Jump to content

Unofficial Home of Old Simplicity & Allis-Chalmers Garden Tractors

Carbon Build-Up - Minimizing It???


Recommended Posts

My boys and I have my Agco 918H in our sights as we try to get it going this Spring. As I posted a while back, while replacing the head gaskets on the Kohler Command CH18 engine, I snapped a few tin screws and was scared to death I would going to snap one of the head bolts!

I know decarbing an engine is an essential service, but how can you minimize the build-up in the first place?

I know there is lot of stuff you can pour in the gas, spray in the carb, etc., to reduce or eliminate carbon build-up. What do you recommend? Have you looked at a badly carboned engine (with head off), re-assembled, added gas treatment or sprayed into the carb the same and then taken apart to see the results?

Any tips, tricks, advice would be appreciated.



Link to comment
Share on other sites

I myself LOVE sea foam to help remove and reduce carbon buildup in all of my tractor and boat engines. I have used this stuff for 26 years with great success. JMO

Link to comment
Share on other sites

X2 on the Sea Foam additive suggestion. I add an ounce per gallon to my fuel for use as both a stabilizer and as an Ethanol treatment, as well as using it twice a year to decarbonize the piston and valves. You can add a few ounces directly into the carburetor intake with the engine running (add it slowly or it will bog the engine and choke it out), then turn it off and let it sit for 5 or 10 mins before starting it up again.

I typically just pull the spark plug out and add a few ounces directly into the spark plug hole and let is sit for 10 mins or so to break up the carbon, then put the plug back in and fire it up.

DO IT OUTSIDE, AND STAY UPWIND - it will be a smoke dragon !!! It will bilge a huge amount of white smoke for 5 or 10 mins before the exhaust slowly begins to clear, which is the dissolved carbon being burnt off.

Good fun, and good for your engine !!

Link to comment
Share on other sites

------I myself LOVE sea foam --------

I'll third that. Since I started using sea foam I haven't need to touch a carb on these machines. 3314 and 725 sit all winter, fires right up in the spring, B-112 sits all summer and it's ready for snow in the winter. Think it's been about 5 years now I been using it.

Forgot, Rislone poured through the carb works Great for carbon removal. I overhauled a 16hp briggs I bought cheap that way because of the bad knock in it. Stills running today.

Link to comment
Share on other sites

I generally do not treat fuel with anything, except the diesel fuel in my EF1D to prevent jelling in winter.

I have removed carbon from several engines over the past 30 years by using auto transmission fluid. I warm the engine up to full operating temperature first, then with the engine at full throttle, will will slowly pour the tranny fluid into the carb intake to prevent the engine from choking out. When the cold tranny fluid hits the hot carbon on the head, the carbon will cool quickly and pop loose from the head. You will then start seeing small pieces of black carbon coming out the exhaust along with the smoke from the tranny fluid being burned.

It only takes a few ounce of fluid, because the goal is to cool the hot carbon quickly and make it break loose from the head.

I have never had a need to remove carbon from any of my small engines that I was using myself. I have only had to de-carbon engines when I first got them from someone else.

Also most of the really thick carbon buildups actually are produced by having the carburator adjusted too rich. If the carb is kept properly adjusted, you may never have to do any special carbon removal. Carb adjustment is very easy, but for some reason, the average person does not usually know how to do it. Also the newer engines built since the 90s are not even adjustable, so they can have more problems with carbon buildups than the older ones.

In most cases, you can pull a spark plug out of your engine and it will give an indication of whether the engine is carboning up. If the electrode on the plug is a light to medium brown color, then the engine is burning relatively clean. If the spark plug electrode is black, then the engine is developing carbon in the combustion chamber. To check the plug you need to operate the machine for 10 to 15 minutes at WOT and then shut it down at WOT. This should be done while mowing tilling, plowing snow, or something that is loading the engine. Do not drop the engine speed to idle, because that is a different metering circuit which is usually richer than the full throttle setting and will blacken the plug very quickly.

Link to comment
Share on other sites

I use the same method as Rod above, except I don't use tranny fluid. I use dish soap and water in a spray bottle. Spray as fast as you can without killing the engine.

Basically steam cleans the inside of the engine.

It do stink and smoke though :D:D

Link to comment
Share on other sites

Sorry I don't remember the name, but i buy the bottle of solvent that takes most of the ethanol out of it. Because these older machines weren't built for ethanol. They were built for the Leaded Gas. It's about $3, and you only use a very little. It's about the same size of a dry-gas bottle.

Link to comment
Share on other sites

Sorry Ryan, guess you are not old enough to know about it, but B/S has always recommended using unleaded gas in their engines, even back in the 50s and 60s when I was a kid. Back then Amoco was selling unleaded gas.

Alcohol is not the primary carbon producer in the engines, gasoline is. In fact alcohol burns cleaner and produces less carbon than gasoline.

There are several other problems with alcohol though:

1. Alcohol contains only about 1/2 the energy by volume that gasoline does - creating a little less power with the 10 percent alcohol.

2. Alcohol is actually a cleaning agent and causes deposits inside the fuel system to break loose and sometimes clog jets.

3. Alcohol can react with the metal in the carbs and cause major corrosion if left in there for a long time and allowed to evaporate. I have seen carbs where the float mounts were completely eaten away by the alcohol in the fuel.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...