Direction/advice needed...thanks in advance.

[bleubeans]

Okay, i just picked up a 94' 16' Starcraft Fishmaster with a 2004 50 hp Johnson. However, the motor is "locked up". I have been told that a power head from a 1981-89' and a few others will replace it. My buddy happens to have a 1984 Johnson/evinrude power head that he says runs but there is a crack in the intake manifold (he offered it to me for free). I am not experienced with rebuilding outboards but i am somewhat mechanically inclined. Therefore, my question is..can i simply replace the new power head with the older with no issues? I have not taken the newer motor apart yet. Is it possible that i might need to just bore the cylinders and get larger pistons? It was not my outboard when it froze up but i was told it "always ran great....then one day when it was being flushed it just shut off and that was it". The top cylinder has signs of what i guess to be "metal"...looks almost like corrosion....same thing on that cylinders spark plug. The lower cylinder looks fine from my inexperienced eyes and its plug looks like it should. I have been told i can part the 04' out. Which direction should i go? What first? If my friends power head is a direct bolt on.....wouldn't that be the best path? Thanks in advance, Bleubeans.

 

[bleubeans]

Re: Direction/advice needed...thanks in advance.

bump

 

[hidef]

Re: Direction/advice needed...thanks in advance.

I don't think the powerhead from the 1984 will fit but that doesn't mean you can't try. I would get the OMC service manuals for both outboards. You can get them at www.marineengine.com If you can't rebuild the 2004 you could part it out and what money you make from it you could put towards your boat and fixing the 1984.

 

[jbjennings]

Re: Direction/advice needed...thanks in advance.

THinking of the corrosion that you mentioned, it's easily possible that the crank and bearings are corroded as well, making it overly expensive to rebuild. A replacement used powerhead would probably be the best route, the better one probably being to part it out and look for a good used outboard. You might check the block #'s at the online parts diagrams on crowleymarine.com, but I doubt that everthing will match up perfectly that many years apart, even though they didn't seem to make a lot of big changes on the 50hp motors. If the #'s don't match.......
Then again, since your powerhead is toast, take it off and see if the mounting bosses and such are the same as your friend's block. If so, I don't see why it wouldn't work. Then again, maybe the mounting bosses for the shift linkages and such are different. I'd expect that might be the case. If you have access to both, check them out and see. Better than parts diagrams!!!
JMO,
JBJ

 

[bleubeans]

Re: Direction/advice needed...thanks in advance.

Well I had a few minutes of free time so i removed the head from the 04' and the what i was seeing was the piston "aluminum debris". The flywheel would move back and forth just slightly so i carefully removed the shrapnel and liberally applied wd-40 and i got the engine to turn over completely. This is good news correct? When i tear it down completely to inspect the crank, bearings, push rods, etc..what do i look for? As i mentioned before i am not a mechanic so when i disassemble the motor is there a smart way? Can i do this without screwing with timing later? Is the flywheel on a certain way that it should not be removed/replaced differently? Where can i find literature to assist me? I would really like to tackle this by myself for a learning experience. So, anyone out there with step by step instructions would be appreciated . I apologize for all the questions... Thanks again.

 

[hidef]

Re: Direction/advice needed...thanks in advance.

As I said earlier you will need the OMC Service manual. The manual will tell you how to disassemble everything and how to put it back together again. When you do get torn down you want to see where the metal came from as those parts will need to be replaced. The manual will also have the proper torq specs for re-assembly. Good luck

 

[RogersJetboat454]

Re: Direction/advice needed...thanks in advance.

Okay, i just picked up a 94' 16' Starcraft Fishmaster with a 2004 50 hp Johnson. However, the motor is "locked up". I have been told that a power head from a 1981-89' and a few others will replace it. My buddy happens to have a 1984 Johnson/evinrude power head that he says runs but there is a crack in the intake manifold (he offered it to me for free). I am not experienced with rebuilding outboards but i am somewhat mechanically inclined. Therefore, my question is..can i simply replace the new power head with the older with no issues? I have not taken the newer motor apart yet. Is it possible that i might need to just bore the cylinders and get larger pistons? It was not my outboard when it froze up but i was told it "always ran great....then one day when it was being flushed it just shut off and that was it". The top cylinder has signs of what i guess to be "metal"...looks almost like corrosion....same thing on that cylinders spark plug. The lower cylinder looks fine from my inexperienced eyes and its plug looks like it should. I have been told i can part the 04' out. Which direction should i go? What first? If my friends power head is a direct bolt on.....wouldn't that be the best path? Thanks in advance, Bleubeans.

