Penta AQ205: sealing sea water hoses so I can take the head off whilst floating?

[loco]

Long story short: we think the timing was off which has lead to pre-ignition and a plug melting. The core of the spark plug is missing, and now we have zero compression in that cylinder, so we suspect a damaged or broken valve and need to take the head off to see where we go from here.

Craning the boat out the water is seriously expensive, and we don't know how long it will take to get the head fixed or the block, if it's that that is damaged, but we do have the option of a drying pad, which is free (as the tide goes out, we can sit the boat on a pad for a few hours to work on it). The pad is 20m from the mooring, so my plan was to go to the pad, plug the inlet hoses for the sea water and exhaust, then tow the boat back to its mooring. Once we've fixed the head, we can do the reverse.

The engine's an AQ205, so has a big seawater pump with an inlet hose (easy to plug), but what about the exhaust? Can I just take the exhaust mainfolds off and plug them too? Anything else I need to consider?

As always, many thanks in advance for your help.

 

[Howard Sterndrive]

Re: Penta AQ205: sealing sea water hoses so I can take the head off whilst floating?

you probably have a seawater **** - simply shut it off. if not, just clamp a 3/4 extension or other similar solid object in the line. You can buy a bag of emergency dowels at most marine shops.

The only other entry point would be exhaust if wavy. After you remove the manifolds/risers, find a PVC or ABS cap at the hardware store and clamp it in the exhaust hose... build the plastic plug up with electrical tape if you can't find the right dia.

If you have closed cooling, be ready with a shop vac or towels so your bilge pump doesn't pump glycol overboard