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Merc 18hp 2 or 4 stroke engine

K

Kevin Birch

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" Just bought Merc 18 XD seria

" Just bought Merc 18 XD serial 91414939 (mid 1980's), I was told it is a 4 stroke engine not 2 stroke. Can any body confirm this as I don't want to start it withuot any oil in the fuel with disasterous results if it is a 2 stroke.If it is a 4 stroke engine how does the crankcase get its lubrication and how do I change it(doesn't seem to be any drain plug etc.) If it is a 2 stroke I presume 50:1 mix is ok. I know these may be simple questions but I want to get it right, I'm familiar with stripping car engines( v8s and even Lotus twin cams)but am very new to boating and outboards seem to be complicated and expensive!!!

Any info appreciated,

Regards Kev. "
 
" 2-stroke. Mercury didn'

" 2-stroke. Mercury didn' come out with 4 stroke motors till the late 90's. Tried to match your serial to Mercurymarine.com, but was listed as incorrect. Mix is 50:1 "
 
" Kevin,

The model and seri


" Kevin,

The model and serial number indicate a 2 stroke engine. A four stroke engine would have to have a camshaft turned by a belt or a gear, and an oil pump, valves, etc. That is a lot of stuff and it is obvious. Four stroke engines have a different fuel supply system, unlike the carb and intake reeds on your two stroke. And of course the fuel mix runs through the crankcase, which is also obvious due to the placement of the carb.

You should use 50-1 fuel/oil ratio.

Tony "
 
" Tony & Tom

Thanks for


" Tony & Tom

Thanks for your help you've confirmed my suspicions, will get some oil and start it up this week.

Regards Kev "
 
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