Mercury Repair Questions? Ask a Mechanic for Answers ASAP
Do you know what codes are stored?
Have you tried a new thermostat and coolant flush?
Do the cooling fans work?
Have you checked for any debris on the exhaust system possibly to blame for this smoke?
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I am going to need to know what the smoke is from. It has to smell like something. It almost has to be coolant or oil to blame.
You need to look under the intake and try to see if there are fluids visible from a leaking valve cover or intake gasket.
I doubt it is plastic since that would eventually stop or actually flame up, it would have to be on the exhaust to melt and burn plastic.