My first 3.0 EFI

[Aaronhl]

This thread will be for the questions I have about my first 3.0L Merc EFI Outboard. I neglected service of the engine once I got it earlier this year only to instead run it hard a few times and burn down some cylinders...There's atleast one person that warned me to do some maintenance :)


I have the winter to learn as much as I can to fix the engine, been kinda intimidated by the EFI setup as my other Mercs are 2.5 carbs...


Powerhead
0G325775
1996 Outboard 225EFI


On a 20" Midsection
1B321430
2006 250 PROXS


Heres a pic of the engine and will posts questions as I have them

https://i.imgur.com/TjCWSfb.jpg

[Aaronhl]

Heres what happened a few weeks ago to #2 and #4, I have since took out the 2 bad pistons and removed the aluminum from the cylinders walls with acid, I am awaiting a 120 grit ball hone :D

The "rebuild" right now is hinging on a good compression test after I hone the two bad cylinders and put some pistons back in there. Looking at the scratches I know its not ideal but I kinda want to try to do this way first before I get the cyilders professionally done...

https://i.imgur.com/pJ1qPQJ.jpg

https://i.imgur.com/TpLqYSz.jpg

https://i.imgur.com/1NyV8yM.jpg

[Aaronhl]

First few questions


Where is the port side temp sensor?

Should I plug the wash out port so water doesnt constantly come out while running? Is that making it so my engine doesnt keep water in there to cool?

Which powerhead gasket do I use with this mid section?


Will be going through eveyrthing including injectors, replacing reeds, and testing the electronics

[rgsauger]

Also ask the fellows that know if you need to have the rubber flow diverters installed in your block before you put the heads back on. I know you do for a 2.4 and a 2.5 but I do not know about a 3.0

[Code Red]

Following. I'm trying to get my first set of 300 promaxes up and running (bought 1 blown), so I also have plenty of questions.

As for the diverters, I know I have them in my motors. Ill post some pics when the block gets back from the machine shop.

[Aaronhl]

First time I am hearing of diverters, I searched to see they are tubes to limit the flow of water around the cylinders... I havent seen them in my 2.5 and this 3.0 doesnt have them either
I'm concerned about making sure this 2006 250PROXS exhaust plate fits the right way on the 1996 powerhead. AND cools the engine like it should The person that put it on previously used a paper gasket with a bunch of silicone

[moparbarn]

Aaron, I would not use a ball hone on a ported cylinder- EVER!! They are notorious for losing & chipping balls on port edges. Little chunks of abrasive material can & will destroy an engine in short order. Easy to miss & difficult to clean out of the block. Old school straight stone hone on a ported cylinder, IMHO. I would have to think the flush plug needs to be in place for the cooling system to work properly.

[PanRonnie]

I added the later style and early style 3 cooling sadly the book of the older engine has no cooling route page
but the older would be similar as the 2.5 with the exception it wouuld only have holes next to the bottom cylinders
Now would it be necessary to add diverters !? i added some possible locations for partial blockage but don,t think it is necessary
so your cooling would come in next to cylinder number 6 towards the exhaust then flow around both cylinder walls upwards to the top then drop down over the heads and exit through the bottom hole entering the mid plate

The newer engine would have the same place entering the around the cylinder walls but stay on one side going up to the to and around to the bottom
At the bottom it would divert to the mid plate towards the poppet valve and second route in the cylinder head entering from the bottom going to the top where it reaches the thermostat
the thermostats probably have a bleed hole to bleed the air and start to open once the thermostat reaches desired temperature

[Aaronhl]

Aaron, I would not use a ball hone on a ported cylinder- EVER!! They are notorious for losing & chipping balls on port edges. Little chunks of abrasive material can & will destroy an engine in short order. Easy to miss & difficult to clean out of the block. Old school straight stone hone on a ported cylinder, IMHO. I would have to think the flush plug needs to be in place for the cooling system to work properly.

I was gonna buy the 3 piece stone hone however I saw in older threads the ball hone is better so you dont chip a stone??

[moparbarn]

You can chip a stone, if you catch a port edge with the end of the stone. Key is to buy one with long enough stones to bridge the ports at both ends of the travel. Ball hones are entering the ports & then getting dragged out across the edge of the port constantly. As long as the END of the stone hone doesn't enter the port, it is fairly rare to chip one. Also MUCH easier to check a stone for chipping than all those individual balls.....

[Aaronhl]

Got the ball "dingleberry" hone in the mail today, used it on the two bad cylinders, here are the results, gonna order some used ebay pistons, a cylinder head, new piston rings and o-rings well see what the compression looks like after that

https://i.imgur.com/P3gkXxF.jpg

https://i.imgur.com/EAEVI9W.jpg

https://i.imgur.com/CX5haMz.jpg

[Chaz]

No port side head temp sender .. only starboard.

If you mean where a garden hose will screw into the rear snorkel , then yes it needs to have a plug screwed in.

They have superseded the base gasket's so many times, that they have settled on two. Either will work, the standard $26 dollar one and the $55 dollar hi-perf one (pro marine)
The only place it makes a difference is the gasket between the exhaust adapter plate and the can. Early model is green and the late model (like yours) is standard greyish black.

The early-early blocks didn't have water diverters. They added them later , you would be able to see half round places where a 5/16" x roughly 2" piece of solid rubber round stock would fit in.

