Outboard Rebuild or Buy

[Abodedesign]

I know this probably has been asked a lot. I have a 1981 Johnson 70hp that I have been told has a bad Powerhead. I have gotten prices to rebuild motor with warintee from 1500 to 2000. New ones are much to expensive and I don't know what I am buying in a used one. Is it worth having it rebuilt.
Jim

[Landlubber]

I guess is that you know the engine better than anyone else, so you have to ask yourself this question, is it worth it.

If you have owned and cherished it for years, then you know that basically the engine is ok, just got a crook head, if you know that last year it sank in sea water and the bearings are most likely stuffed, then the answer is more obvious.

If you have just purchased it, cut ya losses, save for a new motor and then look after it

[Typhoon]

Only way to answer this question is to pull the powerhead down. If you have a lot of corrosion or badly worn bores, forget it. If it's fundamentally sound a rebuild is definitely viable, just don't skimp, have carbs and fuel pump(s) rebuilt at the same time.

Regards, Andrew.

[thudpucker]

I'd want to know why the power head needs rebuilding.
I've owned outboards of all sizes for most of my life and never rebuilt one!
I have had a bearing go out, and bought one that was overheated and seized.
But I never heard of a Two stroke that was worn out as long as the original owner had good Oil in the mix.

I'd want to look before I made a decision.

Corrosion eating the Carb and some of the Boss's on the block can make the whole thing a problem, buth when you consider the cost of replacment you'll look harder for a reason to fix it.

PS: I still need a starter for my 85 Hp. (1978)

[Landlubber]

thudpucker,

When talking about outboard engines, the "powerhead" refers to the whole engine actually, not the "head" of the engine as conventionally one would talk about. The powerhead is the motor section which attaches to the "leg", thus making a complete "motor".....yep, it is weird when you think about it, but that is the way it is.

[thudpucker]

Thanks, I did know that.
As I said, I've reparied them, but Re-building, ie; crank, rods, bearings, rings, seals, bore truing, surfacing, etc is something so rarely needed.
I'd want to know what the Mechanic saw that warnted Re-building.

[Typhoon]

Originally Posted by thudpucker

Thanks, I did know that.
As I said, I've reparied them, but Re-building, ie; crank, rods, bearings, rings, seals, bore truing, surfacing, etc is something so rarely needed.
I'd want to know what the Mechanic saw that warnted Re-building.

Dollar signs? $$$$$$$$$$$

Regards, Andrew.

[Frosty]

They really dont repair well--if you possibly can replace the power head at least.

If you don't, it is likely you will blow it again. A modern outboard is a high tuned motor kicking out lots of Hp from something you can carry around.

Old parts dont mix well with new,--you know the rest.

But if youve done it before then !!!!!

[thudpucker]

He never came back with the answers we need. He's likely forgotton he posted here.

[Typhoon]

I've never found outboards hard to rebuild reliably, in fact, due to less moving parts and roller/ball bearings, they are more succesfully rebuilt in my opinion. Both these type bearings in an outboard are typically carried in a shell and as long as teh running surfaces are clean and smooth, easy to guarantee reliability.
Same with bores, I've not seen a two stroke outboard that needed a rebore due to wear, they're just so soaked in oil by most users. Yes, pistons do seize but that's a fairly easy fix too.
As I said, as long as corrosion is negligible, there is no reason not to rebuild a powerhead if it is economical to buy the parts required.

Regards, Andrew.

[Frosty]

You dont normally pull them apart with nothing wrong with them.

Its usually because a ring has caught on the massive transfer ports. Typical 2 stroke failure.

Ive seen 1500in on some engines bearings that ran fine.

Ive replaced power heads without looking inside,--no need when a con rod is sticking out of the side,--that would'nt be repairable in my opinion.

I know the books say that if it measures up its good to go but in real life new parts just dont live on old surfaces. Its cost me a lot of time and money to learn that.

But your own time is much cheaper than someone else's time.

Why is it a bad powerhead anyway? whats wrong with it?

[Typhoon]

I don't understand what you are arguing about. I really don't. It's pretty obvious you don't repair something that's had a catastrophic failure.
I'll have to bow to what you consider to be your far superior knowledge on this subject as you appear to have seen it all.
Of course, I've never seen a 2 stroke powerhead that just needed a new set of rings to restore compression or needed new seals to get running right again, it clearly never happens.

Regards, Andrew.