If you look at the BRP website parts diagram, the part numbers for the 2 cylinder 50's (assuming your '04 50 isn't a 3 cylinder) between '84 and '04 changes. Makes you wonder what the diffrence would be. I think a 20 year diffrence would make this swap dicey to say the least. The powerhead may bolt to the intermediate housing but what else needs to be sorted out or fudged to make it work? Keep in mind you are essentially dealing with 2 diffrent manufacturers too. OMC for the '84, BRP for the '04.
If you want to rip apart what you have, I suggest getting a BRP factory service manual.

 

[bleubeans]

Re: Direction/advice needed...thanks in advance.

If you look at the BRP website parts diagram, the part numbers for the 2 cylinder 50's (assuming your '04 50 isn't a 3 cylinder) between '84 and '04 changes. Makes you wonder what the diffrence would be. I think a 20 year diffrence would make this swap dicey to say the least. The powerhead may bolt to the intermediate housing but what else needs to be sorted out or fudged to make it work? Keep in mind you are essentially dealing with 2 diffrent manufacturers too. OMC for the '84, BRP for the '04.
If you want to rip apart what you have, I suggest getting a BRP factory service manual.

I have sort of dropped the idea of installing the 84' power head on it after comparing the two. I am thinking about rebuilding the 04' or at least having it bored with new pistons, rings etc. What other cost should i expect? Can i disassemble it and drop it off to be bored and just order new pistons, rings etc?

 

[RogersJetboat454]

Re: Direction/advice needed...thanks in advance.

I have sort of dropped the idea of installing the 84' power head on it after comparing the two. I am thinking about rebuilding the 04' or at least having it bored with new pistons, rings etc. What other cost should i expect? Can i disassemble it and drop it off to be bored and just order new pistons, rings etc?

You really need to pull it all apart to figure out if anything else may be damaged aside from the piston you found beat up. No telling what the cost would be to rebuild this untill you have that info.

 

[bleubeans]

Re: Direction/advice needed...thanks in advance.

You really need to pull it all apart to figure out if anything else may be damaged aside from the piston you found beat up. No telling what the cost would be to rebuild this untill you have that info.

Yeah i figured that. Any suggestions on disassembly? Is there a certain way (until i get the manual) i should take it apart which would make it easier when i start to reaassemble? Sorry if thats a stupid question but i haven't tangled with one of these before and i figure someone with experience can donate some knowledge/suggestions...lol. Is it possible that i won't need anything but a piston and rings??? or is that wishful thinking? I know i won't know until it's apart but is there a possibility? I'm gonna try and tear it down this afternoon. Power head is off.

 

[RogersJetboat454]

Re: Direction/advice needed...thanks in advance.

Yeah i figured that. Any suggestions on disassembly? Is there a certain way (until i get the manual) i should take it apart which would make it easier when i start to reaassemble? Sorry if thats a stupid question but i haven't tangled with one of these before and i figure someone with experience can donate some knowledge/suggestions...lol. Is it possible that i won't need anything but a piston and rings??? or is that wishful thinking? I know i won't know until it's apart but is there a possibility? I'm gonna try and tear it down this afternoon. Power head is off.
View attachment 92424View attachment 92422View attachment 92423

Lots of pictures of how everything goes. Get zip lock bags an label them for the specific nuts bolts screws and little bits and pieces you pull off. Make sure this all happens in a really clean environment. It may be possible that all you need is a piston and rings, but to tell you the truth, what you have is pretty ugly looking, and I wouldn't be surprised if you found more carnage while digging. You also need to determine why that happened so it doesn't happen again.

 

[bleubeans]

Re: Direction/advice needed...thanks in advance.

Lots of pictures of how everything goes. Get zip lock bags an label them for the specific nuts bolts screws and little bits and pieces you pull off. Make sure this all happens in a really clean environment. It may be possible that all you need is a piston and rings, but to tell you the truth, what you have is pretty ugly looking, and I wouldn't be surprised if you found more carnage while digging. You also need to determine why that happened so it doesn't happen again.

