Before posting this, I searched not only this site (a wealth of applicable information), but also the web in general (for any and all ideas about decarbing).<br /><br />Just trying to get a sense, when to know if the job is considered "done" to the best of it's ability, short of mechanical removal.<br /><br />As a background, last year, elated to finally get my '64 40HP Evinrude running thanks to you folks, I decarbed my engine using SeaFoam. I opted to use the technique of squirting some into the carb (via a squirt can oiler) while the engine was warmed up and idleing, until bogging it down. I let it sit 15 minutes or longer, started it up, held my breath, and observed the "debris" on top of my water tank.<br /><br />At that time, I was at least elated to see a black slick of goop in suspension on top of the water, and per previous posts, this seemed like an adequate visual identifier, to suggest the black carbon had been blown through the exhaust.<br /><br />So, I was happy then...but fast forward to this year (keeping in mind that last year, I probably logged less than 15 hours total, over the course of 6 outings w/ this motor). To boot, the standard procedure is to fire it up and go WOT, I basically don't troll, just tow or cruise the pond, but never at low RPM (which I was under the impression, would be likely to be the more favorable conditions to accelerate carbon buildup).<br /><br />So, now that things are in good working order, I decided again for the sake of it (more time on my hands than anything else at this point) to do another decarb.<br /><br />I again used the same SeaFoam method, warmed up and squited through carbs till bogdown, and let sit for several hours. Upon start up, and post smoke, I again saw the black matter in suspension on top of the water (is it really possible that it got that carboned up again after just a few short uses)?<br /><br />Or, perhaps more significantly, maybe that treatment a year ago, really didn't get it all, and there was still plenty remaining.<br /><br />To "TRY" and be sure, I then decided to run an additional can of Sea Foam, mixed in w/ one properly mixed oil/gas in a gallon, and did the 15 minutes run to 15 minutes rest method, to see what came of it.<br /><br />Well, smoking was markedly reduced the whole while, and after all was said and done, there was no black oil/carbon debris on top. So, job done, or not?<br /><br />Since performing the procedure, I and seeking parallel functions to do the job, I opted to try them as well.<br /><br />The spritzing water down the carb in small quantities to "shock" the carbon and speed it's removal, harkens back to the days of WWII when they used it in planes to clean them up, due to fuel shortages and mixing together of whatever inferior combustibles were at hand to knock off the accelerated formation of carbon.<br /><br />Seems like a pretty sound idea (though I know opinions vary)...but even so, I tried a bit w/ a spritz bottle...maybe I never even got enough in place to do anything, but figured better to err on the side of less, than risk a hydra lock w/ too much at once (for what it's worth, seems like on high performance cars, a bit of water injection to decarb is not all that uncommon a remedy, so it must have it's place somewhere)...in any case, after such experimentation, there was no black aftermath...so, hard to tell if it did anything...the motor ran about the same (no pistons melting), but what about the 3rd alternative.<br /><br />The ATF (Automatic Transmission Fluid) treatment...basically, use it the same as Sea Foam (or more or less, any of the major boat manufacturers decarb products)...spray through carb, wait for smoke and bogging, then let it sit a while and restart.<br /><br />That brings me to where I am now (not being a favorite, no doubt, amongst my neighbors)...but, after running while spritzing the ATF through the carbs, it's clear that there is still a "goop" of sort running out and settling on the water's surface...at this point, it's more of a dark brown material...you can also clearly see it running from the exhaust port on this motor...so, something seems to be loosening, that's different from before, since in no other combination of techniques did I have matter leaking from the exhaust.<br /><br />After I let it sit overnight, and fire it up tomorrow, I'm intent on one final last treatment of squirting SeaFoam in till it bogs, and let that sit in there for the remainder of the week...what else can I try at this point!?!<br /><br />I'm happy that so far I have at least not caused any discernable harm...as I suspect, in the life of this motor, I'm probably the first person in the last 40 years to take a stab at trying to decarb it.<br /><br />It'd just be nice to know when to stop, to know you've done the best you can (as that point to my 3 pronged approach of water, ATF, and SeaFoam)...granted, given the cost of a new outboard motor these days, you'd be a fool not to keep up w/ some sort of regular maintenance and the applicable products and tried and true methods to boot.<br /><br />But, just looking for opinions and suggestions, as it seems like 1...or for that matter 4, treatments and plans of attack still seem to be yielding some gook.<br /><br />I figure, the cost of these products is negligable, time is a plenty, so why not keep mixing up a variety of approaches till I can run it, look in the bucket, and say "that sure looks better than it did before".<br /><br />Since it's run at WOT 95% of the time anyway, so far as I could tell, it ran satisfactorily before the decarb attempts anyway...but afterwards, you notice the low RPM improvement (just rather not crack a ring).<br /><br />Thanks for any input.
