Mercury 40HP, bogus serial number

[Boatleech]

I'm working on a 40HP Mercury that was apparently built up from scattered parts. It looks good, but the s/n on the transom mount appears to be 05084586, which, according to Mercury customer service, is from a '78 20HP motor. All I can tell from looking at it is it's a 2-stroke, 4-cyl motor, and says Mercury 40 on the cover. Can anyone give me some clues to determining what year and serial number range might apply based on visual inspection alone? I have no idea, of course, if the powerhead, lower unit, etc., are matched or not.

 

[Boatleech]

Re: Mercury 40HP, bogus serial number

The starter motor and switchbox both have 1994 dates on them, so I'm now assuming it's a 1994 or 1995 motor. Does anybody have a feel for how individual parts' dates relate to the "official" model year of the motor?

Dealer says there's also a s/n on the powerhead, but damned if I can find one. Is it hidden under the switchbox, maybe?

 

[Barnacle_Bill]

Re: Mercury 40HP, bogus serial number

Look on top of the motor for a round plug. You should find one with the serial no. on it.

 

[Laddies]

Re: Mercury 40HP, bogus serial number

The soft plug with the serial number should be above the port mounting stud for the bottom carb.

 

[Boatleech]

Re: Mercury 40HP, bogus serial number

Tucked in securely behind the oil tank, eh? Surprised I didn't notice it when I replaced the fuel pump, but I had other things on my mind at the time. Thanks -- I'll have another look.

 

[Boatleech]

Re: Mercury 40HP, bogus serial number

Look on top of the motor for a round plug. You should find one with the serial no. on it.

I've looked in all the easily-accessible places, but I guess now I'll start digging. If Laddies is right, I'll find it tomorrow, but if by the "top of motor" you mean underneath the flywheel, etc., I can wait .

 

[Boatleech]

Re: Mercury 40HP, bogus serial number

The soft plug with the serial number should be above the port mounting stud for the bottom carb.

Nope. Haven't found any such plugs (Welch plugs?) anywhere.

 

[Laddies]

Re: Mercury 40HP, bogus serial number

The blocks that were built in the 80s were also marked on both sides of the crankcase seam at the top on the port side I believe (it could be the starboard side) and the earliest place was on top of the block above the exhaust plates. There are also some unnumbered replacement blocks out there.

 

[Boatleech]

Re: Mercury 40HP, bogus serial number

Thanks; I doubt the block was replaced, but who knows? I have a background in aircraft maintenance, where -- most of the time -- the records of repairs and parts replaced are pretty detailed. This is a new world for me.

My "05084586" s/n on the flimsy plastic label on the transom mount (of all places) is really "0?084586", but what's left of the "?" looks an awful lot like it once was a 5. So far, though, my guess that it's a 1994 or 1995 seems to be working out.

 

[Laddies]

Re: Mercury 40HP, bogus serial number

The starting number for 1992 was 0D082000 and in 93 was 0D182000 for 40 HP 4 cyl engines

 

[Boatleech]

Re: Mercury 40HP, bogus serial number

Yeah, I'm struggling to try to make that second character a D or a G. I see the 1994's were s/n 0D279350 - 0G116484, and if that series included a "0G084586" that would be more believable than "0D984586". That would also be consistent with the dates on the switchbox and starter (but they could be replacements, obviously). I'm going out of town for a week or so, but I'll try to get a good closeup picture of the s/n tag when I get back and let you have a guess as well.

Thanks...

Mike