decarb method/products/additives

[SCO]

This is about a '95 johnson 130 that has been running without thermostats. Is OMC engine tuner poured into the cyls overnight a good way to do this? I have also heard of gas additives that will do more than just prevent additional buildup. What is the best way to remove the built up carbon?

 

[12Footer]

Re: decarb method/products/additives

Flood the warm engine out using the product of your choice, and let it sit overnight.<br />Have a set of plugs handy, as it does something to plugs .I don't know why, but they tend to foul often after such a treatment.<br />I use ValveTect spray, but they all werk fine.<br />If your manual recommends an alcohol-free fuel, do not use the additive types, as they can devour rubber (valve seats, seals, fuel pump diaphrams ect).<br />But from what I understand (double check by all means as I'm bnot an OMC guy), OMC even recommends Seafoam additive! Go figure <br />There was a guy on a Florida-based boating/fishing site who used a shock-treatment meathod, by mixing additive to a small 1QT can of fuel, and running the engine until gone, letting it sit overnight, and then running fresh mix until the smoke clears...And it will smoke so heavily, don't be suprised if the nieghbors call the fire department.<br />By the way, you may allready be aware of this, but mention it in case you are not -- don't run it without thermostats for any length of time.<br />The heads and/or manifolds can warp, and the engine could actuially run so cool as to break a ring.<br />The way this point was driven home to me (on this site iuncidently, was "If the engine didn't require thermostats, the manufacturer would've left them out, and pocketed the 5 buks per motor that was saved".

 

[Jack Shellac]

Re: decarb method/products/additives

Ditto on the thermostats. Most of an outboard engine's wear occurs while the engine is warming up. If it's running cool all the time, it's wearing prematurely. Unless I'm mistaken, I believe your Johnson has a fitting to inject decarb. It's the tire-valve type fitting on the manual primer lever.

 

[roscoe]

Re: decarb method/products/additives

Decarbing is a 2 part process. One preventative, done by using a fuel additive to prevent carbon build up. SeaFoam is such a fuel additive and can be found at most auto parts stores. It works as a fuel system cleaner and should be used as a preventative maintenance procedure.<br /><br />If your intent is REMOVE the existing carbon buildup from the cylinders, heads, and rings, then a spray decarb solvent product is needed. Buy at least 2 cans of decarb. Some people use one can per cylinder.<br /><br />Run engine at fast idle, with engine running<br />spray liberal amount into each carb,<br />spray some more, spray a larger amount into carbs until engine chokes out and stops,<br />remove spark plugs and spray decarb liberally into each cylinder, install the spark plugs, let it soak for 1 to 12 hours. <br />Start the engine and run at medium throttle, or if at the lake, run it at full throttle. It won't hurt to spray some more through the carbs. Run it for atleast 10 minutes to flush the crud out of your engine. Now remove and clean or replace the spark plugs.

 

[sparkroost]

Re: decarb method/products/additives

SCO, how ya been! Did you get rid of that 1973 135?

 

[SCO]

Re: decarb method/products/additives

No Spartroost, just got an offer I couldn't refuse to buy 1/2 of a 95 Whaler Dauntless 17 that is hardly ever used. It is on a covered lift ready to go. I still have my garage space for the project boat!