1999 200 EFI powerhead rebuild 2024

Dam Yankee reply :

I was wondering if anyone here has rebuilt one of these and if it was more cost effective to do so rather than buying one already rebuilt.

Way2slow reply :

It's only cost effective if you have built a number of two stroke outboards and know what you're doing. There's a lot of little things you need to know that you don't do with car motors.

If it broke, and not just worn out, then you have to know how to read the signs the internal parts are giving you as to why it broke. Very good chance the ECM, the injection system or oiling system caused the failure and if you don't find what caused it to break, you will probably be doing it all over again in short time.

An experienced guy doing it himself can save a few thousand. An inexperienced guy doing it himself can cost himself a few extra few thousand or even a whole motor because if it damages the block or crank, they will give you very little or no core credit on it.

Dam Yankee reply :

Good advice. I have been turning wrenches my whole life. Confident I can handle it. Initially by looking at the plugs I have one cylinder that is effected. My first guess is that an injector failed. I could be wrong though.

Way2slow reply :

From the looks of that one plug, looks like you melted a piston.

You didn't say what make motor. Is it an EFI or DFI motor. I think the only injectors in an EFI is up in the air horn. If thats the case, an injector failure should have affected more than just one hole. If it's DFI, then it's possilble to have been an injector.

Bad/old gas can cause it, ignition can cause it (one cylinder can be advanced too much).

Air leak somewhere.

Depends on what the dome of the piston looks like.

Dam Yankee reply :

True. It is an EFI not DFI. It was runnin a little rough that day at low idle thinking back on it. One other thing also. I noticed a lot of dirt. It seems that some mud dobbers had gotten into the top cowl vent and it is blown all over the inside. Not good. The fuel had 1/2 tank of 3 week old gas and I topped it off that morning. I do use seafoam regularly in the tank but didn't on this last fill up. Got most of everything off of the powerhead except for the fuel system. Probably have that off and the unit off tomorrow. Anxious to figure out the problem.

Way2slow reply :

I would have just popped the heads off first and seen what the piston and cylinder looked like.

As for the tear down, it would be much simpler just to pull the whole powerhead off and put it on and engine stand. It's going to have to come off anyway before you can do anthing with splitting the case and getting the pistons/rods and crank out.

Once you get the head off, take some good picks and and ask the merc experts (I'm assuming it is a merc) on Scream and Fly technical forum about what they think caused the melt down. There's a whole bunch of merc racers and engine builders on there that have seen every kind of melt down one can give you. They can probably give you a good idea of what caused it. Lean will usually burn/melt it toward the exhaust port. Pre-Dedonation will usually leave pitts around the edges of the piston along with a hole in the center. Timing/double fire will usually just take the center right out of the piston (bad ecm).

fishfordollars reply :

X2 on the above post. Just rebuilding the powerhead won't do it. You must find/fix the problem that caused the failure.

Dam Yankee reply :

Exactly. I popped the heads off this morning and posted where a mercury tech can see em and help with diagnosis. Will know more when I get a look at the wrist pin bearings for #6. If they are intact then it is a possible cold seizure scenario. It also appears that WOT timing screw was way advanced by what he saw in a photo. I Also found the Idle stabilizer advance/detonation control module red/wht stripe wire was hanging loose inside. So three possible scenarios. He is a very reputable tech and I am lucky to have his input. Damage on 2 and 4 also. I have had this for almost a year and never knew this or had a problem except for a rough idle. Just goes to show don't let little things fester. Expensive lesson. On stand now and will get into it some more next weekend.

toolpush reply :

Been there, done that. $4800 rebuild,reputable mechanic.

Way2slow reply :

I would strongly recommend you take good, fairly close pics of each piston and post them here http://www.screamandfly.com/forumdisplay.php?20-Technical-Discussion. There are some mighty good merc guru's on that site. From the way these look, that top piston was a little lean. It looks to me like the bottom piston was lean, and kept melting away piston until some of the rings or locator pins got sucked up on top of it.

You will probably need to replace that head also. That is also a good site for merc parts. Just be careful buying heads, most of those guys are racers and hotrodders and some are not above selling you a cut/shaved head. You will want a stock, that has not been cut.

One other word of caution. Soooo many people think that since they are rebuilding it, this would be a good time to throw in some mods. DON'T get tempted. While there are a few things you can do, the most hp gains come from porting. This has to be done by an experienced person, and YOU WILL screw up your first block if you think you want to try it yourself. I screwed up my first five or six in one way or another before I got it right.

