Blown 70 Evinrude

[Daintreeboy]

Finally got the motor on my 16 foot Hartley looked at and as expected it needs a rebuild due to cracked piston. Cost is around $2200 so I'm not happy. Just when you get on top of the bills this s**t comes around.
It's a 97 model so I dunno whether to pay for the rebuild or trade it as is for a 60 Honda (how much are they these days?). Anyone got any spare lotto tickets they can 'lend' me lol :D
What do ya's reckon?

[peterbo3]

Hi DB,
It always happens at the worst time. :'( :'( :'( I had the 60 hp Johnno, same motor but with different carby set-up. Fortunately, never any problems. The 3 cyl motors are normally very reliable. What caused the cracked piston? If everything else is OK once it is torn down, I would tend towards the rebuild providing there is warranty or possibly look at a second hand power head
from an O/B wreckers. There should be plenty around as this was a popular engine.

[NQCairns]

Hi there Daintree, Why so much?? How many hours on the motor? I didn't know it was so young.
Depending - the bearings should be ok. Was this quote for a full everything back to brand new rebuild?
A rebore and new oversized piston kit on cyl 1 then a hone on all cyls and rings and gaskets, my uneducated price guess would be 6-800 dollars for parts and machining add $500 for labour and you are back on the water, what's the extra for? #I say keep the motor you should get 10 very hard years minimum out of an engine, such a bummer on so young an outboard. just thinking wont the 60 Honda have the performance of a 55 2stroke. Could you get away with that where you fish, fuel economy would be grand though.nq

[Daintreeboy]

I haven't actually seen the quote yet to get all the details so I'll get back to you on that one.
For the type of boat and fishing we do, a 60 or 70 4 stroke would be good. Just gotta get some quotes.

[Cloud_9]

i think the rebuild will be a lot better on you wallet.
but you should try to sauce a second hand powerhead.
where are you in the state?? if your in brisbane i know someone how may be able to help!!

[Kerry]

Really it's not as if it's an old motor or anything: So the question is, what cracked the piston ???

They generally don't do that for no reason.

Cheers, Kerry.

[Lucky_Phill]

When I read the heading to the post, I thought you put a Supercharger on your OB ! ::) :o ;)

The question still is....why did it crack ?

Heat is the obvious answer. fuel / oil ratio ?

Phill 8)

[Daintreeboy]

My brother went fishing in it one day with a mate and they'd only gone a few miles before it just stopped. The fuel bulb was full of water. The local servo was the culprit. He emptied it out and reprimed it and it went. He kept an eye on it that day and it filled up another 2 and a half times (he kept emptying it before any more got in the motor).
Anyway, we suspect this could have had something to do with it as the motor looks in pristine condition just looking at it.

[Kerry]

Water isn't going to blow a piston ??? and if one realised just how much water most outboards actually injest then there's more to this than simply a fuel tank full of water.

Cheers, Kerry.

[NQCairns]

Hi agin Daintree, I too wonder like Kerry how injesting water through and with the fuel would crack a piston on a carbie engine, way above my diagnosis abilities that one although it looks like new bearings are now on the list of rebuild parts, makes your quote more solid, what a shame :(. Good luck nq

[Daintreeboy]

Fair point but we suspect there was more in the fuel than just water. I know there is a filter after the bulb but there is suspicion something may have gotten past it somehow into the engine. Kinda doesn't make sense the way I've written this I know but I'll be chatting to the guys when I go in to pay for the other motor's servicing bill and get a better idea.
I'll keep you posted.

[Kerry]

This "filter" after the bulb: is that referring to the standard under cowl filter or a "proper" fuel/water separator.

If this motor was relying on the under cowl filter then if what they say is even part correct, a few $$'s for a good filter might have saved all this trauma.

Another question: motor is oil injected or premix ???


Cheers, Kerry.

[Daintreeboy]

The motor is premix and we're pretty certain no stuff up has occurred there. The filter is indeed the under cowl one past the water trap.

[Kerry]

The motor is premix and we're pretty certain no stuff up has occurred there. The filter is indeed the under cowl one past the water trap.


"pretty certain"? does that mean the fuel was oiled correct or just being hopefull.

"water trap" as in just an after market accessory water separator, no included filter?

Cheers, Kerry.