It looks like you left the hone in one place and just let it go in circles. There needs to be a cross hatch that has a 30 to 45 degree pattern to it.
Some of those deeper scratch's / gouges looks like they have a raised burr on each side of the trench. If nothing else, hand sand the high spots down.
The low spots .. I call "oil retention ponds" :)
Even if it looks like a brand new penny, you need to measure each bore to make sure its still round. Top- bottom on the thrust face and top-bottom at 90*. 3.626-3.627 after that, it's wise to bore the block.
A real hone can apply pressure to the walls to straighten them out. Those springy thingy hones .. not so much. Ball hone, not at all.
Used, std. 3.0L pistons .. if they don't measure at least 3.617 on the thrust face just above the boost port window ... I won't use them.

What Moparbarn spoke about it somewhat true. An interrupted (ported) sleeve or "Keystone" as it's called thru-out the industry , says that the best way to hone sleeves with holes in them is with holders with two stones per holder across from each other and two guides arranged in the same fashion.
My powerhone uses AN style stones. The standard Sunnen AN stones work just fine. And there are times where the short "bottom pressure" stones are needed to straighten out a hole. I have never had a problem with one catching in a port.

After you wash the block 3 times and it's all ready to go ... wash it again .. :thumbsup:

https://goodson.com/collections/sunnen-honing-stones/products/sunnen-my33-j65-keyway-honing-stones

[FUJIMO]

...r u doing this with an assembled motor?...

[PanRonnie]

Still see a lot of grooves!
Might be an idea to just send the block to somebody to get it fixed
bristol Season is also over

[Chaz]

...r u doing this with an assembled motor?...

Now that you mention it ... I do see a crankshaft in there.

PanRonnie

Might be an idea to just send the block to somebody to get it fixed

Aaron, both these guys are right. The motor needs to come completely apart. Washed, measured with a dial bore gauge and then make some decisions on which direction to go.

[rgsauger]

Hey bud, you gotta listen up on this one or just get ready to throw the whole junk in the trash. If you honed this motor while the rest of it was still together, I’m sorry but you’ve got to take it apart and clean it out. There’s absolutely no way that grit and debris did not get into your motor. If you care about it at all, it’s gotta come apart and get cleaned. Sorry but that’s the truth. Unless you know something that we don’t… like you had the world‘s best shop vac hooked up to it and you put clean oily rags in the bottom of the bores and that type of thing. Even then, the guys that do it for a living would still insist on it coming apart.

[moparbarn]

Gotta.STRONGLY agree, just a ticking time bomb at this point!! Might as well have mixed valve lapping compound in your fuel.....:eek:

[Chaz]

Late model blocks had a row down the middle. The bottom one is offset to send water around the outside.

https://i.imgur.com/ViYDGxTl.jpg

The later early model blocks had a couple-few offset at the (aprox) seven O-clock position. (yes those are late model sleeves in an early block, no ex-notch)

https://i.imgur.com/JXxsJHPl.jpg

https://i.imgur.com/NRFSjgHl.png

Taxi-cab Mirage .... Behind the liner porting, late model sleeves, 3.1L, 300 ign / 250 fuel boxes, late model plenum, 300x reed adapter plate ... bury a 120 mph GPS speedo with a 35" Hoss wheel .. still plenty of life left in them ole gals ... :thumbsup:


https://www.youtube.com/watch?v=VYMNq2IKMKc

[Aaronhl]

oh cmon guys u tell me this now

[FUJIMO]

...why? is it too late?...

[Aaronhl]

well i guess :),,, i did hone the engine with it upright if that helps any,

there was bad gas and water in the gas tank when i bought the boat and looking at the condition of the crank weights and edges of the crank journals it was ran (sat with water in it) so there is rust on those parts and ideally it should be torn all the way down

I feel i can clean it pretty well but the rust is not something that will go away and im sure it can irritate just like the honing dust that is leftover

[FUJIMO]

...a DDA (detroit diesel allison) engine, while in service out in the field or in the bilge, are done this way. not a two stroke. a two stroke is of the highest "sustained" r.p.m. range engines, out of the three main engine design groups. (diesel being the lowest rpm). a two stroke rebuild should be performed in a "clean room" envirement & always completely gone through. rust of any kind internally in a two-stroke, translates into a very short lifespan. very short. just as an example.

[Chaz]

oh cmon guys u tell me this now

Aaron, be grateful that Massa Fugiphotosan caught the fact that the motor "was still together" and said sumptin .. :cheers:
Even if you didn't try to hone it, some of that slag from the burnt pistons has went back into the lower crankcase and into the bearings along with every nook and cranny.
If you find some grit in the intake manifold, then chances are pretty good that it got drawn into other cylinders as well.
As it been said .. many times .. pull it apart ... completely !
Wash everything ... then picture and question time .. :)
You might get a few .. pokes or prods along the way .. :D
But I assure ya .. ain't no one gonna leave ya hangin halfway thru the build .. or steer ya in the wrong direction ... :thumbsup:

[Aaronhl]

yea i hear ya you guys are always helpful and im gonna think a little bit about what I want to do over the winter with the engine

Do you think I got all the piston ring pieces out??????????:D

[moparbarn]

Only 1 way to know, tear it down & see. All roads are leading to a complete teardown.

[Aaronhl]

Do you guys concur this is detonation of the piston caused by those cylinders being lean? Either not enough gas through the injector or two much air through a reed?? Is there some sensor or electronic that would cause this issue?

[Chaz]

Let us know the before and after flow numbers of your injectors. Then we'll see the answer together ... :cheers: