Exhaust is Killing Me (Literally? Hope Not!)

[l008com]

As you can see from my pic, I've got a 15' thundercraft with a 90hp 2cycle 3cyl Mercury. Engine is an '89. So it runs great. Like, really great. It really runs like new. But the exhaust is brutal. I guess that's the price you pay for a 2 cycle. Even if you're going into the wind, the exhaust smell is strong. If you're going with the wind, you're clothes are going to need to go straight into the laundry when you get home. This isn't colored smoke or anything like that. Just the regular strong exhaust this engine has always had. So the question is, is there anything that can be done to reduce the gag factor?

 

[CharlieB]

Re: Exhaust is Killing Me (Literally? Hope Not!)

The low pressure area formed behind the prop while underway helps pull exhaust flow thru the prop and disperses most all odors as the bubbles rise thru the water.

If there is a restriction in the lower unit exhaust passage or the lower part of the mid-section then exhaust pressure rises, forcing more exhaust out the upper idle vent ports just above the water line in the mid-section.

I suggest you remove the lower unit and inspect all exhaust passages for foreign accumulation, such as mouse nesting, mud dobbers, or possibly even large carbon deposits.

 

[Chris1956]

Re: Exhaust is Killing Me (Literally? Hope Not!)

You might try a semi-synthetic or synthetic 2 cycle oil. Sometimes these smell less and smoke less.

 

[8hygro]

Re: Exhaust is Killing Me (Literally? Hope Not!)

Current fuel quality also plays a role in this. The lack of light ends and the high end point of production pump fuels can make clean combustion very difficult. Strong spark is critical.

8hygro

 

[Dave1027]

Re: Exhaust is Killing Me (Literally? Hope Not!)

I reduced my fumes by fine tuning the oil blend ratio and adjusting the timing.

 

[jeffersondodson561]

Re: Exhaust is Killing Me (Literally? Hope Not!)

Are we talking about exhuast or gas fumes?

 

[pine island fred]

Re: Exhaust is Killing Me (Literally? Hope Not!)

Quite possible the float levels in the carbs are to high, to rich a mixture but not enough to produce black smoke. 2 strokes are intentionally run rich to prevent possible detonation. BTW, although both terms are use, detonation and pre ignition are two different things. Did you ever notice how a 2 stroke runs better just before it runs out of gas? FRED

 

[l008com]

Re: Exhaust is Killing Me (Literally? Hope Not!)

Hmmm the forum didn't tell me about any reply's... About exhaust out the prop... problem is most of the places I boat are no wake zones. So I'm usually going slow enough that that doesn't happen. The plugs are pretty new so I think I'm good there. How do you adjust the float level in the carbs? I suppose I can try a new oil next year. I've always just put good old quicksilver oil in there because, thats what we've always put in there.

 

[l008com]

Re: Exhaust is Killing Me (Literally? Hope Not!)

Yeah so I'm just now running out of oil from when I started this thread. SO my question is... if I switch to synthetic oil, is it ok to mix them? I don't have to do anything crazy like drain the old oil, do i?The tank is just about empty, so it won't be much of a mixture.

 

[j_martin]

Re: Exhaust is Killing Me (Literally? Hope Not!)

Any TCW3 oil is miscible with any other. When you get into the super bean oil stuff it maybe won't. If you can get PennZoil full synthetic, give it a try.

Most engines that have oil injection have a linkage that changes the mix with throttle position. Look it up in your factory service manual and make sure it's right. With real good oil you can alter the setting slightly leaner and be OK. If you don't have a factory service manual, get one.

hope it helps
John

 

[CharlieB]

Re: Exhaust is Killing Me (Literally? Hope Not!)

When was the last timie the carbs where cleaned and adjusted, if the exhaust is strong from an ioverly rich mixture the floats may be too high of one carb flooding.