mark, could it be the oil ratio you used a bit heavier, caused the build up of carbon inside the muffler chamber

Naomi
09-19-2003 Over year old.
HOMEPAGE  
 
 
Mark222
Senior Heliman
Location: Kelowna, B.C. Canada

Naomi:

In reviewing my log book, the symptoms ( less power and a change in the exhaust sound ) started to appear when I was running a 90:1 Amsoil mix, this was after about 130 - 140 flights. The 90:1 mix was not enough lubrication for the crankshaft, as the wear on the crank "at the upper crank bearing" took out the crank seal. Since the repairs from that incident I've been running the Amsoil at 65:1.

I think the header and muffler need to be "decarboned" on a regular schedule, early enough so the carbon doesn't get too hard or too thick. When you see a carbon buildup inside the muffler outlet would be a good time to clean it, maybe 10 -15 hours of flight time.

Manx: Paint Stripper tip.

I drained the paint stripper from the muffler tonight after 72 hours of soaking. Lots of dark brown goo poured out along with many small chunks and flakes of carbon. I flushed it with hot water and shook it several times, each time I flush more stuff comes out. Now the header and the muffler are soaking in hot water ( with a little dish soap added ) simmering on the stove over night to make sure all the paint stripper is washed out. Will report tommorrow on how that goes.

In the future I think it might be worth hot tanking the exhaust parts at the local auto engine rebuilders, they can easily get rid of the carbon if it is not the hard stuff.

later,

Mark
09-20-2003 Over year old.
HOMEPAGE  
 
 
Naomi
Elite Veteran
Location: Ontario, Canada

Hi Mark,
I ran mine about 80:1 now.. piston getting pretty shiny. now after a mishap.. I have to replace the cranshaft. Is the front bearing easy to find in a bearing shop?.. I might go with ceramic one if i can find one. Also I thought you ran the tune pipe in your benzin. not the same type like I have.

Naomi
09-20-2003 Over year old.
HOMEPAGE  
 
 
Mark222
Senior Heliman
Location: Kelowna, B.C. Canada

Naomi,

Take the bearing to the bearing shop, see if they can either match it up or order one for you. Why do you have to change the crank? Was it damaged in your last "Terra Firma" or did it wear like mine did from insufficient oil?

The muffler I use is the 116/99, I don't know if it is a tuned pipe as such, but it does make more power than the stock Benzin muffler.

Update on carbon removal:

Lots of carbon came out with the paint stripper but the pipe is still restricted somewhere inside. Looking in the end with a flashlight I can see some hard lumps of carbon adhered to the inner surfaces. The stripper cleaned out the soft carbon and softened some of the hard carbon but did not dissolve the harder material. I'm not sure what the next step will be in this process. I really don't want to buy another pipe at $270 Canadian, when ever the muffler needs to be decarboned!
09-22-2003 Over year old.
HOMEPAGE  
 
 
Naomi
Elite Veteran
Location: Ontario, Canada

Hi Mark,
Well after I just rebuilt this time had about 3 tanks..comes down on a hard landing on the belly .. bent the crank , amazingly all blades are ok just the boom and shafts and canopy , but I have some parts so not too bad.. just need a few things to get it together again.. I had to pull the engine apart to replace the crankshaft. anyway. my muffler need to be replaced soon too anyway.. been using Jb weld to hold a few cracked area.. Rick has it for a pretty decent price.. http://www.ronlund.com/Merchant2/me...ode=Muffler_Gas $129.90. + shipping still less than $270 canadian after all the conversion. Is this the same one you'd been talking about?

Naomi
09-22-2003 Over year old.
HOMEPAGE  
 
 
Mark222
Senior Heliman
Location: Kelowna, B.C. Canada

Hi Naomi,

Thanks for the price on the muffler but it's not what I run. Check my homepage and click on "How it works", there is a picture of the pipe on the heli.

If a new pipe is needed, I might try one of the Desert aircraft pipes that Bill Meador likes to run.
09-22-2003 Over year old.
HOMEPAGE  
 
 
Naomi
Elite Veteran
Location: Ontario, Canada

http://sitewavesonline.net/Merchant...t_Code=116%2F99

Ok I see you ran the tune pipe not muffler.. mine is the one that shows on Ricks site. can you ran the same type I am running on mine? it's cheaper, power wise not bad either. maybe just me.

Naomi
09-22-2003 Over year old.
HOMEPAGE  
 
 
Manx
Heliman
Location: Adelaide, South Australia

Mark,
Glad to see you got some of the gunk out, When I have done it with my pipes, they come out sparking inside after the procedure.

I have been searching the web for the page where I originally found the article on this subject. I have not been able to find it at all, it was somwhere in the UK if my memory serves me correctly.

I do remember the author mentioning something about a 'thin viscosity' version of paint stripper that would flow easily into all the 'nooks & crannies' inside the pipe.

