75 HP mariner from 1991 - reputation and checks for second hand buy

[janneman]

last sunday my good ole ' 50 HP 2 stroke mariner grinded the gearcase into paste.... boohoo.

on ebay i found a 75HP 2-stroke autolube from 1991 (serial 09681211) and i wonder what the reputation of this engine is?

what tests could i perform locally to check its' health?

thanks!

p.s. have an impression of my boat; https://www.youtube.com/watch?v=g6EgApbVdnA

 

[tommarvin]

You could do a compression test.
Or a leak down test.
Get a used lower unit.
Get a used 4 stroke.

 

[janneman]

..
Or a leak down test.
...

what is that?

thanks for the hints

 

[flyingscott]

You do not need to do a leak down test. Is the 75 hp mariner a 3 cylinder motor? Can you get a mechanic to look at it? Is it close to you? Can you hear it run or test drive it? do the compression test. They are good motors with good power but like any other motor of that age depends how it was taken care of..

 

[janneman]

Is the 75 hp mariner a 3 cylinder motor? Can you get a mechanic to look at it? Is it close to you? Can you hear it run or test drive it? do the compression test. They are good motors with good power but like any other motor of that age depends how it was taken care of..

thanks Scott

it's a 3-cylinder yes - from the manual I learn it's 1150 cc. I've seen/heard it run over video-chat and the seller is a boat-mechanic.

At least from the outside it looks very well taken care of, still shiny even under the hood. What i also understand from the manual is that the 70 to 90 HP in that model all have the same displacement, just differt tuned carburators. What i like about that is that the 75 hp appearantly also is engineered to take much more beating and wear than it takes, in a way over-dimensioned.

I need to read about the compression test how i do it. what i learned once (the compression test for dummies);
unplug a spark-plug,
keep your thumb on the hole while the cylinder is up,
turn the engine so the cylinder sucks your thumb
the sucking should hold at least 10 seconds
(if not, it's leaking)

 

[flyingscott]

A thumb is not a compression tester. Get a gauge or have the guy selling it to you do it while you are there.

 

[janneman]

yay... it's hanging and looking pretty big for my 14" bathtub