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Old 04 October 2012, 15:38   #11
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Originally Posted by paddlers
Frustratingly this engine ran beatifully for two weeks before going in & even the mechanic stated that all the issues (float needles replaced). At @1.30pm rang me to ask if I had the timing cover for the flywheel but I hadn't, he said they'd manage. By 4.30 pm my engine was scrap.
I?
Just wondering about the missing timing cover for the flywheel .
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Old 04 October 2012, 16:47   #12
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They're available from the USA & I would've bought one had I known it was missing. It has the marks to time the engine on it but the bloke said that they'd rig something and they be fine. Now of course they have concerns about the engines condition but it ran fine for two weeks of waterskiing etc and on the day they rang to enquire about the cover no issues. The next day when it was damaged old engine etc my problem. On one post on ribnet there's mention of setting the spark too advanced causes the petrol to ignite on one side of the piston dam pushing the piston into the exhaust port almost exactly as described to me by the mechanic on the phone but it's how to prove it ?
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Old 04 October 2012, 18:17   #13
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There are two approaches:-

1) Collect evidence that incorrect timing adjustment can cause the damage, confront him with it and ask him to fix the damage at his cost. If he does not accept it then go down the legal route - unless you are insured your leagal costs could quickly outweigh the cost fo a replacement engine with no guarantee of success. I dont think either way is sensible.

2) I think I would suggest that you try to work with the guy in the first instance by showing him the post that cites timing adjustment as cause of piston damage and any other more reputable sources - maybe a authorised Mariner dealer? I don't think you will ever be fully compensated for the damage but if you work with him you might be able to mitigate some of the costs - if for example he accepts any blame he may not charge for any corrective labour required and maybe help in sourcing a secondhand powerhead, rebore etc. This assumes you would trust him near another engine.

Just my tuppence worth...
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Old 04 October 2012, 18:38   #14
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Quote:
Originally Posted by TomKat View Post
There are two approaches:-

1) Collect evidence that incorrect timing adjustment can cause the damage, confront him with it and ask him to fix the damage at his cost. If he does not accept it then go down the legal route - unless you are insured your leagal costs could quickly outweigh the cost fo a replacement engine with no guarantee of success. I dont think either way is sensible.

2) I think I would suggest that you try to work with the guy in the first instance by showing him the post that cites timing adjustment as cause of piston damage and any other more reputable sources - maybe a authorised Mariner dealer? I don't think you will ever be fully compensated for the damage but if you work with him you might be able to mitigate some of the costs - if for example he accepts any blame he may not charge for any corrective labour required and maybe help in sourcing a secondhand powerhead, rebore etc. This assumes you would trust him near another engine.

Just my tuppence worth...
I agree with TomKat, I believe this would be your best approach.
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Old 04 October 2012, 19:03   #15
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id try and work with the guy its a 20 year old engine proving what went wrong is going to de difficult

true incorrect timing can damage pistons but incorrect fuel
mixture can do exactly the same thing (melt pistons) and it went in for a fuel fault!

I ran a garage for 25 years and occasionaly things go wrong if the guy is an honest trader then he will feel guilty about the engine going wrong while in his custody but its human nature to look after yourself and deny liability give him the chance to quote for repairs & hopefully he will try and rectify the situation by offering to complete the repairs as a reduced rate

if you get a favourable response then go with it if hes negative and asks the earth for repairs then get it back & start looking for a sh engine

in my opinion its not worth the stress and expense of involving solicitors
but thats only my opinion of course

whatever happens good luck
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Old 04 October 2012, 23:25   #16
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I agree that it's very difficult to prove & my initial feeling from the first phone call after the phone call to say there was a problem when I asked " is it anything to do with altering the timing " was " it's nothing we've done!".
The fuel was occassionally leaking from carb 3 for the whole of our two weeks holiday & never caused a running issue at all. New tank & fuel line plus I mixed all the fuel myself( Yamalube) at 50:1 fresh fuel in August. Used @ 140 litres with no problems, no unusual noises/smoking etc & pulled like a train!
Of course the firm are not admitting anything but having taken advice from C.A.B & trading standards that's to be expected !! It costs 70 online to put it into court and you'd think commonsense would dictate some flexibility on their part but I suppose money rules!
I was hoping that someone could put me onto somewhere that proves the link between spark advance & piston damage that would support the fact that it's possible to damage the engine?
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Old 05 October 2012, 03:36   #17
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Quote:
Originally Posted by paddlers View Post
I agree that it's very difficult to prove & my initial feeling from the first phone call after the phone call to say there was a problem when I asked " is it anything to do with altering the timing " was " it's nothing we've done!".
The fuel was occassionally leaking from carb 3 for the whole of our two weeks holiday & never caused a running issue at all. New tank & fuel line plus I mixed all the fuel myself( Yamalube) at 50:1 fresh fuel in August. Used @ 140 litres with no problems, no unusual noises/smoking etc & pulled like a train!
Of course the firm are not admitting anything but having taken advice from C.A.B & trading standards that's to be expected !! It costs 70 online to put it into court and you'd think commonsense would dictate some flexibility on their part but I suppose money rules!
I was hoping that someone could put me onto somewhere that proves the link between spark advance & piston damage that would support the fact that it's possible to damage the engine?
I know it's not what you want to hear, but IMHO you're on a hiding to nowhere by going to court. The dealer will say that you took the engine in for a service & to attend to a fault on the carb, during the course of the service they found damage to a cylinder & reported this to you.
The engine might have been running with a dodgy cylinder for a while.
You could ask them to put the engine back together again & see if it runs.
You could ask for the engine back & get a second opinion on it's condition.
You could have the dodgy cylinder re-lined (if this is possible on this particular engine , I dunno) & a new piston fitted.
You could bite the bullet & get a replacement engine, which in all honesty will probably cost as much as all the above if you replace it with one of similar vintage.
You could jump up & down, stamp your feet & see if you get lucky with the dealer, but start off nicely
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Old 05 October 2012, 04:43   #18
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Tech bit in plain english:

It's a 2- stroke. There are no valves, as the piston doubles as the valve. To ensure the incoming "blast" of air / fuel mix both fills the void & "blows" the exahust out the exhaust port, the piston has a "dam" across the top:

http://www.sterndrive.info/sitebuild...rd-pistons.jpg (random example from Google)

if the timing is advanced too much, the spark happens before the full "flush" has happened, resulting in more air / fuel one side of the dam than the other (the other side is still essentially non combustible exhaust).

Because the piston is it's own valve, if the spark happens too soon, at the "bang" moment the piston is still below the inlet / outlet ports, and so when the spark goes, the mix ignites onthe inlet side of the dam and creates a bigger "bang" on the inlet side than the outlet - net result the piston is pushed hard into the exhaust side of the cylinder, while still rising to compress the mix.

This results in a collision between the top corner of the piston and the spark plug edge of the exhaust port. The resulting debris gets wedged in the rings & makes a nasty mess.

Not that I know from experience or anything......


So, Replacement piston (Mallory / Sierra) - 75-100 or shedloads for an OEM one.
Replacement rings (for the other cyls) about 10- 15 for a set (maybe a little more if it's a V (more cyls than my Clamshell)
Rebore - I was quoted 120 for three cyls. Probably a little less if yours has a "proper" cyl head - mine is a blind bore design, which did complicate matters slightly.

The biggest PITA s dismantling it for the rebore. On the plus side, you don't need to do all the bores.



FWIW when mine destroyed itself (Locknut on the spark advance let go, so the adjuster screw wound itself out and the first I knew of it was when I opened the throttle and it stopped dead as the plugs were shorted by the metal that was chipped off the corner of the cyls!) I priced up a full rebuild. As Pikey says, it came to aboiut the same as a replacement engine (of unknown history). I decided to rebuild so I at least knew it was done properly. During the rebuild I fitted al lthe latest level parts, so dragging my engine form a 1970s build to a last production, which on paper at least should prevent it form suffering form all the Clamshell problems they were reknown for in the early days.
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Old 05 October 2012, 05:09   #19
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Thanks for that, just the sort of detailed post I was looking for. The point of my origional post is to understand how adjustment of the timing which by their own admission they did could result in the destruction of a bore which they stated " a piston clipped one of the ports"!
This engine ran well right up to this particular afternoon. It's also a blind bore but the prices you've mentioned don't seem unreasonable when you consider the cost of an equivalent outboard. The problem really is the dealer who comlpetely refuses to admit they've possibly made an error & rectify the problem! It's a bit of a worry given the prices charged & the instant that there's an issue "sorry mate"!
I intend to write to them next giving them an opportunity to reply & repair the damage but given that I've spoken to them on the phone I'm not optimistic.
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Old 05 October 2012, 07:36   #20
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It is unlikely that the timing would cause this unless you were running under load for a long period. The main cause of bore damage is very often due to overheating, in these cases and if you could get a look at the pistons you would find the rings compressed into the ring groves with the piston material often dragged over the rings. The question I would ask is - was an water supply or tank used during the testing or running of the engine?
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