90 ELPTO 2 Stroke Powerhead Install

[gydatree]

I am about to start a project installing a used powerhead to replace one that burned up its pistons, putting a whole in the bottom one, and was wondering if there were any particulars I should lookout for.

I am suspecting it had oil injection issues, so I was planning on setting it up for pre mix, and will test the impeller/water pump asap (Is there a way to do this before I put the powerhead on?).

I have new gaskets for the carbs, fuel pump, and the base around the bolts etc. Along with fuel pump, I was gonna clean the tank, maybe new lines etc.

My main questions are: I only have one gasket (pic attached) for the base connection. Is that the only one needed for the bottom of the powerhead? Should I grease the shaft connection or anything?

Should I anticipate any issues with the flywheel and shaft sizes matching up or anything?

Any other particulars that need to be done with that procedure besides just putting it on with the new gasket and bolting it down?

Any advice/suggestions would be greatly appreciated!

 

[Faztbullet]

Are the powerheads the same year??? Make sure the powerhead and adapter are scraped clean and use NO sealer. Torque the nuts to spec,replace the impeller anyway. Add a dab a grease to splines and post pic of damaged engine as oil injection failure wont burn a hole in piston,carb or ignition problem does this

 

[gydatree]

The replacement is a 2007, not sure about the old one at the moment but def the same model. Is the adapter something that wouldve come off with the old one? Are the splines where the rotating shafts connect from the powerhead into the mid section?

I will be going to get started later this afternoon, and can post pics of the old head then. Compression was solid in top two pistons even though they were scored a bit, with the bottom at a total loss of compression and a clear hole in the piston. Seemed like the Cylinders had sleeves added in already at some point.

If it were mine, I would go ahead and replace the stator, trigger, impeller etc, but im helping a friend out and i know hes not gonna wanna spend the $ to be proactive about it.

Thanks!

 

[racerone]

Motors come from the factory with cast iron sleeves when new.

 

[gydatree]

I am having issues uploading pics here, but here is a link to a pic of the piston with the hole in it. I took detailed pics of the other pistons, crank case and everything else, just cant upload them for some reason.

Seems like I could maybe replace the sleeves and pistons with rings/gaskets and it may be good to go. Going to take it to a machine shop soon and get their opinion.


https://drive.google.com/file/d/0BypCxGagxrSjeW9OUmdyMUY5Uzg/view?usp=drivesdk

 

[Silvertip]

Until you determine exactly what caused the burn-down, you run the risk of burning down a new or rebuilt engine. Overheating can cause a melt-down so make sure the thermostat and water pump impeller are replaced. Don't just install new gaskets in the carbs. They need to be removed, totally disassembled, every passage cleaned and then reassembled with new kit parts. Before you disassemble the carbs turn the adjustment screws while you count the turns in until lightly seated. That way you can reset them to the former settings after the rebuild. Those may or may not be the final settings. Carb adjustment is best done in the water -- not running on muffs. If oil injection was an issue the alarm should have sounded. The same alarm is used for overheat. If the alarm is not working, you have no indication of a problem. What did the spark plugs look like that you removed?

 

[gydatree]

Definitely planning on cleaning the carbs up real good with all new gaskets.

I put a link to a picture of the piston that lost conpression due to a hole in it in the thread above. The other two were scored a bit with broken rings, but both had good compression, not much visible damage to the crankcase. Going to take it to a machine shop soon and get their opinion.

The stator looks like an updated model and not the factory one. I took pics of everything but having trouble uploading.

Not sure how the plugs looked, but it did run, just didnt have compression in the bottom. Not sure if the oil alram was working or not either, was gonna just set it up for pre mix.

What part of the ignition system can cause damage to pistons? Can you tell what caused it by looking at the piston picture? Are you guys able to open it up (link in the thread above)?

 

[Silvertip]

The spark plugs could have given you an indication of what happened. "Reading" spark plugs is a diagnostic technique to help determine if the engine is running rich (oily black) , lean (whitish) or perfect (tan).The ignition system supplies spark to the plugs and alone does not and cannot cause that damage. Ignition TIMING can and often does cause pre-ignition that can kill and engine. I don't think that's the issue. This looks like lean fuel mixture. Lean fuel mixture also means lack of oil. When combined, the engine burns down. Your oil injection alarm had it been working would likely have prevented this. If it was an overheat condition, the alarm would have alerted you to the problem as well.

 

[gydatree]

Allright, so I cleaned the base mount and powerhead bottom and got the replacement powerhead mounted in with a new gasket and able to spin the prop. I am trying to wrap my head completely around the remaining setup with all the components etc before I start putting things on. I feel like I just about got it, but do have a few questions.

