Mercury 25HP 1992 ??<br />Serial# 0D085081 (this from welch plug and transom mount)<br />Model # 1025312MD ??<br />Friends motor, not mine.<br /><br /><br />Just a couple of issues, questions on motor above. This last weekend, replaced 13 year old impeller. Old impeller had 3 wiper arms going wrong way, one slightly cracked. Caught it just in time. Old impeller had taken a good set, like it had been setting for a long while (13 years looked about right). <br /><br />Question, Mercury manual shows 4 plastics isolators that pump housing bolts go thru (one for each mounting hole in both the pump housing and wear plate). Why-purpose the isolators?? Isolators were not present upon disassembly.<br /><br />I ordered a new thermostat for this motor too. When I removed the thermostat housing, yup, no thermostat. I installed it with new gasket. I noticed that the tell-tale comes off of this housing. I would guess (hope) that the tell tale is not going to be controlled by thermoatat opening/closing. It appeared that nothing was ever done to this motor. I noticed that the factory paint was still intact on all powerhead bolts etc and thermostat housing, no overspray (re-paint). <br />Question, did Mercury ship these motors without a thermostat (seems very unlikely). My manual shows powerhead with no thermostat.<br /><br /><br />The manual I have is original Mercury Service Manual <br /># 90-43509--1 683 18/20/25 HP<br />United States 6416713 and up<br />Belgium 9390291 and up<br />Canada 7207858 and up<br /><br />I'm starting to think I have an earlier manual and this would account for changes to this motor. If anyone can shed some light on the correct manual number, that might be the answer. <br />Other differences... This WMC carb has extra fuel pump body with integral metal check valves and round choke/primer knob that rotates to adj. idle speed.
