Extreme Smoking

[Pete Caballero]

I have twin 150hp 1991 Mercury on my boat. Both engines run fine but recently my starboard side engine started to run slightly different (a little rougher). The same engine now smokes an extreme amount when I first fire it up. For about 5 minutes in burns an incredible amount of oil much much more that the other engine. It did not do this in the past. Once the engine runs for about five or 10 minutes I can shut it down and start it back up with little to no smoke. It only does this when it is cold. The spark plugs are about 18 months old but don't really have a lot of run time. Any ideas as to what is going on?<br /><br />------------------<br />Thanks, <br />Pete<br /><;}}><

 

[Deeznutz]

Re: Extreme Smoking

Maybe you should try and run the motors a little more often and change your plugs more often! <br /><br />I would check the oil injectors, they could be stuck open on that particular cylinder.<br /><br />I believe they are sort of one way check valves. If they are stuck open then maybe oil is dripping in the cylinder while the engine is off. SO when you first start it, it smokes like a mofo and fouls your plugs. Which is why it might run rough!<br /><br />I dont know if this applies to mercs though.<br />But it's worth checking out!<br /><br />Later,<br />Rosa MelTronco

 

[Pete Caballero]

Re: Extreme Smoking

Thanks, that makes sense. Have you ever heard of fuel boiling out and leaving the oil in the cylinder? Someone told me that was also a possibility, but I don't understand why it would happen to one engine and not the other. Supposedly this is common in hot wheather. <br /><br />------------------<br />Thanks, <br />Pete<br /><;}}><

 

[clanton]

Re: Extreme Smoking

Look at the pumps, they have a return spring, linkage to carbuators, and marks to adjust the pump. Both engines the same? There is check valve between the oil pump and fuel pump, if this check valve was leaking, oil might flow into the fuel lines as fuel drained from line to tank, when engine sat. Then when engine is started fuel line is loaded with oil. From the drawing Im looking at the oil tank is air tight which would push more oil into the line in hot weather.

 

[Pete Caballero]

Re: Extreme Smoking

Thanks, I'll definitely check those parts. What book are you referencing and is that a good book for a backyard hands on kind of guy?<br /><br /><br /><br />------------------<br />Thanks, <br />Pete<br /><;}}><

 

[clanton]

Re: Extreme Smoking

OEM service manual for Merc 1999. I like it lots of pictures.