Might explain why its not working!!!

[lockieboi]

Any ideas how this could of happened?

[xs 400]

hi there!

if thats a piston, if those are scores in the piston, has the piston ring broken up and caused it??

oil starvation?

whats the bore like ?


hope you get it sorted.....hope to catch up with you again this year, lulworth the return

[jwalker]

Major overheat - presuming it's a 2-stroke, no oil in fuel, no water circulation within the engine.

[Nos4r2]

Originally Posted by jwalker

Major overheat - presuming it's a 2-stroke, no oil in fuel, no water circulation within the engine.

Yep.If only one piston, maybe an air leak or blown crank seal too.

You need to find the problem before you go repairing the damage.

[lockieboi]

Thanks guys.
The piston rings have been replaced and its now running but obviously I want to find out why it's happened before i run it to much.

The bores are a bit scored also.

It's always been run with oil in the fuel 50:1 whilst I've owned it obviously I can't speak for the previous owner.

[Nos4r2]

That piston is FUBAR. Don't run it again .You need a rebore as well.

If you carry on running it, it'll seize and it may trash the bore so badly you'll have to either scrap it or put new liners in.

[lockieboi]

Originally Posted by Nos4r2

That piston is FUBAR. Don't run it again .You need a rebore as well.

If you carry on running it, it'll seize and it may trash the bore so badly you'll have to either scrap it or put new liners in.

Thought as much.

The pictures are of both pistons, the first picture is of the top and the other 2 are of the bottom. Not sure if this helps with diagnosis.

[Nos4r2]

Yep, it's totally fubar. Probably overheat damage at a guess then.

It needs a rebore on both cylinders and new oversize pistons. Probably needs new bearings as well-those bits of metal that are missing all go somewhere...

[lockieboi]

Thanks for the help.

Any ideas how it could of overheated? Maybe a faulty thermostat?
It's always had a steady flow of cooling water.

[Nos4r2]

No idea- wrong oil, carrier bag round the prop, furred up waterways? Could be a faulty stat if it's a model thats got one.

I'd price the repair up before you commit to anything-it may be cheaper to flog it as spares and buy another motor.

[lockieboi]

Originally Posted by Nos4r2

I'd price the repair up before you commit to anything-it may be cheaper to flog it as spares and buy another motor.

Good thinking

Anyone know anywhere that rebores?

[Nos4r2]

Check out if it's a chromed or nikasiled bore as well. If it is, it'll need redoing.

[9D280]

If it's a 2- stroke you might have a too advanced spark as well....... (Don't ask how I know that destroys pistons! )

That looks prety bad. I would guess you are looking at replacement pistons there, unless that is a trick of the light. Unless you can get away with a couple of thou' skim you are probably looking at at least a 0.015" - probably 0.30" bore & replacement pistons. Replacing just the rings at anything above about a couple of tho' will result in a rattly piston and a apid route to it's next self destruction. Looking at those photos I'm not thininking "polish" will work in those bores. Any pics of the Cyls?


I found the same thing as the result of a too advanced spark. The one good thing about this kind of disaster is that when you rebuild it you have a known engine of zero running hours, and you know all gaskets are new, all seals etc have been replaced......


Google "Mallory" & "Sierra" - they do replacement pistons for pretty much any outboard. Mine now carries Mallory.

[nugent]

Originally Posted by lockieboi

Good thinking

Anyone know anywhere that rebores?

Coventry boring well experienced in out bored machine work

[paddlers]

Identical to my 115 mariner that went into Pennine Marine as a runner until the afternoon they messed about with the timing !! Still trying to work out if they didn't premix the fuel or advanced the spark to destruction. On the Monday it had decent compression on Thursday it was a £470 bill & a box of bits ( that live in one of my sheds).
One of the pistons also clipped a port........
Good luck with the rebuild, when I looked at the cost it seemed prohibitive ?

[9D280]

Originally Posted by paddlers

One of the pistons also clipped a port........

Exhaust port? If so sounds like a way to advanced spark to me...

Originally Posted by paddlers

Good luck with the rebuild, when I looked at the cost it seemed prohibitive ?

I guess it depends on the borer / where you buy the bits. I reckon it cost me just shy of £800 to rebuild mine, (not including the PT upgrade) by the tme I had bought a full set of pistons, rebored the head (Blind bore on the clamshell so a little more expensive) and replaced all the gaskets / oil seals etc.

My reckoning went thus: I spend £800 rebuilding an enngine that's worth about £700. For that money I could go& buy a "runner" only to find it goes terminal very quickly, and have to spend another £700 odd....... By rebuilding I know it's full history - or at least the bit of it that counts when it comes to getting back.


If you look at it purely as insurance values, you'd never rebuild an aeging outboard.

[nugent]

Originally Posted by nugent

Coventry boring well experienced in out bored machine work

Best source for cheap paterned parts

http://www.tmp-murcury-mariner.co.uk...ine.html#rings


Personally prefer genuine in my own builds but some times needs must

[paddlers]

I wouldn't rule out me rebuilding this one if I ever get around to rebuiding the Honda quad & Honda trike in my sheds oh & my BMW R80RT oh & my two ride on mowers etc etc.
Cheaper & quicker for me to buy a complete engine from Clyde Outboards on here delivered & fit it to the transom.
I'll probably in the market for a decent Yamaha in a couple of years to see me out..........