Mercury Mark 58AE

About inboard or outboard motors.

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Mercury Mark 58AE

Post by lts70 »

I am working on getting started on restoring a couple of my grandfathers old fiberglass boats. A 1957 Glasspar Sport Lido boat and 1958 Dorsett El Dorado.

The main reason I am so drawn to this project is the look of the mercury mark 58ae 50hp (serial # 12231123). Only problem is that it has been sitting out in the sun for the last 25 years. I really want to get this motor back into reliable condition as a starter to this project. I have been surfing the web looking for information on the possibility of a successful restore of this motor.

So I am hoping I can get some advise on how to start the resurrection of this motor. I have pulled the plugs and poured seafoam in the cylinders. it does turn over. If you have any advise on things to do please let me know it would be greatly appreciated.

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Joined: Sun Oct 05, 2008 8:03 am
Location: Seattle, WA

Re: Mercury Mark 58AE

Post by BillW »

You should go to and ask this question.
There are lots of very knowledgeable folks there who will be glad to offer advise.
There is at least one who will do a professional re-build.
I think that sitting outside for 25 years makes it a likely candidate for re-build.
The Mk58 is a great motor. I have a 58A.


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Joined: Tue May 05, 2009 12:18 pm
Location: Raleigh, North Carolina

Re: Mercury Mark 58AE

Post by gdcarpenter »

Hi and Welcome,

Among vintage outboard folks thosethat work on Old Mercs are often referred to as 'Going to the Dark Side'.

I have only worked on old 4 cylinder Mecs so cannot speak to the other brands. They are different, and there is quite a learning curve. My first was a 1959 Mark35A and I restored everything but the power head, as the engine was given to me by my uncle who owned and cared for it for years and years. The second was a 1958 Mark58A on which I rebuilt the engine as well. They are solid engines and well repaired and tended to their sound running away at 5,600 RPM is music to the ears.

Though more challenging, I would recommend not trying to start it, but to tear it down. After 25 years of sitting some of the multitude of individual roller bearings on both ends of the con rod could be pitted and firing it up could make an otherwise restorable engine worse off. The water pump impeller is likely disintegrated into tiny pieces of hardened rubble that could run through and plug up the water passages.

The folks at John's Old Mercury site are very helpful indeed, even to novices. There are parts available once you get into the 'Dark Side' network of 'Mercaholics'.

All the best.
This is my first, last and only boat build.

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