Another thing you have to remember, Mercs are 2.4L/2.5L motors and the factory didn't leave a whole lot of power on the tabel like they did the 3.0 OMC's (my motors). They do crank out very good hp, but the only way to get big hp numbers is by increasing the rpm through changing the port map. As you increase rpm you take away hole shot. Something that does not work real on heavy bass boats. The second downside to that is you have to really know how to tune a two stroke because you will greatly increase you're chances of melting it down again.

fishn hard reply :

Quote
I would strongly recommend you take good, fairly close pics of each piston and post them here http://www.screamandfly.com/forumdisplay.php?20-Technical-Discussion. There are some mighty good merc guru's on that site. From the way these look, that top piston was a little lean. It looks to me like the bottom piston was lean, and kept melting away piston until some of the rings or locator pins got sucked up on top of it.
You will probably need to replace that head also. That is also a good site for merc parts. Just be careful buying heads, most of those guys are racers and hotrodders and some are not above selling you a cut/shaved head. You will want a stock, that has not been cut.

One other word of caution. Soooo many people think that since they are rebuilding it, this would be a good time to throw in some mods. DON'T get tempted. While there are a few things you can do, the most hp gains come from porting. This has to be done by an experienced person, and YOU WILL screw up your first block if you think you want to try it yourself. I screwed up my first five or six in one way or another before I got it right.

Another thing you have to remember, Mercs are 2.4L/2.5L motors and the factory didn't leave a whole lot of power on the tabel like they did the 3.0 OMC's (my motors). They do crank out very good hp, but the only way to get big hp numbers is by increasing the rpm through changing the port map. As you increase rpm you take away hole shot. Something that does not work real on heavy bass boats. The second downside to that is you have to really know how to tune a two stroke because you will greatly increase you're chances of melting it down again.

I would listen to every thing way2slow says he hit the nail on the head with this post there is alot of of good info on screamandfly but dont get caught up in the all the BS over there if you want a phone number of a great guy to fix your motor and not bend you over the stump let me know his name is Texas00225 on screamandfly Mr Bobby he lives in Texas let me know i can hook you up with him he is a great guy I build motors but only mine and my brothers if you want to try it your self you can do it you will just need to send the block off and have a new sleeve put in it let us know if we can help

Dam Yankee reply :

I do appreciate all the advice. This forum always seems to have folks willing to help with advice and whatever folks need. Hopefully when I get this done I can help others. I am a very experienced mechanic. Just never did an outboard. I will take it slow and read everything thoroughly for sure. Never paid a mechanic to do anything before and everyone I know would be very surprised if I had somebody do it for me. Right now my thoughts are going towrds where to find a reputable machine shop with outboard experience to verify all my measurements and reccomend what needs to be done. The teardown of the bottom end will also give me some more clues to complete the picture of why this motor failed. I will get some good pics of the pistons and cylinder walls and post em up when I get there this weekend. Hopefully by Monday I will be able to take it to a machine shop.

Not looking to modify anything although the thought did cross my mind. (But this is not a buick GN!) At this point the only thing I am considering is to eliminate the oil injection system and get this thing done correctly the first time as 65 to 70 is fast enough for me on the water.

Thanks again everyone for your advice. Trust me, I am listening.

Way2slow reply :

You MUST have it bored by a shop very experienced with outboard blocks. Every hole I've ever had a good auto machine shop bore was screwed up. They can't do it. Most can't because they don't have the head to bore blind holes. Those that try almost always leave the sleeve with a tapper. On top of that, many are ungodly expensive that do try. Plan on shipping the block off and it should only cost you between $200 and $300 to bore plus shipping. I know of a great shop in Tennesse, but they are whole sale only, nothing for the public. Some of the guys on S&F may be able to tell you of someone close to you. Maybe someone on here knows of a place close to you. Again, DO NOT take it to an auto machine shop.

One other thing, after final honing, the edges of the ports must be chamfered so the rings won't bite the sharp edge of the port and break the rings. No non marine machine shop would know how or even that it needs to be done.

fishfordollars reply :

Again he is right on. A competent employee of an auto machine shop can/will screw up an outboard block.

Dam Yankee reply :

It is like you guys are reading my mind. I definitely do not want to take it to someone who has no outboard machining experience. Seems like there should be someone around here somewhere. Toledo bend has a lot of fishermen and I am sure somebody around here does this work or has it sent somewhere reputable. Actually while reading I had already decided that I do not even want to put the crosshatch on the cylinder walls but I do want to do the complete assy of everything. The crosshatch seems to be a critical part of proper oiling but that is down the road a bit. There are a lot of particulars about this that I am just now beginning to get familiar with. A good book helps. I read about the taper by the ports also and definitely don't want anyone learning at my expense.