I use plastic protective plugs that come fitted on Mil-Spec electrical connectors to seal up the openings in my pipes.

I dont think I have helped you any further on this subject tho. You appear to have covered all the bases so far. Maybe another try with fresh paint stripper to get the 'stubborn' crud out.

Peter
09-22-2003 Over year old.
 
 
Manx
Heliman
Location: Adelaide, South Australia

Mark,
I have just remembered another product that may help, but you may have trouble finding it.

When I used to work on aircraft (1:1), the engine fitters used a substance called 'Carbosol' to clean the stainless steel augmentors (Caribou A/C exhaust pipes).

It is a very "nasty" chemical, they had to use full protective clothing while using the Carbosol bath.

The bath was full of Carbosol and had 'ping-pong' balls floating all over the top of the chemical to minimise splashing, then the lid was closed.

A word of warning, don't leave Aluminium in there for very long, you wont have anything left to retreive if you do leave it in to long ... LoL

Peter
09-22-2003 Over year old.
 
 
Manx
Heliman
Location: Adelaide, South Australia

Mark,
Cleaning the exhaust pipe on a moped or motorcycle with a 2 stroke engine
--------------------------------------------------------------------------------

*Warning: this is extremely dangerous do not trying this unless you are an accomplished torch person.
--------------------------------------------------------------------------------

The oil burned with the fuel in a two cycle engine leaves carbon deposits inside the muffler area. These deposits can be very thick, and cause the muffler to be completely shut in some cases. There are no safe solvents that I know of to remove these carbon buildups.
If only the tip of the muffler is plugged, pick it out with a long thin screwdriver or drill bit.
If the carbon is inside the baffle units, it can only be removed by cutting the muffler in two with a hacksaw, cleaning it and welding it back together.
The other method is using an acetylene torch. The torch method produces a large amount of smoke and pollution when done, so I cannot recommend it. It is also easy to overheat the inside of the muffler, burning out baffles and possibly burning a hole through the muffler. I suggest not trying this unless you are an accomplished torch person with a death wish.
--------------------------------------------------------------------------------
* But here is how you do it.
--------------------------------------------------------------------------------

Remove the muffler from the moped and lay it down on the ground, as it will get red hot and shoot out sparks several feet, so make sure you are not around anything flammable. Do not do this indoors!
Using the torch, and a small/ medium tip, put the flame very close, but not into, the tip of the muffler. after a few seconds, the tip should be getting red hot. Be careful not to melt the muffler tip.
Keeping the torch tip very close to the muffler tip, pointing the flame inside the muffler, turn off the acetylene knob so the flame goes out, and turn up the oxygen knob to increase flow into the muffler. This will cause the carbon heated with the flame to burn up, and you can regulate the speed of the burn according to how much you increase the flow of the oxygen.
To much oxygen pressure and you will melt your muffler into a puddle, so be patient. A red hot band will slowly move along the muffler, slowing down in the very thick areas, and the red hot area will go away when the muffler is clean.
If a lot of globs of molten metal come flying out, you are getting it too hot!
It is possible to get it too cold and the flame front will go out, so the best results come when you heat it so there is a good red spot, then slow a bit then heat it up again every minute or so. You must not stop flowing oxygen until the muffler is completely cleaned out, or you will need to restart it again with a flame.
If a muffler goes out, it can be hard to get the flame burning again since the carbon closest to the tip will have been cleaned off first. In this case, you may need to punch a hole in the side of the muffler to get a fresh start, then weld it shut when you are finished.
--------------------------------------------------------------------------------

Some mufflers cannot be cleaned in this way, a sound deadening material inside will melt into glass marbles, and they will plug the muffler tip from the inside untill you cut it in half to remove them. So, you may as well cut in half at the beginning and get it over with. Yamaha mufflers are notorious for this melted packing, for sure the Razz, Zuma and Jog. Most honda mufflers, like the Spree, Elite, Express, and pa50 respond well to this treatment.
The exhaust port is also a place to look for carbon buildup. You should be able to look into the exhaust port with the muffler removed and see the piston. The light coating of carbon that lines the port is not the carbon to be concerned with.
If there is a buildup, it will be right next to the piston, and in fact acting as a part of the cylinder, so the hole the piston is seen through is much smaller than the hole at the end of the port the muffler is mounted to. It is possible for an exhaust port that should be a 1" diameter all the way to the piston be reduced in size to 1/4". Most times this carbon can be removed by chipping it away with a small screwdriver or file, being carefull not to scratch the piston.
09-22-2003 Over year old.
 
 
Manx
Heliman
Location: Adelaide, South Australia

Mark,
A post I found on the net ... hehe.