I got the engine torn down yesterday (See pics). Everything looks very clean inside and i don't see and more carnage. I don't have the socket/tool to remove the push rod caps (i guess that's what they are called) but looking at the push rods, bearings, crank etc ....everything appears in amazingly good condition. It's hard to tell but the cylinder walls aren't as bad as the pictures make them. I mean there is a thin layer of the melted piston skirt that can be tediously picked at and comes off in small sheets. I just don't want to damage/scar the walls anymore than they already are.Underneath the cylinder looks good still. I know this prolly don't mean squat but i still got my fingers crossed.

 

[RogersJetboat454]

Re: Direction/advice needed...thanks in advance.

I got the engine torn down yesterday (See pics). Everything looks very clean inside and i don't see and more carnage. I don't have the socket/tool to remove the push rod caps (i guess that's what they are called) but looking at the push rods, bearings, crank etc ....everything appears in amazingly good condition. It's hard to tell but the cylinder walls aren't as bad as the pictures make them. I mean there is a thin layer of the melted piston skirt that can be tediously picked at and comes off in small sheets. I just don't want to damage/scar the walls anymore than they already are.Underneath the cylinder looks good still. I know this prolly don't mean squat but i still got my fingers crossed.

I think by "push rod caps" you mean connecting rod caps? The bolt heads look like a 12 point socket will do the trick. If you are going to take it apart any further make sure you mark which cap goes to which rod and in which direction. The caps are machined to the rods so you must not mix them up or put them on back wards. Hopefully some one else with more O/B rebuilding experience will chime in (I'm no expert on O/B repair), but by the look of your rod bearing caps (discolored/ brown), it appears that they may have gotten hot and burnt the oil on them. That would mean bad news for the crank and possibly the rods.

 

[ONERCBOATER]

Re: Direction/advice needed...thanks in advance.

some discoloration can be expected from a life in a bath of two stroke oil but it should come off with no effort if it looks cooked on you likely have issues, I couldn't tell from the pics. I read a long article about connecting rods and how they are made and why it is so very critical to maintain the caps and the rods both in correct orientation and with ea other. NO TWO ARE THE SAME EVER remember that, I personally mark them with a scribe before removing them and then put ea pair in a zippy bag by it's self.

(edit,) the normal discoloration i was referring to would be all over the rod not just at one end (end edit.)

 

[bleubeans]

Re: Direction/advice needed...thanks in advance.

Okay, well i think i may have screwed up. I had made it a point to keep the correct cap with it's connecting rod. However, i should have put the bolts back in their holes to keep everything together. Instead i placed them on my workbench separately and....well....long story short i am not 100% sure each cap is with the right rod . (sorry, i was calling them push rods earlier....)
Is there a way to be sure after-wards? Please don't tell me i have to get new rods/caps:facepalm:. I should have marked them. In any case, I forgot to ask about the head. My question is: Does it need to be replaced?(looks great) Could it be warped and is there a way to tell? I went ahead and dropped the lower unit to inspect the water pump and it wasn't ripped/melted....actually looked good. Should i continue to inspect the water passages? Why would the top piston burn up and the lower is like new? Could it be from running "lean"? I just assumed it was not getting water up to the top cylinder therefore, it overheated and melted the piston.

BTW- there is no discoloration anywhere. The pics aren't that good sorry. The paint is still on most everywhere.

 

[daselbee]

Re: Direction/advice needed...thanks in advance.

Your engine looks very good from the pics, except for the burned top of that piston.

You know how if you break a china plate into two pieces? You can actually fit that plate together almost perfectly with a barely visible line? Damn near perfect?

Well same with the rods. Fit a cap to a rod by hand, and work it until it fits perfectly. Turn the cap around and try the fit. If it won't go back where all the beveled corners are absolutely perfect, chances are it is the wrong cap. Try another. You will eventually get them back matching.

When re-assembling, this rod cap fitting is EXTREMELY critical. If you put one on without match fitting it, you will destroy the roller bearing, throw the rod, ruin the crank, and generally destroy the motor.

Rods are supposed to be copper brown in color. Look at the rod roller bearing surface. It should not be burned, blue, or otherwise scored.

Yes that top piston looks like is was run lean. The carb feeding that cylinder is suspect and should be looked at very carefully.
Clogged high speed jet (or the complete high speed circuit in the carb) is the most likely culprit.

 

[bleubeans]

Re: Direction/advice needed...thanks in advance.

