89 Johnson no power at WOT

[ob]

No need for further water test tapping the primer at risk of melting down a cylinder. I'd make a plan to remove carburetors,one at a time ,and dismantle and thoroughly clean all fixed orifices and insure all passageways are clear and free of any restrictions. Best to obtain a rebuild kit for this process. The follow up would be to adjust the link and synch of each once complete and go from there. I use indexed torch tip cleaners for clearing of passageways as you can select one of close dimensional size and then soak and blow clear the residue.

 

[The Great Pre-Tender]

alright so i pulled off the carbs to do a rebuild and then remembered i had to do compression test.
the compression test revealed im guessing is some very bad news.

Cold engine
1st cylinder 96
2nd cylinder 0
3rd cylinder 95

ok, so where do i go from here?

 

[racerone]

Sounds like the typical # 2 cylinder problem.----Pull the cylinder head off now.---Another example of why I say ----" first thing to check is compression " on these posts.

 

[The Great Pre-Tender]

and take pictures or what am i looking for?

 

[racerone]

I think it will be obvious as to what the problem is.-----Hole in the piston.----Gouged cylinder wall.-----You have 2 cylinders to compare it to.----Then again it could be a blown head gasket.----But I doubt that.

 

[The Great Pre-Tender]

welp you hit that nail right on the head.

what causes this to happen and why is common to cylinder 2.

Is this something worth repairing?

Would it make sense to buy a powerhead and transfer everything from this motor to that? or is that unrealistic?
I can read and follow instructions and have a shop full of tools, but ive never rebuilt a motor before.

Either way, I really appreciate everyones help throughout this whole process.

Wish i would have started with Racerone's suggestion of immediately checking compression but i didnt.

 

[racerone]

Some will argue.----No surprise to me at all I say.----If you repair this yourself it can be done.-----But you need to understand the concept of determining what caused this or you will be doing it again !!----Finding a shop that will do this for you may not be easy.----Would be cheaper to find another motor !

 

[rdav13]

I Had the same issue with my 92 60hp.

There are several TSB'S for this engine running hot and scoring the #2 cylinder. Here is a link to my post of a summary of things I was advised at the time.

https://forums.iboats.com/forum/engi...issed-anything

Replacing the power head is not really difficult. No special tools other than a puller for the flywheel. You can research the price of the exchange reman power head, any repairs to the VRO pump if being used, carb kits TSB parts and get an idea if it is worth it to you.

I am in the process resealing the block halves now on the same motor. The reman power head developed a leak around the upper bearing. Here is a link to that thread.

https://forums.iboats.com/forum/eng...793-92-te60tlene-upper-bearing-o-ring-leaking

 

[ob]

Compressions good, I should have prefaced this by saying two weeks ago i took it out and it ran fine for the first hour then all the sudden it dropped off into the problem im currently having.

Sorry to hear of your findings.
This post is what steered me down the road of carburetor rebuild and trusted that you had confirmed good compression. While there is a TSB on these 3 cylinder engines on #2 having a tendency to run a bit hotter due to a lean condition..IMO your problem likely stemmed from restricted carburetors. Very common on any two stroke carbureted engine to develop gummy and restrictive deposits when not run regularly. And once they have restricted fuel it also starves the cylinders of vital lubrication. But hey .. stuff happens.

 

[The Great Pre-Tender]

Yeah sorry about steering yah down the wrong road AB but I do appreciate all the help even if it was for nothing.

 

[211libwtfo]

Lol uh yea please see post #2. Lol!! around here I can get a rebuilt power head cheaper than having a mechanic rebuild it..... parts prolly run about $400? That’s what I can get powerheads for. For most outboards.

 

[Faztbullet]

The main problem is the block as its a bridged exhaust. The failure is caused when ran at mid range the lean burn raises exhaust temps and bridge expands out. This in turn scuffs side of pistons causing rings to roll and break. Its a easy fix when rebuilding as I do it to all the ones like that I rebuild. The jetting just helps cool cylinder and bridge but bridge modification is the key.

 

[ob]

Hey Faztbullet, I'd be interested in the procedure for this bridged exhaust modification on a 1995 evinrude 70 that I run that doesn't need a rebuild but rather as a preventative measure. Assuming that this modification also pertains to my model year.

 

[The Great Pre-Tender]

Faztbullet i also saw someone people putting lubrication holes in the skirt of the piston, is this something you've had experience doing or is it unnecessary?

how much material do you take off of the bridge?
will it be the same on all cylinders?

Im going to buy a powerhead and do a rebuild. Stay tuned for that, Im sure there will be many more questions to follow.

 

[The Great Pre-Tender]

Also this may be a ridiculous question but since im rebuilding anyway.

What would it take to make this a 70hp? do they use most of the same components or is that a whole new set of complications?