Bad news boat

[gstock]

I've got a mercruiser 170 4cyl 1986 model. We've had problems for about 3 years with this thing. We just got the ignition system replaced, and also we got the head gasket checked out, we know there is enough compression. They say it is all ok. But every time we go out fishing with this and we idle for around 5 hours or more the thing start to puff out nasty smelling almost yellow smoke, then it stalls and we see a mix of what looks like oil for sure and gas maybe coming out of the lower unit exhaust. Then when we try to start is back up the mixture comes out and it seems to be flooded. Then we have to sit there and wait, because it wont start. It'll run great if we dont idle. Does anyone have any suggestions before we throw more money into it?

 

[JasonJ]

Re: Bad news boat

Get a kicker motor. Those Mercuiser engines are marinized automotive engines, and they are set up to run continuously from mid rpms to redline. Idling any engine under load is hard on it, especially for five hours. The engine, unless it has a thermostat to regulate temperature, doesn't stay hot enough for proper combustion. Yeah, people do it all the time, but they don't understand that they are ruining their engines with improper use. You may need to change the heat range of your spark plugs to compensate for the overly cool combustion chambers, but then you run the risk of problems at cruising to top speeds. Again, if it runs fine any time except after continued idling under load, I would let a kicker do the trolling.<br /><br />BTW, I lived in Madison in the late 70s as a kid, near an arburatum not too far from fish hatchery road. I remember that place had the most horrid winters, tons of snow, ice storms, and in the summer plenty of bad thunderstorms and tornado warnings. I still liked it there though....

 

[Mod2]

Re: Bad news boat

Moving to I/O forum.