1985 90hp Mariner Inline Six Back To Life Question

ejthomp

Seaman Apprentice
Joined
Jan 12, 2009
Messages
32
Question first.... What else should I do or look for on a motor that hasn't been run in years? I'm worried about the internals of the motor having corrosion and the thing failing soon after I get it running good. Is there a way to inspect the internals without tearing it apart? First thing I did was a compression test....solid 145psi on all six.... looks good there. Incredible really. Does a good compression test tell me all I need to know in regards to the internal well being of the motor?

A friend has given me this obviously low hour motor because it has just been sitting (outside) for many years and the boat it is on is completely rotten due to exposure. My plan is to see if the motor is worth saving and then if so, put it on a different boat.

Anyway, I hooked up a battery to the motor along with some fresh gas and amazingly it fired right up. Although it is not running smoothly and missing on cylinders 1, 3, & 5.

As a precaution, I changed the water pump so I have good water flow and I changed the lower unit fluid which was old, but relatively clean. It shifts good....lower unit is good to go...

Checking the voltage at the rectifier revealed no charging voltage coming from it (12.6v...same as battery) and the wires from the stator are very bad. The insulation on the yellow stator wires is cracked and falling off. So immediately, I see I am due for a new stator and rectifier so that is $200. Whether that is responsible for the miss on 1,3, & 5...time will tell...maybe I will need a powerpack too.

Then I see that the carbs are all leaking. Squeezing the fuel line bulb causes them to just pour fuel. rebuild kits are only $20 a piece...so $60 there.

So...on the low side, I'm $300 into this motor before I sneeze. Not to mention my labor (but I enjoy this stuff so no biggie). Odds are that I will be $500 of parts in this motor to get it running smoothly.

Externally, the motor looks great. Paint and decals are all fresh. It really looks nice. It has very little wear. Just a shame it has been sitting outside for years.

Any advice?
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,416
Re: 1985 90hp Mariner Inline Six Back To Life Question

Sure, Clean the carbs and see if the missing clears up. Use new gaskets, floats and inlet needles and seats. Cylinders 1,3,5 are powered by 1 switchbox, so check it for corroded connections.
 
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