Going back to poasible causes of the initial piston failure: Today I cleaned and rebuilt the carbs and fuel pump with new gaskets etc. It did seem the bottom carb had the most wear on its gaskets etc, and the top one was still noticeably lubricated with fuel. You could see the fuel had a blue oilish tint to it, so it at least had some oil coming in the mixture. The top carb also seemed it couldve had a mild clog when i was blowing it all out.

My questions:

(1) There are 3 small tube hoses on the starboard side of the powerhead that meet in a 3 way T connector around the middle intake. Some of them come from inside the powerhead and i cant see how u would replace then. the ones on the replacement powerhead were damaged and im trying to use connectors on the same part off of another motor (same model) to extend and connect them back together. I see that the connectors have arrows on them so flow direction is important on them. I see that the one coing from the backside of the powerhead flows forward; does the one from the top flow downward into the T connector with the T connector continuing the downward flow into the bottom tube? Just want to be sure before I hook them all up and try to run the motor.

(2) The water hose that comes off of the powerhead down to the housing frame that the water pees out of; I think the old powerhead had it coming off the side of the exhaust plate with the port on the back above the spark plug plugged with a bolt; the replacement looks like it may have used that rear port, but there also may have been one on the exhaust plate port. Just to be sure, there should only be one hose like that anywhere around the powerhead right? Does it matter which port is used?

(3) The only other thing I have my doubts about is assembling the timing assembly but I may be able to find diagrams or something. Im sure I could also find the proper timing setting for this motor as well; but any tips to save me some clicks here would be appreciated.

 

[DavidMoore]

Not sure if this link is exactly right for your engine, but it should be pretty close.

http://boatinfo.no/lib/mercury/manuals/70-75-80-90-100-115.html#/110.

Question 1
I think you are talking about the enrichener hoses, look at page 110 in the link, should be self explanitory.

Question 2
Don't know, mine is an earlier model and has 1 hose, I would have to take look to see exactly where it exits the block but that's difficult now due to winter storage.

Question 3
The link gives the procedure for the timing, syncing the timing with the carbs, initial settings and the procedure for tuning the carbs.

 

[gydatree]

Thank you for your response. I havent had a chance to make anymore progress on the job yet but I do know after lookiing at the manual in the link you sent that the hoses im talking about are not the enricher hoses. They are smaller hoses up under the oil reservoir that lead straight into the powerhead with no connection on the exterior. The bottom one goes into the adapter thing on the very bottom where the splines connect.

Because they were damaged when I got it, I am peicing them back together using spares from another motor. I noticed that the connectors used have arrows pointing a certain direction, and I just want to make sure that I have them all going the right direction.

 

[gydatree]

UPDATE:

So I got her all cleaned up and put together. Fired right up with an obvious misfire in what sounded like the bottom cylinder, which is the one that was blown in the other powerhead. Replaced the voltage regulator and she fires on all three just fine. Water pumping through strong. Took her to the ramp, she pushed the trailer and truck just fine, so I pushed away out into the cove.

She shifts in and out of gear / neutral / reverse just fine. Once you start to accelerate it seems to vibrate the aluminum siding on the boat quite noticeably. With what seemed to be a slight hesitation, she gets up to about 3000 rpms super smooth and cruises just fine. Once you push the throttle more than that she hesitates, like a couple seconds, but eventually kicks up to 4500-5000 rpms and sounds great pushing the boat with great power, but loses rpms and goes back and forth from 3000-4500 rpms a few times before it stalls, and i gotta re-pump the bulb to re-start it, which it does get tight and hold pressure.

So, heres my areas of concern:

1) Carb idle screws- I think I have them out a little more than 1.5 turns.

2) Clogged line? I was thinking I would run a seafoam decarb and check the lines for any blockage. Carbs and pump were cleaned and re-built with new gaskets prior to running, but i didnt change the filter, seemed fairly new.

3) Fuel mixture? Im running a pre mix setup. Could it be to rich?

4) Those small hoses I was talking about earlier in the thread?

5) I have the timing setup idling at about 950 rpms. It could be turned up a tad to get it to 1000.

6) The prop is dinged up a bit around some of its edges.

Any suggestions would be greatly appreciated! By definition it seems its being starved for fuel somehow, but because i just rebuilt it and put everything back together im suspicious of everything haha

 

[gydatree]

Replaced fuel pump and filter, cleaned gas tank and lines, ran some quick clean through, runs like new.