Cleaning the exhaust pipe on a moped or motorcycle with a 2 stroke engine
--------------------------------------------------------------------------------

*Warning: this is extremely dangerous do not trying this unless you are an accomplished torch person.
--------------------------------------------------------------------------------

The oil burned with the fuel in a two cycle engine leaves carbon deposits inside the muffler area. These deposits can be very thick, and cause the muffler to be completely shut in some cases. There are no safe solvents that I know of to remove these carbon buildups.
If only the tip of the muffler is plugged, pick it out with a long thin screwdriver or drill bit.
If the carbon is inside the baffle units, it can only be removed by cutting the muffler in two with a hacksaw, cleaning it and welding it back together.
The other method is using an acetylene torch. The torch method produces a large amount of smoke and pollution when done, so I cannot recommend it. It is also easy to overheat the inside of the muffler, burning out baffles and possibly burning a hole through the muffler. I suggest not trying this unless you are an accomplished torch person with a death wish.
--------------------------------------------------------------------------------
* But here is how you do it.
--------------------------------------------------------------------------------

Remove the muffler from the moped and lay it down on the ground, as it will get red hot and shoot out sparks several feet, so make sure you are not around anything flammable. Do not do this indoors!
Using the torch, and a small/ medium tip, put the flame very close, but not into, the tip of the muffler. after a few seconds, the tip should be getting red hot. Be careful not to melt the muffler tip.
Keeping the torch tip very close to the muffler tip, pointing the flame inside the muffler, turn off the acetylene knob so the flame goes out, and turn up the oxygen knob to increase flow into the muffler. This will cause the carbon heated with the flame to burn up, and you can regulate the speed of the burn according to how much you increase the flow of the oxygen.
To much oxygen pressure and you will melt your muffler into a puddle, so be patient. A red hot band will slowly move along the muffler, slowing down in the very thick areas, and the red hot area will go away when the muffler is clean.
If a lot of globs of molten metal come flying out, you are getting it too hot!
It is possible to get it too cold and the flame front will go out, so the best results come when you heat it so there is a good red spot, then slow a bit then heat it up again every minute or so. You must not stop flowing oxygen until the muffler is completely cleaned out, or you will need to restart it again with a flame.
If a muffler goes out, it can be hard to get the flame burning again since the carbon closest to the tip will have been cleaned off first. In this case, you may need to punch a hole in the side of the muffler to get a fresh start, then weld it shut when you are finished.
--------------------------------------------------------------------------------

Some mufflers cannot be cleaned in this way, a sound deadening material inside will melt into glass marbles, and they will plug the muffler tip from the inside untill you cut it in half to remove them. So, you may as well cut in half at the beginning and get it over with. Yamaha mufflers are notorious for this melted packing, for sure the Razz, Zuma and Jog. Most honda mufflers, like the Spree, Elite, Express, and pa50 respond well to this treatment.
The exhaust port is also a place to look for carbon buildup. You should be able to look into the exhaust port with the muffler removed and see the piston. The light coating of carbon that lines the port is not the carbon to be concerned with.
If there is a buildup, it will be right next to the piston, and in fact acting as a part of the cylinder, so the hole the piston is seen through is much smaller than the hole at the end of the port the muffler is mounted to. It is possible for an exhaust port that should be a 1" diameter all the way to the piston be reduced in size to 1/4". Most times this carbon can be removed by chipping it away with a small screwdriver or file, being carefull not to scratch the piston.
09-22-2003 Over year old.
 
 
Mark222
Senior Heliman
Location: Kelowna, B.C. Canada

Naomi,

I would prefer to stay with the pipe configuration if I can. These things should not be disposable! Thanks for the link to the other style option.

Manx,

Wow! This is starting to look like rocket science!!

After being evacuated due to forest fires around our city , I don't want to play roulett with a torch. We've had enough flames threatening us for about three weeks. First time I've seen 400 foot high flames "Scarey stuff". We've had some rain so things have settled down a lot.

Another treatment with the paint stripper is probably the best route to go at this time.

Thanks for the tip on the "Carbosol" perhaps I can find a place that has a tank.

Thanks,
Mark:
09-23-2003 Over year old.
HOMEPAGE  
 
 
Xcellgasman
Heliman
Location: United Kingdom

I have just cleaned through my muffler on X-cell gasser (the M.A. Zimmerman type mounted on the rear).
Mine was getting fairly choked up and I got fantastic results doing the following:
Heat up the whole muffler evenly with a blow torch until smoke stops appearing from the inlet/outlet, this will burn off the oily crap.
I then bunged up one end with a cork and poured a very strong mix of caustic soda and water inside. I left it for 20 minutes and poured out the thickest filthiest sludge around. I did exactly the same one more time and flushed it all out with a hose pipe. It took 2 or 3 minutes for the water to run clean!
You can see into the muffler now and the walls are clean and shiny like new.
I am sure this is the easiest way to do it, but don't do it with alloy mufflers as you will not have a muffler left at the end
The zimmermans are a combination of stainless and mild steel I think, and will not be affected by caustic at all.
Hope this helps someone..
09-29-2003 Over year old.
 
 
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