200HP Merc EFI seized??

[blackboat]

It looks like most of the piston break has been there for a while.Did you find most or all of the pieces? In the pics,the bore does look pretty good.You're really lucky in that respect.One would expect to see some really deep vertical grooves in that situation.

[JOE54]

somebody prob dropped it one time or another didn't see crack, very very lucky

[Sputs10]

Thanks again! I believe I got an exact replacement piston from WSM. I bought a new connecting rod and all new gaskets and hoses from teardown. I also bought a flexhone by recommendation from a machinist here at work to rehone the cylinder before installing the new piston.

Thanks for all the help. I'll update once the parts come in.

[Sputs10]

Here is a photo of a hairline crack in the piston that I found. It may be tough to see in the picture, but it's there.

Do you guys think that after I rehone the cylinder I should be able to reinstall with all new parts? I've ordered the grease and all necessary gaskets.

Thanks again!

[EuropeanAM]

Really no way to answer that question without hands-on inspection of the cylinder itself.

[lpugh]

Unless you have that motor completely tore down for proper cleaning I would pass on the honing, The honing will embed small particles of the stones that can create a wear factor that is unbelievable. I have seen motors totally worn out in 30 hours of use when done this way, it can be done but it takes a lot of precautions, would not recommend this approach for most people. Far less risk if you skip the honing. Not taking anything away from what Joe said, He knows far more about these motors than I do. I am a automotive tech that just has some experience with mercurys. just sometimes we forget and make assumptions on do it your selfers ability's
Also after seeing that I would want to inspect every thing in that motor, and check the ports carefully as they need a little attention to prevent a repeat

[JOE54]

exactly why I would NOT have done it that way my shop got torn down all new rings , why I said good luck

[Sputs10]

I apologize for my ignorance. I'm not looking for the easy way out. The guy that made the suggestion said to block off all of the ports and just make a few passes with oil on the cylinder walls. I didn't intend to spend more than 30 seconds inside the cylinder. But again, I've never done anything like this, but I'm a fairly mechanical person. He did say that it would make an oil slurry inside the cylinder that I'd have to clean thoroughly. All that being said, this guy has rebuilt several car motors, but never an outboard. I will take the advice of you guys.

When you say "proper cleaning" or "thoroughly inspect", would you mind being more specific? I don't have the means to remove the powerhead, but is there anything you guys would recommend without separating the head? I don't mind pulling all 6 pistons and replacing with new parts.

Honestly, I'm just really enjoying doing this myself.

Thanks again guys!

[JOE54]

needs to be disassembled and inspect all clys for more bird dookey all honed and new rings on all at a minimum, bores sizes recorded bearings replaced possibly, fiber reeds , gasket kit ,and sealer, block washed thoroughly with hot soapy water in all cyls twice and rinsed clean then oiled ,no rust,id start with bare block and go from there, enjoy.....ps; find a reputable machine shop have block mic for wear and bored .010 more

[lpugh]

^^^^^^^^

"block washed thoroughly with hot soapy water in all cyls twice and rinsed clean then oiled ,no rust,id start with bare block"

[Sputs10]

Yikes... may need to either look into a Powerhead stand or clean/inspect everything I can and hope for the best. When it fails again, I’ll be looking for either someone to ship it to, or replace with new. You guys have me intimidated and I wouldn’t trust Blackbird with my lawnmower engine.

With this motor, I will try to do as much as I can without removing the head. I’ll pull the pistons, inspect the bearings, and replace the rings at a minimum.

Thanks for your help guys!

[JOE54]

SPUT my opinion if ya gonna do that just put one in it and go on,see ya JOE

[Savage]

Blackbird is a shoemaker machinist......he buys junk from other Dealers scrap piles and throws together a bunch of mismatched used parts, then sells as rebuilt.

[Sputs10]

All, quick update and another question... I managed to reassemble the motor and it started within 2 cranks of the starter. I then took the boat to a local river, started the motor and drove around just above idle. Just enough throttle to move the boat. So from a functional standpoint, I'm extremely happy that I even managed to get this far.

My plan is to check compression and scope out the cylinder for any damage. I'm expecting the compression to be a little lower until the new rings seat, but just want to get an idea where I'm at.

My question is... What is the proper break in procedure for 1 cylinder? I've heard before that I should idle for 4 hours, and then run 2-3,000 rpm's for awhile, and so forth... but just looking for an experts take on this.

Thanks again guys! The support here is the best!

[EuropeanAM]

My question is... What is the proper break in procedure for 1 cylinder? I've heard before that I should idle for 4 hours, and then run 2-3,000 rpm's for awhile, and so forth... but just looking for an experts take on this.

I would NOT use that procedure. A little extra oil in the first tank (perhaps 100:1 on top of the oil injection), make sure the engine is up to operating temps, and run the engine 1/2-3/4 throttle range for the first hour or two. Avoid extended operation at any set RPM for the first few hours.

Essentially the same as a new engine... but there is no "book" answer for the situation.

[Sputs10]

Don,

First, thanks for your time and info. My motor isn't oil injected as Blackbird removes the oil pump as part of their 1 year warranty... at least this is what they told me. So, I've been mixing my oil 50:1. So, should I burn the first tank 25:1, or similar?

[wbh1954]

I can't believe it didn't get that Hole

[EuropeanAM]

Perhaps 40:1 for the first tank (I would not mix any more than 40:1).