Watery plugs

[broadbent]

I couldn't start my engine - Mercruiser 4.3L - and found that the plugs were wet. Especially those aft.
Any ideas where to start looking?

The engine is from 1991 and has been stored in a garage for the last 3/4 years. Before that in salt water on east coast.

 

[mtb]

Wet as in water wety or petrol
If water could be head gasket, cracked head or other major fault .
If petrol could be low compression due to rings stuck in piston grooves .
Was this the one that had been stored for some years in a shed!!, some one had just got one not long before xmas.
Mick


http://homepage.ntlworld.com/boats
I want a big steel ex trawler / tug v / cheap or swap for tug

 

[broadbent]

wet as water

 

[yoda]

Water only gets into cylinders and hence on to plugs from 2 sources. Condensation or leaks from the cooling system. If you know it's not condensation then it's off with the head to investigate. Since you tried to turn the engine over I take it there is no other obvious failures and that it turned over smoothly. If you have large amounts of water in the cylinder on the compression stroke it could do untold damage. If indirectly cooled then check the header tank to see how much water is left. If still full then check plugs are working correctly, drain carbs and check there is no water in fuel tank and retry. Other than that we need more info to do an at range diagnosis. E-mail me if you want.

Yoda

 

[broadbent]

How can I tell if its condensation.

Might it help to know that the week before I put it into the water and it staretd up immediately, as it did the next day.
However I did have problems at idling speed and it needed to be revved up at 1200rpm.
When I came to put it back on its swing moorings, it kept stalling and I couldn't get it into gear, so i was towed back to the mooring. A week later it refused to start.

I ought to add that I know nothing about engines, but would like some information before geting a mechanic.

 

[ccscott49]

The best way to check if you have a water to engine leak, is with a coolant system pressure tester, which will show you in a matter of minutes. Normally, coolant leaking into a cylinder only happens when the engine is not running, when its running the pressure of the combustion overcopmes, easily, the coolant system pressure, so you normally see it before hand. However it sounds suspiciously like you do have a problem with the coolant, pressure test it. Or it might be time to bite the bullet and call an expert.

 

[yoda]

This now sounds more like a problem with water getting from the cooling system into the cylinders. If you wish to remove the possibility that water is getting into the cylinders from the fuel system there is some good tank additives on the market which solve the problem very quickly. Almost worth doing anyway just to be sure. If you dry the plugs off are they wet again before starting or can you get the engine going? If they dry off, engine starts and then starts to fail again then you will need to investigate the cooling water system.

Yoda