Merc 80 still leaking?

[floater]

Put the boat with its 1979 Mercury 80 into hibernation for the winter on Friday following a cracking day out at Ivy lake the Sunday before. The boat and engine live outdoors under a tarpaulin so amongst other things I removed the gearbox and pushed some fogging oil through the carbs. Before doing this I removed the plugs and was very dissapointed to see tiny water droplets on plugs 2 and 3 and that plug 4 was very clean (no soot or oil) By tiny droplets I mean I needed a magnifying glass to be sure, plug 1 (top) was dry and carbonised.

As some of you will know from my "Merc 80 she lives" post / essay I have replaced many of the parts that could be considered culprits for water ingress, baffle plates crank seals and even pressure tested the assembled block.

So my question is this (at last you sigh):-

A) Are the droplets on the plugs condensation from a warm motor left to cool over a damp and occasionaly frosty week, plug 4 a mystery of cleanliness.

Or

B) Is the motor still somehow taking in water despite seeming to run perfectly. If this is the case suggestions of where to look gratefuly recieved.

[sean-nós]

Could there be water in the fuel also Doing a compression test should tell you if a cylinder has been breached.

[rnb]

I thought water was a by product of the combustion process , witness water flowing from your car exhaust often quite liberally . I know we are discussing a two stroke but water is also present during the combustion cycle , you did state its only small traces .. are you being a touch paranoid , i dont know ?

I guess i would be worried/paranoid by a completely clean plug with no deposits though .

[floater]

The fuel tank is portable plastic one and both tanks were filled with ESSO supreme 97 four days before. I have got but not yet fitted a Mercury water seperator / fuel filter although there is a small in line filter fitted just before the pump.

Good idea to check the compression I was thinking the same myself having scoured the internet in search of ideas. I did a compression check when I rebuilt the motor last year, I cant remember the readings now but know that they were good. I did write them down so will be able to see if something has changed significantly.

[haventaclue]

I find the plastic tank very prone to condensation and we've had a couple of pretty warm days,for the time of year, followed by cold nights. Would suggest you put the small inline filter after the pump,hard on the pump to suck the fuel through the filter,it will pump easier than pull.
Compression for these should be 110+,and as you have rebuilt,I think 130+ would be a good figure.Unless you're using an old compression tester of unknown origin,like mine
On the clean plug,can you put it in a tank,fire her up for a couple of seconds,check see if there is fuel on the plug.What does the top of the piston look like? Earth the plug,turn her over and see what she spits out the plug hole

[floater]

I confess to being completely paranoid about this motor, it did nothing to give me any confidence in it when I kept having to pull it apart sorting out leaks before I fitted it to the boat. To be honest I have gone in search of trouble to a degree so anything out of the ordinary makes me nervous.

The plastic tanks were full and I drained them driving the boat around the lake constantly rather than stop start. My plan was to get some time on the motor to run in the new rings etc and try to get it to prove itself reliable which it did on the day ,starting first flick and running very well with no missfires and very smoothly. When I got home I was very happy with it, It was only on Friday when I pulled the plugs out I started again to fear something is wrong.

I will try to check the compression this Friday and see what that turns up, It could be condensation as I said only small droplets on the plug, but what about the clean one? Paranoia paranoia

Edit
sorry Haventaclue I failed to answer your comments properly in my haste to leave work. When I had trouble before the bottom plug always came out fuel/oil wet.I turned it over with tissue in front of the plugs thinking I would see it soaking wet but it only ended up smelling of fuel I even had a peak with an old gunsons colourtune but it didnt look any different to the other cylinders. It was only obvious when I took the powerhead off immediately after running it to reveal cafe o lait in the exhaust chamber.
I am going to struggle to see what the piston is like as its the bottom one thus obscured by the lower shroud, I may see if i can borrow an endoscope.

[Rapier]

Good luck, am hoping will only be paranoia...Often wonder with the increased level of alcohol in the fuel, is so much more hygroscopic - found spray drops of condensation on the ski twin reed plate after running it (lid off) at ivy lake - at one stage it looked like the fuel / air induction was causing the plate to freeze.

[haventaclue]

This is probably way off,might the bottom carb be running lean? Mind you if it was you would expect to see a clean #3 as well
You have probably done this already.Run her 'till she's hot,immediately pull the #4 plug and see if there is any steam.And when she's hot,maybe give the bolts another bit of a turn.

[floater]

I did wonder about carb setting but as you say I would have expected 3 to be clean as well. Both carbs are only about 3/4 of a turn on the needles. I set it up in the tank, best tickover was even leaner but dies when put in gear any richer than where it is now gives a really lumpy tickover barely able to keep running. As it is the throttle stop screw is further out than I would expect it to be. However it all runs very well so must be set up ok

I have not tried removing the plug hot this time, however when I tried it before all the cylinders were like smoking guns I could not tell if it was steam or smoke.

Forgot to mention. While running at Ivy lake the water pressure gauge was showing about 7 PSI whilst cruising around, I imagine a crack in the jacket would pressurise the system and push this reading up, as the gauge tops out at 15 PSI im assuming 7 is about right. Also if there was a crack in the jacket I would expect the motor to overheat as it would have aerated water in the cooling system like my Evinrude did with a blown head gasket.

Thanks for the ideas its good to have a sanity check

[haventaclue]

When you set the idle,did you do it under load? 3/4 turn would seem to be very lean,IMHO My '69 Merc 800 idles at around 850-900RPM's no load and 650 thereabouts in gear.And 2 1/4 turns out from seat