APPRAISAL: 1971 Mercury 135 HP Outboard

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APPRAISAL: 1971 Mercury 135 HP Outboard

Postby dsheridan » Tue Sep 14, 2021 11:23 am

What is a reasonable selling price for a 1971 Mercury 135-HP engine, serial number 3116714, as seen below?

5E741AC5-0507-4762-8626-3B34F3F536FD.jpeg (34.94 KiB) Viewed 880 times

DBBCE543-5865-4452-BA69-2051F9FF1970.jpeg (53.98 KiB) Viewed 880 times

Included in the sale would be the original controls, ignition keys, tachometer, and two propellers. I believe the propellers are a 7-pitch (last used on a 28-foot pontoon) and a 14-pitch (originally on a wooden runabout).

Reply to this post with your opinion of the selling price for this engine.

LONG BACKSTORY: Hello everyone. I have a 135 HP six-cylinder Mercury that has been in our family since it was new. When I moved back to Michigan in 2000, I could not part with it. We brought it with us, intending to find a classic Whaler hull for a project. Well, here we are 21 years later. Outboard is still stored in the basement (heated, a/c). When we moved in 2000 we serviced it and winterized it. I have no doubt that it would start right up, if we serviced it again now. It was always a champ, and always serviced regularly. [The engine] is a bit dirty in the pictures.

Thank you,

Dan Sheridan
Saugatuck, Michigan

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Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula

Re: APPRAISAL: 1971 Mercury 135 HP Outboard

Postby jimh » Wed Sep 15, 2021 8:19 am

This engine would have two price ranges:
  • as a 40-year-old engine that has not run in 20-years to a general boater
  • as a intact classic Mercury six-cylinder in-line engine that could be restored by a collector or enthusiast that has a fascination with these engines
For the first customer, the engine value is not particularly high; unless you could demonstrate the engine running and propelling a boat, it would be difficult to sell.

For the second customer, the engine will have a much higher value, as it appears to be cosmetically in good condition, other than the neglected gear case paint.

Appraising the engine as a general boater, the first type customer, the engine value is almost zero.

I cannot appraise the engine as a collector or enthusiast, because I am not a collector of old outboard engines or an enthusiast for that particular engine, but I would expect that the value would be perhaps as much as $1,000. You should look into websites whose focus is in collecting and restoring this particular type engine--a Mercury six-cylinder in-line. You may find there is significant demand for this engine.

ASIDE: generally for someone to have a special attraction to an outboard engine from the 1970's, that person would likely have been involved in boating himself in the 1970's. This implies to me that in the 1970's the person would have been in an age range from say 15-years-old to perhaps 35-year-old. This means your customer in 2021 for the engine would then be in the age range of 65 to 85-years-old. For a younger person in 2021 to have a great interest in this engine seems unlikely. You should sell this engine before all those old guys interested in collecting and restoring them are gone.

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Re: APPRAISAL: 1971 Mercury 135 HP Outboard

Postby dsheridan » Thu Sep 16, 2021 11:43 am

Thank you, Jim, for the thoughtful reply. I will do some poking around on the web for enthusiast websites. If anyone reading this can suggest one, I appreciate it. If I find some good ones, I will post the details here for others to see.

Stay safe folks. Dan

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Joined: Sat Oct 17, 2015 7:44 am
Location: Merritt Island Florida

Re: APPRAISAL: 1971 Mercury 135 HP Outboard

Postby sraab928 » Fri Sep 17, 2021 6:20 am

If your looking around for enthusiasts you might find some on

Facebook has a few groups dedicated to the inline 6 motors as well (also referred to as the "tower of power) - Inline 6 mercury outboard fans - Mercury In-line 6 Outboard Enthusiasts
1971 Boston Whaler Outrage 21 - under restoration
1974 Boston Whaler Revenge 21

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Joined: Tue Sep 14, 2021 10:45 am

Re: APPRAISAL: 1971 Mercury 135 HP Outboard

Postby dsheridan » Fri Sep 17, 2021 10:04 am

Thank you, Scott!