Merc Outboard 9.8 milky discharge from prop

[racerone]

JimS------Are you sure that is what is meant by " loop charged " ???---Because why would you recycle combustion products through an engine ?

 

[opalized1]

you recycle to make them a cleaner engine, less unburnt fuel and oil discharging into environment. Would be my guess,
I don't know, I do know my 1967 950ss, absolutely pucked horrendous amounts of black tar after shut off for the first month I ran it, then it seemed to clean out considerably over the next month to the point there was hardly any discharge after shut off, but this motor had sat and who knows how the prior owners had treated it. and I trolled 12 hours a day with the motor from the first day I ran it, which didn't help, it would run near wot to the fishing hole then troll all day and then wot back to ramp in afternoon, I did run marvel mystery oil through the motor in the fuel for the first couple tanks, so im sure this helped break loose all the old crap inside, and I would guess made it run better with each tank full. I am a true believer of the power of marvel mystery oil, it is one of the best additives I have ever used, in all applications from lawn mower to big v-8 engines, for use in gas and oil.

 

[racerone]

Sorry, the term " loop charging " has nothing to do with " recycling " exhaust material on a 2 stroke motor !!

 

[opalized1]

The cylinder has two types of ports: intake and exhaust. The piston travels down, opening the exhaust ports first to expel burned gasses. On the downward movement the piston uncovers the intake ports and displaces the fuel-air mixture in the crankcase into the cylinder. How the incoming mixture is distributed determines if it is a cross-flow or loop-charging system.

A cross-flow fuel system flows in one side of the cylinder and exhausts out the opposite. Loop-charge engines bring fuel in from other ports around the cylinder. This provides a circular motion. Loop charged engines handle the fuel and remove the exhaust more efficiently. This provides better fuel economy and performance. Cross flows may have better running characteristics at idle. Loop-charge technology designs are replacing almost all cross-flow designs.

 

[racerone]

And " loop charging " is nothing new.----Was used on Lawnboy / Iron Horse engines in the 1950's.----Those were a product of the Johnson / Evinrude factory aka OMC

 

[opalized1]

Agreed it doesn't specifically reference recycling exhaust in any manner related to the above term, loop charging, which originated originally in early 1900s on motorcycle engines and diesel engines and such, was around long before OMC began using it in outboards

In 1925 Gasmotorenfabrik Deutz in Germany introduced a two-stroke Diesel with a newly patented cylinder port design, the three-channel reverse flushing combustion chamber for 2-stroke diesel engines. Instead of a deflector on top of a piston, the looper design used a flat piston and 2 intake ports facing away from the exhaust port. The intake fuel charge was aimed to the opposite side of the cylinder and slightly upwards, thus causing a looping action which expelled the exhaust gases from the combustion chamber more efficiently than in previous designs. The research for this engine was performed by engineer Adolf Schnurle (1897- 1951). Schnurle's focus was on the development of big stationary engines, not small motors.

 

[JimS123]

Pardon my analysis. I misspoke when I referenced Loop Charging. I had the right idea in my head, just said it wrong.

First of all, a 2-stroke has oil in the gas. Whatever isn’t burned goes out the exhaust and drips. Along the way it mixes with some of the cooling water, thus the source of your milky discharge.

Loop-charging causes superior efficiency and power/performance. The path of the incoming fuel charge during the loop scavenging process leads to less fuel escaping through the open exhaust ports. The fuel that stays in the cylinder is more thoroughly utilized, so less is needed in the first place. These two things lead to less spilling of unburned gas/oil from the exhaust than with the cross-flow design. In effect, semantics or not, that is what I would consider recycling of a sort.

In addition to lower fuel usage and better combustion, the fact that oil ratios have come down from 16:1 to as low as 100:1, in some cases, has itself reduced the amount of oil discharge.

My 1953 25 HP Big Twin with a 24:1 ratio is run mid to full throttle all the time and it drips for weeks after I put it back in the garage. OTOH, my 1984 9.9 with a 50:1 ratio runs at dead idle trolling for 5-6 hours at a time and it never drips a drop (and it isn't even loop charged).

 

[Sea Rider]

My current loop charged OB still makes oilly water when flushed on a barrel at idle, fast idle speed. How much depends on how long you flush it and we're talking about 50/60 : 1 fuel/oil ratios. As hate cleaning oily barrel afterwords, for me muffs all the way..

Happy Boating