I know it probably sounds funny but, even though I would rather be fishing (which I suck at but enjoy) I am looking forward to doing this almost as much as if I were getting up to go fishing! Looks like if I wanna go fishing I am gonna have to hitch a ride for a while!

fishn hard reply :

I would strip down the block and heads and send them to Outback Outboards in Augusta Georgia Mike Clemons I got his number he does all my block work and he can fix that bad head.and my injectors would go to razorback marine and the ecu would go to Tonie Brucato he can tell you whats wrong and if its bad he can hook you up with one of his PCU and let me say i have one and they are the stuff. mike Clemons can tell you every thing you need and get you the right parts and wile i had it down i would find a set of 4pettal rubber coated reed cages and put in it and a set of Chris Carson reeds in it take that vapor can off the side and put it in the trash and move your fuel pump in the boat and all of that pre detonation modules junk would go in the trash also and set your timing 0deg @ideal and 24deg @WOT if you need any help let me know

fishfordollars reply :

Man, i thought he wanted to just fix his powerhead and get back on the water. Could of fooled me though.

Dam Yankee reply :

Quote
Man, i thought he wanted to just fix his powerhead and get back on the water. Could of fooled me though.

Trust me You are right Jack. I do want to get back out there. I did have thoughts of what else should be done while it is down and getting the injectors flowed and checked is an excellent example of something to consider while in it's present state of disrepair. I am open to any good ideas short of modifying the motor that would be a mechanicly logical step in a longer lasting and more reliable motor.

fishn hard reply :

Quote
Man, i thought he wanted to just fix his powerhead and get back on the water. Could of fooled me though.

He isn't put that motor back on the water unless he gets a new sleeve put in that motor from the looks of the pic it will take more then 30thousands to clean up that hole and if 30 would clean it up alot of guys dont want to go that big on a efi motor because the heat number 6 is your hottest hole on the 2.5 and as far as the injectors being sent off and flowed thats a must and the ecu that's a must also a lot of guys don't know if that ecu is the A17 box it is lean around 5200 RPMs and that's the range we like to cruse our boats at every thing ive said about sending off is just part of the rebuild whether you do it your self or not

fishfordollars reply :

you have a ride here. sent you a pm.

Dam Yankee reply :

Quote
you have a ride here. sent you a pm.

Thanks Jack! Anytime you come to the bend I will be willing to go with you. Hell, even if my boat was up and runnin I would go with ya! Always ready to learn from others and meet new folks.

CCP reply :

Dam Yankee, if you do send it to some........I recommend Nichols outboard engineering.

http://www.nicholsoutboard.com/

Just give Paul a call and talk to him. I can assure you that it will be right when it leaves his shop. They will find out what caused the failure. To me it looks like a locater pin came out but that is just guessing from the photos. I think you should be about to get the engine built for about $2500

Dam Yankee reply :

After some careful thought and deliberation I have decided to take it to a reputable person just north of Houston. It is within driving distance and the price is right. Very close to what it would cost doing it myself. He is going to do many of the things suggested here in this thread. Removal of oil injection, injectors flowed and tested by Brucato,Ecm checked, New Carson reeds, etc..

Cary from Mobile Marine. I do believe he hangs out on scream and fly and on texasfishingforum. I haven't been able to find anything negative and after talking to him I think he is a good choice. Plus I am eliminating the shipping. It is only a 3 hr. drive from here.

I appreciate all the input as it helped in making my decision easy.

fishn hard reply :

Cool that's a good choice but what i like about learning to do it your self is that after its done you understand the motor more then what you do now and it makes it much easier to diagnose problems if you need any thing let me know

Dam Yankee reply :

That is actually the downside for me for reasons you stated. I would like to do it myself too however, what I ballparked to do it myself was right around what he is doing it for freeing me up to do other things that I have been putting off. I still can't believe I am letting someone else do it but, he is very reputable from what I have heard. Timed, broke in, 90 day warranty.

I couldn't pass it up.

Dam Yankee reply :

Got everything back together and I couldn't be more pleased. Took the boat out yesterday to run about 25 gals of a certain ratio mix and I was VERY impressed! I was at 68mph @5600 RPM. Lake was like glass.

Cary Ogden "the boat doctor" did a very good job. New Caney Tx. just north of Houston. Anyone in this area that needs a reputable quality outboard tech I highly reccomend him. fishfordollars (Jack, RIP) recomended him to me and it worked out great.

Complete rebuilt powerhead, Injectors and ECU sent off and checked, New reeds, Oil injection removed, etc... 90 day warranty.

fishn hard reply :

8-) 8-) 8-)

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1999 200 EFI powerhead rebuild 2024

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