Mercury serial numbers??

[amuller]

I’m not too familiar with Mercury and am baffled. I have a motor with this serial number: 4981805. It’s an inline 3.

It seems this *might* be a 1978 70 hp, but searching on that serial number turns up nothing.

The site https://public-mercurymarine.sysonline.com offers several "archive catalogs" including "serial number groups" that seem overlapping.

I’m sure there must be some obvious ways through this maze. Can anybody guide me?

Thanks!

[mercuryspecialist]

Our factory serial number charts do agree that 4981805 would be a 1978 Merc 700 (70 horsepower) assuming that it is an in-line 3 cylinder. There was only the 700 model offered in a 3 cylinder (for 1978), 4825249 is the starting serial number for these for 1978, and 5128280 is the starting serial number for 1979 and referred to as a Merc 70.

Regards,
Joe

[amuller]

quote MercurySpecialist:

Our factory serial number charts do agree that 4981805 would be a 1978 Merc 700 (70 horsepower) assuming that it is an in-line 3 cylinder. There was only the 700 model offered in a 3 cylinder (for 1978), 4825249 is the starting serial number for these for 1978, and 5128280 is the starting serial number for 1979 and referred to as a Merc 70.

Regards,
Joe

Thank you very much.

The story I’m given on this motor is that the prop, shaft, entire gearcase contents were ejected from the housing during operation. Is this something known to happen?
2nd question: Are there service manuals online for these motors?

Alan

[mercuryspecialist]

Hi Alan,
Our business never experienced such (Mercury dealership for 50+ years), nor do I remember hearing of it.
I unfortunately would be one of the last to know about online manuals for this or other brands/models. If I should not see additional questions before too much passage of time, do feel free to write to me at info@fergusonpoolemarine.com

Regards,
Joe

[billw]

I never heard of complete ejection, either. By 1976, Mercury finally got stainless prop shafts, shift shafts and drive shafts. This took Mercury from a company that had the worst gear cases in the business, to a company that maybe had the BEST gear cases in the business. That same basic case was used on 35 through 70 hp models and was very reliable. Although it might seem like the 70 was pushing the higher limits of a 35 hp case, the 70 was really kind of anemic for it’s advertised horse power. The OMC 70s would smoke them, as did the later-to-come Yamaha 70s. But I digress. I think the only way yours could have ejected the gut would be that someone mis-assembled it or it hit an underwater obstruction and the case cracked open, allowing the cover nut to come free of its threads…..

Long live American manufacturing!

[kerry]

Boatinfo has a generic service manual that may help. http://www.boatinfo.no/lib/mercury/manu … 15.html#/0

If you have too many, AND not enough, you're a collector.

[seakaye12]

quote amuller:

2nd question: Are there service manuals online for these motors?

Alan

[/quote]

These folks have PDF Mercury Manuals. Not free but $5.00 is pretty close to free. I have bought a couple from them.

http://mercury-2-stroke.marineservicemanuals.com/

Chuck

[amuller]

Thanks for all the info. I didn’t know Boatinfo was back on line. There is a manual there that’s helpful, but incomplete (like most aftermarket manuals).

This motor is rated at 70 hp but is only 50 cu inches, so I wouldn’t expect huge, gearbox-destroying torque.

Spitting out the innards of the gearcase seems odd to me. The PO seemed candid in other respects…

I mainly wanted this motor for the tilt-trim hydraulics.

[amuller]

So this motor is a conventional crossflow design, or is it the Mercury "direct charge" design?

[kerry]

Direct Charge. I may be wrong, but I believe its half of an inline six.

If you have too many, AND not enough, you're a collector.

[Author]

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