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Old 21 February 2019, 07:39   #11
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Do you remember what colour the oil was going in?. How many hours has it been in? Nik
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Old 25 February 2019, 06:29   #12
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Thanks for all your comments.

So had a try with pressurising and the input shaft and prop shaft blew easily but there was no obvious signs of failure, shifter shaft held fine.

Have opened up the gearbox and washed out the emulsified oil and the trapped water (was sitting somewhere out of reach of the drain??). Inspecting the contents there's no sign of corrosion or damage. - pictures attached. Main shafts don't appear to have deep grooves where the seals run.

I am going to order new seals allround and water pump gaskets. Only dodgy looking bit is the water pump lower casing, but may clean up ok.

Anything else worth checking at this stage?
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Old 25 February 2019, 08:01   #13
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Renew 'o' ring on dog clutch gear rod. Also 'o' ring under water pump above drive shaft bearing.
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Old 25 February 2019, 14:36   #14
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What is the history to the gearbox? How many hours on it? Were you the last person to service it?


Personally id have changed the prop shaft seal and put new washers on the fill/vent plugs and run it to see if water appeared again before tearing the whole gearbox apart.


I'm of the belief 'if it aint broke don't fix it'
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Old 25 February 2019, 15:12   #15
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Hi Swifty, you've done a great job. I'm watching this with interest as we have a dribble of water in the oil in ours. Did you have diffs removing the output carrier or generally dismantling it due to corrosion etc??
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Old 25 February 2019, 16:15   #16
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That water pump lower housing looks like Swiss cheese. If the surface has deteriorated to such an extent, it would be worth replacing. No point buying new waterpump gaskets if they're not seated properly. There's Yamaha parts diagrams on Boats.net. Easy to navigate with engine year. Think part is around 90 plus shipping.

While you're there check the sacrificial anodes on the engine to see they are doing their job, including the earth cables on the leg.

I've started using Salt Away at the end of the season. Granted it wouldn't stop water ingress on a failed seal, but think of the cooling passages, water jacket, thermostat.
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Old 26 February 2019, 09:11   #17
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To answer your questions...

I have indeed ordered a new water pump housing at 81 along with all O rings and seals. Total is about 150 for parts.

The ring nut was a bugger to remove. I started by drifting it off but it started to flatten, it's made of alloy, so made a jig out of sheet steel and a couple of M8 bolts. Two of us using long prybars between the jig and the propshaft shifted it.
Hub carrier came out easily with a puller but I did have to make some extension arms for the puller to reach from the end of the prop shaft.

The engine is circa 1998 and total hours are unknown, but probably a couple of thousand. It's done 350 hours since the power head rebuild a few years ago. Gearbox was overhauled two years ago by Yam dealer as the gearshift was getting clonky. They had to drill the ring nut to remove it. I was very relieved when they reported all internals were in good condition.

I usually change engine & gear oil every year, spark plugs & impeller every three years. I didn't change oil last year due to the rebuild and low hours. With hindsight, I should have done it anyway and not trusted the dealer. We live and learn.
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Old 26 February 2019, 10:29   #18
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swifty any idea why the oil is black very interested because i've seen it before in a johnson 15 hp it smelt like exhaust fumes but wasn't sure it had the correct oil but this had no water ingress.

cheers jeff
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Old 26 February 2019, 11:20   #19
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Quote:
Originally Posted by jeffstevens763@g View Post
swifty any idea why the oil is black...

cheers jeff
Nope, it didn't really smell of EP90 either! It had the consistancy of epoxy glue and the total volume of what came out was less than half the normal capacity. Maybe oil was being forced out when running hot and water sucked in as it cooled down.

I think I was lucky to uncover the problem before complete destruction.
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Old 26 February 2019, 11:59   #20
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Quote:
Originally Posted by Swifty View Post
Nope, it didn't really smell of EP90 either! It had the consistancy of epoxy glue and the total volume of what came out was less than half the normal capacity. Maybe oil was being forced out when running hot and water sucked in as it cooled down.

I think I was lucky to uncover the problem before complete destruction.
I remember in the old days when the cylinder head gasket went on the car you had a creamy residue in the rocker box but that was cream to white in colour
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