Liquid Mechanics May Be Your Answer
To Spring Motor Tune-ups
by Dan Armitage
The boat alone was worth the price of the entire package, so I broke Rule Number 1 and bought the boat, motor, and trailer without a test drive and towed the "find" home.
In the driveway, with the garden hose pumping water to the lower unit, I startled my quiet suburban neighborhood as the Evinrude roared to life--then died. Amid the sounds of barking dogs and glaring neighbors, I tried again and again to get the 115 to idle. I couldn't even get it to run at high speed for more than a few seconds before it died.
Finally, it was just too embarrassing to continue, and I succumbed to calling my mechanic--still pleased with my purchase but questioning the future of the outboard-end of the package.
John arrived the next evening straight from work at the shop, but instead of lugging over a toolbox full of hardware, he walked up from his truck carrying only a small aerosol can in his hand.
"Hop in there and get 'er cranked when I say so," he ordered, ignoring my questions about the absence of real tools. In the time it took me to hop over the center console's transom, he had the intake cover off and directed the can's nozzle into the carburetor, and said: "Let 'er rip."
As usual, the outboard jumped to life, and began to falter. But by that time John had shot several ounces of fluid into the engine. It coughed, but it didn't die as I kept the RPMs up over 2,000. The motor ran long enough to allow John to empty the can's entire 13 ounces into the engine, before it stalled when I tried to back it off.
As the breeze carried a cloud of dense white smoke into the neighbor's yard, I was about to re-start the engine when John told me to relax for awhile before giving it another try. Twenty minutes later, after running the engine for five minutes or so (which blew more smoke and left a smattering of black ooze on the garage door) the engine was idling nicely.
He submitted me a bill for $5.75 for parts plus a half-hour labor. The boat purchase suddenly seemed like a sweet deal again.
I was so amazed at how that single can of magic had "fixed" what I was sure was a major problem with the motor, I visited John at the boat dealership the next day to learn more.
"We go through this stuff like you wouldn't believe," said the certified OMC mechanic. "It's one of the first things we do when an engine comes in with complaints of poor idling. And more often than not, a can of this will do the trick," he added, tossing me a red, white, and blue can of OMC Engine Tune.
Since first repair revelation, I've done some digging into just what this stuff is, and how it works. Basically, the "tune-up-in-a-can" products offered by companies like OMC and Valvtect contain highly concentrated detergents, similar to what's found in high-test gasoline, but much more concentrated.
The detergents are carried in a solvent, aromatic hydrocarbons in the case of the OMC formula, and since the solvent is a petroleum distillate itself, both agents actually break down varnish, carbon, and other deposits in the combustion chamber. This cleaning action frees-up pistons and rings that have been gummed-up with the carbon deposits left behind by gasoline.
According to one industry spokesman, and backed up by my own mechanic and several others I've talked to, the problem of carbon build-up from today's fuels is much worse than it was a decade ago, and not getting any better.
"It's more important now than ever to use these cleaners regularly," said one high-performance marine technician for a major outboard manufacturer. "If you're using 87 octane, leaded or unleaded, no matter where you get it or what brand it is, you're layering on the deposits each time to run your outboard. It isn't much better with higher octane either.
"Look at all the additives their putting into fuel these days. It just doesn't burn as clean as gas used to. Carbon and other deposit build-up on marine engines wasn't a problem 10 years ago. Now it's major."
The technician explained that the deposits left by the cleaner gasolines of yesteryear were softer, and easier to clean or simply wear off. Now, he said, "it's almost like the stuff is glued to the pistons."
When that happens, the rings clog and don't allow heat to bypass, and the motor won't idle properly. If it gets bad, the rings can crack, scuffing the inside of the cylinder walls, letting pressure bypass them and reducing compression. Eventually, because the heat can't transfer from the piston to the cylinder walls, the piston expands and grinds to a halt in the cylinder. Things tend to shut down fast when that happens.
Dave Grochocki of ValvTect, which makes Marine Motor Tune-up, a popular aerosol engine tuner, explains that the tune-up-in-a-can products work much like oven cleaner. You apply the cleaner and heat the surface to be cleaned, allowing both the heat and the chemicals to the job. That's why both OMC and ValvTect recommend letting their cleaners sit inside a warm engine for 15 minutes to a half-hour before running the engine for the final clean-out.
Grochocki explained that not only are there more carbon and other deposits left over after running modern-day fuels, but the deposits are tougher to clean off due to two factors.
"First, outboards today are asked to work harder, perform better, yet be smaller and lighter that previous models. As a result, they run hotter," he explained. "Second, a gallon of modern fuel may contain up to 15 percent chemical additives to reduce emissions.
"Combine the extra heat with the extra chemicals and the carbon deposits left behind can practically bond to the cylinder wall. And because carbon attracts carbon, a snowball effect is created; once you get a layer on, it attracts more carbon faster than did the clean surface."
OMC and ValvTect both advise that boaters use a can of their product every 50 to 100 hours, or at least as part of annual spring maintenance. Grochocki recommends running a can through any engine before taking it to the shop for problems associated with loss of power or poor idling. My local marine mechanic agrees, saying that most shops will use a can of aerosol tuner as a first attempt to solve rough-running problems. Even if the cleansing doesn't solve the problem, the technician has a clean combustion chamber to inspect for other trouble, he said.
Both products are simple to use and may be used in both 2- and 4-cycle engines. With the engine running at operating temperature (make sure water is pumping through to cool the system), simply spray the tuner directly into the engine's carburetor throat. The engine should continue to run as you empty the entire can into the engine, during which time you may have to jockey the throttle a little to keep the outboard from stalling.
OMC recommends maintaining at least 1,200 RPMs during the spraying process. Once the entire can is empty, turn the engine off for 20 to 30 minutes to allow the chemical cleaners to do their work. Then start the engine as usual, and run at half throttle for three to five minutes.
OMC makes a special injection-style of its Engine Tuner, which comes with a clear tube and nozzle that attaches to a tire-valve-type fixture on late-model OMC outboards, located at the top of the fuel primer. Kits are available for adapting most OMCs to this system. ValvTect's Marine Motor Tune-Up comes in aerosol spray only, which can be used on all outboards, even OMCs equipped ones with the special tune-up injection valve.
The price of the two products is comparable. $5.75 is what I paid for the OMC injection style, and the Valvtect tuner has a suggested list price of $6.29. One can is used for each tune-up, although no damage can occur if you use more. There will be a lot of smoke, either white or white with a bluish cast, as the engine's running with the tune-up going into it's system, so make sure the area you choose to perform your "Liquid Mechanics" is well ventilated.
