Quote:
Originally Posted by Rockter
If you are improvising a coolant supply with a hose when your boat is on the hard, make sure you switch off the hose before you stop the motor, and don't turn the hose on until the motor is running. You must, or the motor just floods a few of the cylinders to the brim with water. If it happens, your first warning will the heart-stopper of seeing water dripping out of your air filters. Don't dispair, but don't start the motor. Pull the injectors out (not the biggest of jobs) and suck the water out, by mouth with a drinking straw if you must, or use a wee oil lift pump, or something. I have had to do that for other reasons.... not the hose error.... but an error nearly as bad.
The motor is still running well, 11 years on.
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Sorry but NEVER, NEVER, NEVER connect any PRESSURIZED hose directly to a marine engines raw water intake RUNNING OR NOT!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!
Many boat yards and marinas are on city water supplies with "street pressures" in the range of 100 PSI and 6-10+ gallons per minute. If you don't hydrolock the engine you will blow out the seals in the water pump. Connecting pressurized water to an inboard engine is a HUGE NO NO..
You should ALWAYS use an in/out bucket and let the raw water pump do as it is designed to do suck water at it's own pace and flow rate. Remember raw water pumps are driven off the engine and move less water at low RPM and more water at high RPM. At low RPM most hose spigots will overcome the flow rate of the water pump, unless you have a very, very weak water supply. The pressurized water from the hose will fill the waterlift muffler and then back up into the cylinders. If this happens when the engine is running you can do serious damage to the engine as water is NOT compressible. I tried to talk a guy out of doing this a few years ago when he ame over to borrow my hose, but he "knew everything". I even offerd to set it up and get it running for him as I had my in/out bucket kit with me. About 45 minutes later he came back with his tail between his legs and about 12k lighter in the wallet. He had hydrolocked his engine at 1800 RPM while attempting to test fire it before launch. Needless to say he never launched on time..
In a gravity hydro-lock or one that occurs with the engine off it is a fixable event though it will take 6-12 oil & filter changes, depending upon the engine, to fix the issue. The valve cover should also be removed as water can get trapped up there despite numerous oil changes.
Always use an in/out bucket. Also if your in/out bucket is located in teh cockpit and is higher than the engines siphon break it will siphon after shut down and can still hydrolock your engine. ALWAYS pull the hose from the bucket it is sucking from and let it clear the water before shutting down the engine..
The clear hose goes straight to the sea strainer and sucks from the bucket. The yellow hose is a garden hose and keeps the bucket full. This prevents connecting direct PRESSURE to the raw water pump...
Having worked in boat yards I have fixed hydro-lock events and seen many of them destroy engines. A fair amount of them were caused by un-informed owners connecting pressurized water hoses directly to the engine.