2003 Optimax 200 OT674168
Just changed plugs and noticed bottom plug on each side of the block was carboned up pretty badly. Any idea what causes this? I only run Merc DFI oil and use Don’s cocktail religiously for every gallon of gas. Using NGK IZFR5G’s gapped at .033.
Check both thermostats for debris.
Savage, could you elaborate on why that would cause carbon build up?Originally Posted by Savage
Motor not coming up to temperature.....computer richens the mixture.....plugs get fouled.
Thanks! Keep the great information coming. I’m a newbie to this board. I’ve been following the Merc board and learning a ton.
Wayne
Engine Temp is critically important- also confirm you have 130 degree thermostats (and not 120's).
Amount of idling, or any fuel system abnormalities (or internal leaks) can also contribute.
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Thanks, Don. Installing new 130 degree tstats this weekend. Is it common for just the bottom two plugs to be dirty? The upper cylinder plugs looked pretty good.
Lower two will naturally appear darker, especially with a lot of idling.
If you did not have 130 degree thermostats already- there are some items that must be checked BEFORE retrofitting (specifically the covers).
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
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