Separating a power head

[belray]

I need some advise from you guys, especially from the experienced outboard techs. I have a 1987 Mercury Black Max 200 hp and burned up the number 2 piston at the end of last season. I'm trying to separate the power head. I have everything disconnected and all of the nuts removed from the studs but this thing is stuck. I have the engine hoist pulling up on the engine and prying everywhere I can to no avail. How do you guys separate the power head with minimal damage? I am sure that the long studs are corroded and holding it all together. I'm not a boat mechanic but am an auto mechanic for 35 years so I know I can fix this thing if I can get the power head separated. I have to. My wife is using this as an excuse to buy a new boat but I don't want the payments. Thanks for any advise.

 

[merc850]

I have found that the gasket between the powerhead and exhaust extension can "weld" the 2 together, I use a kitchen knife and drive it between them, go all the way around and it should let go.

 

[Dukedog]

10 nuts?

most older V6's that have never been touched and/or salt, heavy mineral water motors this is gonna be tha case... you will hear a variety of remedies but most end up drilling thru and /or sawzall tha studs thru tha adapter plate (will need ta be replaced) to separate... driving anything between tha plates and power head usually doesn't end well with block surface...

 

[belray]

Thanks for the advise. I saw a YouTube video where the guy had to drill through the studs and I was hoping not to have to do that but will if I have to. I'm going to haul the boat up to work again this Saturday and take another bite at the apple. Where do you guys get your engine parts? Do you get everything from iboats? I have shopped around on the net and some parts are showing "unavailable" though I'm sure parts for these engines are around.

 

[DouglasW]

... My wife is using this as an excuse to buy a new boat

OMG!!! Are you kidding, that is a boater's dream come true. Does she have a single sister???

 

[racerone]

Is there room to put something UNDER the studs?----Then use the nuts to push up on the studs ?

 

[dawwgman]

I've used this many times. Heat! do not do this unless you have cleaned the engine of all gas or oil. Using a small propane torch heat the stud area. The steel, corrosion and aluminum expand and contract at different rates and will cause a crack in the corrosion. then apply penetrating oil. Be sure it has no gas or oil on the engine.

 

[belray]

Thanks for all of the advise guys. I really appreciate it. I took my boat to work last Saturday and tried everything but ended up drilling the studs like dukedog suggested. I finally got the power head off and stripped it down. The number 2 piston had a meltdown and shared it's aluminum with the cylinder. There are tiny pin holes in all of the cylinder linings and a pitted rod bearing on cylinder 4 with damage to the crankshaft. I have been told that these crankshafts cannot be machined like auto crankshafts and as I add up the needed parts and machine work to the block, I think this repair will exceed a reasonable cost to repair it as my boat and motor is 32 years old. So, I'm looking for a good running used engine but I have no idea how to determine the value of a used outboard engine. There are some online that have "been professionally rebuilt with new rings, gaskets, carb overhaul" etc... but there is no way of knowing what's inside and how it will run under load. I know it's going to cost some money to get this thing back on the water but I would rather fix it and enjoy it for a couple of seasons without a boat payment if possible. But come this summer, I need to be on the water one way or the other because I love boating.

 

[racerone]

A rebuilt powerhead is a good option.-----Many available

 

[belray]

Where can I find one? I have googled remanufactured power heads but haven't found one for a motor this old. 1987, OB184641. When I put in the serial number I get a message that they have no match for that number.I'd love to get a hold of a reman power head. Pop that baby on and be back in business.

 

[Dukedog]

what do tha cylinders look like "other" than tha pin holes?.. pin holes are normal with chrome bore mercs and actually add a coolin' effect on tha cylinder.....

 

[belray]

Number 2 piston had a complete meltdown and that cylinder has melted piston attached to it. I burned up a piston 30 years ago on my stand up jetski and had took the block to a boat and motorcycle mechanic and he cleaned it up with muriatic acid, honed it, and I replaced the piston and rings and got another couple of summers out of it before I sold it. I was hoping for the same with this engine but the crank has damage to a journal, some of the bearings are bad and the head on that cylinder is beat all to hell. I started pricing out the parts and the cost is quickly getting up to the point that I may need to look at other options.