1988 Mercury 45 Classic 50 rebuild

MercNub

Cadet
Joined
Jun 21, 2009
Messages
16
Hi everyone. I have a 1987 mercury 45 classic 50 outboard. I have made some posts before on the forum and appreciate the help everyone has given me.

Latest engine disaster:blue: The last two times I went out I noticed a heavy green gray milky sludge coming out of the exhaust on the prop. I took the sparkplugs out and they where very clean almost like brand new. I also could not get the engine started or keep it running when it kicked over. I bought this engine 25 years ago and did have one overheat do to a bad impellor which caused scouring on piston number three which you could see from the intake port side. Based on these two problems I decided it was time to take the powerhead off and open it up to see what was going on.

After I opened the powerhead up I found the two problems which I had suspected. The lower crakshaft o ring seal was broken and was missing about 1/8th piece which I assumed is where the water was coming in and causing the white exhaust sludge. I also found that the piston three scouring had pinched the rings on the exhaust side so they could not expand which is why that cylinder only had 105 compression instead of the other three which have 130 psi.

The question I have now is do I just replace the upper and lower crankshaft seals and the scoured piston and all the rings or should I buy a full rebuild kit with pistons, needle bearings etc. I have checked the cylinders with an inside bore gauge and they are only .0005 to .0010 off so I think the block is still good with out boring it out. All the pistons except for the bad one look very clean with no scratches just some carbon on the top. I guess the seafoam really does clean the carbon out of the engine?

Also should I risk taking off the exhaust port to replace the gaskets and risk a broken bolt? So far I have been lucky and not had any broken bolts.

Also I can not get either the lower or upper ball bearing pieces out by hand. The Mercury manual specifies a special tool, but I can not find one to buy anywhere. Is there another tool to use to pull these ball bearings out? I think this is only a concern for the lower bearing as the seals are below it and you have to put them in from the top, the upper one is visible and can be removed and replace without removing the bearing.

Also I am a ok mechanic for small things tune ups spark plugs oil change etc. I know I can take this thing apart but I am not so sure I can put it back together. I did go out and buy a good socket set and some torque wrenches, Mercury shop manual, but I am afraid of missing something or doing some thing wrong and trashing my engine when I first start it up. What do you guys think is it work the risk? I must say I have learned alot just by taking it apart so far.

Sorry for the long post and thanks for your help. :joyous:
 
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