Merc 80 still leaking?

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Re: Merc 80 still leaking?

Postby floater » Sat Dec 22, 2012 10:08 pm

P1030492.jpg
Here we go again!


Took the lower bearing cap off and found a fair amount of water inside and between seals but thankfully not any rust due to copious amounts of fogging oil after Ivy lake.

Have a good used bearing cap on the way from the colonies and new seals and gaskets already. will also be fitting speedi sleeves for a full belt and braces approach.

Hoping this will be an end to the matter.
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Re: Merc 80 still leaking?

Postby floater » Tue Mar 19, 2013 10:00 pm

Bought some Merc parts including a lower bearing cap off a guy on ebay that was selling due to conrod failure caused by oiler trouble:-

lwr  bearing carrier (spare).jpg
As delivered. This may have been the real cause?


Should look like this:-

correct.jpg


Not just me then.

Still not got the motor back on the boat. Did the seals just after Christmas but the weather has been so abysmal since I've not managed to get it all put back. No chance of being ready for Ivy Lake, pinning my hopes on Chertsey now.
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Re: Merc 80 still leaking?

Postby gfgarland » Mon Apr 15, 2013 3:16 am

If the problem persists you may have to pull the exhaust jacket off the side of the engine and inspect the exhaust jacket divider plate for cracks or corrosion, common in salt water use. The powerhead has to come off to get at all the bolts easily, but it is not a bad job, getting the cover off without breaking the bolts is! Go slow here and use lots of heat. Chances are the gasket or divider is at fault here and it is best to fix it pronto before real damage occurs. If the end cap seals are leaking as I suspect they are with the seals in backwards like that than the water will travel up through the bleed hoses and into the cylinders affected... so try it first. I would replace the lower bearing while you were in there as well.
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Re: Merc 80 still leaking?

Postby floater » Mon Apr 15, 2013 8:11 am

Thanks for your ideas. This motor has been a bit of a long running saga originaly started here:- viewtopic.php?f=7&t=3040 The original divider plate was quite crusty so was replaced early on along with the outer cover and inner baffle with new parts. I have been chasing this water ingress for quite some time and replaced many of the posibilities to the extent that the block is now a differnet one to that which I started with. The only constant has been the (incorect) fitment of the lower seals although I have fitted 3 sets during the quest. the lower bearing was replaced when I swapped blocks so only has a few hours on it and was saved from rust by copious amounts of fogging oil and WD40 after use. I have now installed a cleaner looking bearing carrier along with new seals (correctly fitted) and made up a stainless sleeve (same dims as a speedi sleeve but longer)for them to run on on the crankshaft.

I assembled the motor back onto the boat last weekend and have sent my entry to the Chertsey meeting in a couple of weeks. I plan to run it around constantly for at least a couple of hours and hope to see 4 dirty plugs at the end of it.

Thanks again for your advice, I have bent a lot of ears on this problem and am very grateful for all the help I have recieved :thumbsup:
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Re: Merc 80 still leaking?

Postby floater » Fri May 03, 2013 9:10 pm

Cracking day out at Chertsey today, ran the boat around for a non stop hour in the morning then a further hour later. got home and nervously removed the plugs. :woo: good news four beautifully grubby plugs. I think I can put this one to bed now. Twas the inverted seals all along :grrr:
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L-R cyl 1-4
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Re: Merc 80 still leaking?

Postby Alacrity » Sat May 04, 2013 7:29 am

Very pleased to hear that Floater, often the way that it turns out to be some simple. Looking forward to seeing her thrashing about at Hayling.
Mercs are like women, no 2 are exactly alike. That's what testing is about. In general it is safer to test motors and props than women!
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Re: Merc 80 still leaking?

Postby haventaclue » Sun May 05, 2013 6:24 pm

:perfect: :thumbsup: :drink:
no matter how bad it is,it can always get worse,I'm an optimist
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Re: Merc 80 still leaking?

Postby floater » Tue May 06, 2014 10:01 pm

So carrying on then.
I had real trouble starting the motor at Chertsey last Friday. The Motor was run in a tank at home about a month before and performed very well, starting easily with a bit of choke and idling smoothly all the way down to 800 rpm, so the reluctance at Chertsey was a bit of a surprise. When it finally started performance was poor with no idle so when it died it was again a real pig to start. This situation only worsened as the day went on. I even had the carbs off and checked for blockages.
I pulled the plugs when I got home and low and behold, water droplets again this time on plugs 2,3and 4. I pulled the power head off and have once again found a mess of cafe o lait in the exhaust chest and down the leg. I have once again pressure tested the assembled block and it holds 30psi well with just a tiny weep from the head cover around the plugs. The crank seals are good (and correctly installed)
So how about this for a theory:-
At rest the back of the boat and hence the motor sit low in the water, at idle the water in the leg pulses and some of it finds it's way upward into the exhaust. When at running speed everything is higher, pressure in the leg is higher and more constant keeping the water down. My constant efforts to start the motor on Friday exasperated the situation, low pulsing pressure in the leg with no high pressure exhaust to keep the water at bay.
Just a theory. :hmmm:

Alternatively the reeds in the bottom pot are shot resulting in vacuum in the exhaust tract sucking up water combined with difficult starting :o not a happy thought
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Re: Merc 80 still leaking?

Postby haventaclue » Tue May 06, 2014 10:27 pm

I think it may be easier than that,give the water cover bolts a quarter turn or so.Weeping water around the plugs is indicative of a bad gasket or loose bolts. Reeds are fairly bullet proof and seldom give bother.
Wouldn't do any harm to torque the crankcase bolts as well.
no matter how bad it is,it can always get worse,I'm an optimist
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Re: Merc 80 still leaking?

Postby floater » Tue May 06, 2014 10:41 pm

I think the weeping around the plugs is because I am giving it 30 psi, I have only ever seen 8 psi on the gauge when running so it never normally sees that much pressure. The top cover and mating top of block were both machined flat when I put the motor together. The area around the plugs is not well clamped as all the bolts are around the outer edge. So the weep is caused by pressure bowing the cover open. I am not worried by leaks on the outside of the motor my concern is leaks inside.
I agree that reeds are binary and either work or dont.
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boat at rest
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