kmatus wrote:
We bought our first small boat for lake fishing a week ago. It is a
used 14' jon boat circa 1981 (according to the license). It had on it

a 40 HP MERCURY engine with serial number 5991890. (With electric
start).

OK - here is the part where you can call us stupid. My first guess
(we didn't ask but should of - excitement of buying a boat that we
could use with out boys - ages 12 and 7 - you know) was that it was a 2

cycle. My wife insisted she saw on the sign that it was a 4-cycle. Of

course, had I bothered to look for a oil reservoir, I guess I would
have had my answer. However, not wanting to doubt my wife (long story

there) I took it on faith that it was a 4 cycle and we put premium gas
into the fuel tank with no oil added.




I wasn't aware Mercury ever made a 4 cycle, and if they did it's
*highly* unlikely a motor of that size and age is. It's easy enough to
tell though, a 4 cycle motor will have an oil filled crankcase with a
dipstick or other method of checking the oil as well as they will
normally say 4 Stroke somewhat prominently on the cowl.

My guess is that the motor is toast, you ran it without oil, the rings
probably galled the cylinder walls and the bearings are likely shot as
well. Only way to tell for sure is to do a compression check. It *may*
be possible to have it rebuilt if the damage is not too severe but I
think most will tell you to shop for a new motor.

Chalk it up as a lesson learned, *always* verify for absolute certain
what the fuel requirements are before running a motor. Oil injection is
a fairly recent development, until the 90s most required oil to be
premixed with the fuel in the tank.