Merc Powerhead Identification

[jslu]

I have a 40 HP Merc powerhead that has been transplanted onto a 1987 35 Hp bottom assy as identified by the sticker on the transom bracket. Mechanically, it is an exact replacement.

By looking at the 40 HP powerhead components, triangular fuel pump with water cooling lines passing through and exiting to pee hole, different throttle and shift assy, thermostat and poppet valve installed, no overtemp warning (no provision for overtemp sensor in the block), and some other differences from a 1987 engine which I have intact and running.

This 40 HP powerhead does not have the typical "nickel size shiny freeze plug" installed in the block with the serial stamped into it on the upper starboard side of the block as later models do, it is only a black painted plug.

I have been able to ascertain that power head is prior to 1983 since that is when considerable minor modifications were made to revise HP rating (crank vs prop rating) and other changes to ease maintainance and resort to no a thermostat or poppet valve required and overtemp warning provided (more reliable??).

My question is ::: Are ther any other identifiers on this powerhead that would indicate it's actual year of manufacture ???

Thanks,

John

 

[Chinewalker]

Re: Merc Powerhead Identification

If there is no silver plug, serial may be stamped into the block, 7-digits, usually on top of the block, behind the flywheel.