Your engine looks very good from the pics, except for the burned top of that piston.

You know how if you break a china plate into two pieces? You can actually fit that plate together almost perfectly with a barely visible line? Damn near perfect?

Well same with the rods. Fit a cap to a rod by hand, and work it until it fits perfectly. Turn the cap around and try the fit. If it won't go back where all the beveled corners are absolutely perfect, chances are it is the wrong cap. Try another. You will eventually get them back matching.

When re-assembling, this rod cap fitting is EXTREMELY critical. If you put one on without match fitting it, you will destroy the roller bearing, throw the rod, ruin the crank, and generally destroy the motor.

Rods are supposed to be copper brown in color. Look at the rod roller bearing surface. It should not be burned, blue, or otherwise scored.

Yes that top piston looks like is was run lean. The carb feeding that cylinder is suspect and should be looked at very carefully.
Clogged high speed jet (or the complete high speed circuit in the carb) is the most likely culprit.

Thanks, daselbee....i was just looking at the rods/caps and realized that. It's like a puzzle. They are together correctly.
I broke both carbs down and man...i gotta tell ya...I have never seen a cleaner set of carbs. Not so much as a spec of dirt or even fuel resideu for that matter... I can see through all the jets. I will go ahead and go through the motions anyhow in case there's something I can't see. I will post more when i find the culprit.
The place on the connecting rods where the bearings ride on the wrist pin (or vice versa?) is shiny and shows no scars or signs of heat.
I think I'm gonna drop it off at the machine shop (marine) to get it bored tomorrow. Is that how it is done? Can just one cylinder (the top #1 in my my case) be bored out and use a piston one size up (whatever that is) while the lower (#2) cylinder maintains a stock piston? This doesn't cause a balance issue? Seems as if 0ne piston is larger it will weigh more?? Maybe the weight is still the same??? I ask because the shop told me that's what they will do. He said "he will bore not hone because 9 times out of 10 the cylinder is out of round (ovaled or egged)" This is of course after measurements but he said with his experience that will be the case. Can I order a single oversized piston and rings myself? I was told "probably not". If I can save a buck...im game...but I don't wanna be cheap and not do something that i should while it's apart. For instance, the crank bearings, rod bearings, etc... should i just go ahead and replace just because im in there? Keep in mind ...im poor...lol. Any other recommendations?

Seloc repair manual is on it's way. I hope it's instructions are clear and make sense to an inexperienced person like myself.

 

[hidef]

Re: Direction/advice needed...thanks in advance.

Do yourself a favor order the BRP Service Manual you can get it at www.marineengine.com. The Seloc and Clymers are not very good.

 

[beagleboy]

Re: Direction/advice needed...thanks in advance.

You need a re-bore on BOTH cylinder. You must get new pistons first. Machine shop will need them to measure to see what to bore down to thousands of an inch plus clearance. Your problem in my opinion is what I call a lean melt down. There are other issues you must address or you will cook the new pistons. Water or stale gas is a possible issue. Before buying pistons take the jug to the machine shop to see what over size you need. Both pistons need to be replaced because of a balance issue.

 

[daselbee]

Re: Direction/advice needed...thanks in advance.

If you are asking my opinion....yes you can do one cylinder. Leave the other as is.
The shop saying out of round....I don't know about that one. As clean as that engine looks, it probably is just scuffed and needs boring due to the cyl scratches. Ask them to measure it while you are there. Look at the numbers they measure. It only takes a few mins.
That engine looks clean as a whistle, and I wouldn't hesitate to re-build it based on the pics you posted. I think that was a good call on your part.

It is important to have a shop that is well familiar with boring outboards. The boring block is different in that it needs to be able to bore a "blind hole". This is a cylinder bore that has metal at the bottom that the boring bar cannot pass by. Look in there. You will see where the rod comes up from the crank thru a slot, and no boring machine can go past that slot. That is a "blind hole". Needs a boring bar that can go to the bottom of that hole.

Any way it is, tho, you need to bore to oversize, probably due to cyl scratching and aluminum transfer from the piston to the cyl wall.
The piston and ring SET should probably cost you no more than 70 bucks or so. That is aftermarket. If you go BRP, it will be more. Look it up on shop.evinrude.com to get an idea before you turn the shop guys loose with your wallet. (Just an estimate based on buying V6 looper pistons.)

FIND OUT what caused the failure, or it will happen again.