smoke inside cover while running..'89, 125hp force

[dmas]

hi

hope anybody can answer this question..my '89 125hp force was running great..but las time I run the engine on the water I've noticed smoke coming out of the vent hole on top of the cover while the engine was running..it smell like exhaust smoke, after I got home and run the engine with the hose I also notice smoke comming out of engine leg cover also..it's like the exhaust smoke is going inside the engine thru the engine leg cover..I took the lower unit out and didn't see anything wrong whit it..any ideas?.. thanks

 

[force fan]

Re: smoke inside cover while running..'89, 125hp force

There is a rubber tubular bellows that carries exhaust gas between the exhaust manifold to the mid leg housing and then out. The bellows may have a hole in it. It is only press fit between the two metal surfaces and I have noticed that it doesn't always carry 100% of the gas out, especially at idle speed. Run the engine without the cover and check for leaks. Check again with the boat in the water (or engine in a tank) so that water will create back pressure making the leak possibly more pronounced.

I bought my boat (new) in Colorado Springs, hauled it all the way to Austin, TX, and the first time I took it out I noticed the same thing happening (only worse). Turns out the entire bellows part was missing and the engine was choking on its own exhaust since the exhaust wasn't being directed outwards.

1988 Blue Fin 1700
85 hp Force

 

[dmas]

Re: smoke inside cover while running..'89, 125hp force

thanks force fan..I'll check that tomorrow

 

[Frank Acampora]

Re: smoke inside cover while running..'89, 125hp force

You will see the black rubber bellows about 5 inches below the head. It is spring loaded in order to keep the beveled end inserted into the taper on the rear shroud. Sometimes the bevel is not seated properly in the taper so you need to reach down and wiggle it in. You should be able to feel the pressure of the internal spring. If for some reason the previous owner had replaced the bellows and did not replace the spring, the bellows will not seat properly. The bellows is held to the engine leg boss by a spring type hose clamp. While I have never seen this, it is possible that the clamp has rusted off and gas is leaking out the engine leg side.

If that doesn't work, there is a plastic insert in the beveled end of the bellows. Sometimes, for various reasons, this plastic insert melts and distorts, keeping the bellows from sealing in the tapered seat in the rear shroud, If that's the case, you need to buy a new one.

Consider yourself lucky. Very often, when the bellows is not seated, the engine will stall at idle with the cover on. Take the cover off and it runs fine. Confuses the hell out of those who don't know.

 

[dmas]

Re: smoke inside cover while running..'89, 125hp force

thanks Frank, I checked those 2 things that you talked about but they were all fine, weird thing is that I put the lower unit back on, added some gasket maker compound around the lower unit, where it seals with the leg, turn it on and no leaks so far, now I have to check with the boat running on the water, I'll let you know how it goes. thanks again.

Dan