1992 mercury 75hp over heated? - best route to rebuild myself / core exchange?

Joined
Jun 29, 2015
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Hey so sadly enough my motor the other day just died out of no where on the way home when i was cruising around 3/4 throttle for a few minutes 3-4 mins.

seems like the middle cylinder has some aluminum build up from the piston using a camera to look inside. I haven't checked anything yet but the only thing I can see being the cause is insufficient cooling? the tell tale was working but after doing some research it seems like even though its visually working it may not be providing adequate cooling.

I lost all my assortment of fittings for my compression tester so havent been able to check that just yet.

When it did start to die I shut it down right away, left it sit for a few seconds then tried turning it over and it didnt want to. Left it sit a little longer again and tried again still didn't turn over unti about 45 to a min of sitting i got it to turn over so alteast it didnt "lock up" thankfully but this type of problem usually tells me either it leaned out or over heated.

looking at the plugs the top and bottom plug are seemingly "normal" looking but the middle one being clean with no carbon or anything on it but didnt have any alum build up on it either.


whats your opinion from what I have mentioned on the potential cause?



What would be the best route to go to get this fixed. Is a core exchange worthwhile for about 2100 USD + reimbursement of the core you send in depending on condition which is pretty vague on how much you would exactly get back.

Or buying the rebuild kit and doing it myself which im looking at around 700 for the kit
 
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