Sea Water Strainer Question

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Steve Carpman

Just before winterizing the engine on my Hunter 37.5, I unfortunately decided to clean the sea water strainer. The strainer is located on the forward, starboard side of the engine compartment, easily accessible. After removing, cleaning and reinstalling the strainer, I discovered cooling water would not flow through the cooling system. I realized this almost immediately after I restarted the engine, so I do not think I damaged the water pump impellor. My diagnosis was I either had lost the prime on the water pump and/or had air entry into strainer bowl - gasket did not seal. The inlet to and outflow from the strainer are both at the top of the strainer bowl. I tried filling the bowl with water, but maybe I did not add enough water to fill down to water pump. Anyway, I was unable to solve this promlem. Since the boat is being taken out of the water today, I asked the yard to resolve my cooling problem and winterize the engine. Probably $100 I did not have to spend. This sure seemed like a simple maintenance chore, yet I somehow screwed it up. What did I do wrong? What should I have done?
 
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Terry

Same thing happened when I cleaned the ...

strainer on our Genset. I caused the problem when I put the cap back on. I did not get a good seal because the wing nuts had a small amount of corrosion on the threads. When the engine called for water all it got was air. To make a long story short, I cleaned the nuts and added teflon grease to the threads. You should not have to prime the raw water line after cleaning the strainer unless the water from the strainer into the engine drains out past a worn impeller. Terry
 
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Ricky P

Leak Test & A Request

If your strainer is not watertight because of a poor seal on the lid, when you open the seacock (just to be sure, you did reopen the seacock, right? I know I've forgotten some steps in the maintenance process before) and start the engine, water will leak out from under the lid if the water pump is drawing any water in at all. I have two suggestions. First, tighten the wing nuts with pliers. Hand tight is often not enough. Second, consider moving the strainer into the aft bilge section, and attach it to the wall of the bilge. That's were it is on my boat (1994 37.5), and I've never had a problem getting seawater to the engine after opening up the strainer. Now a request... I'm away from my boat but could use the measurements of the opening door on the aft bulkhead in the master cabin. If you are at your boat soon, could you measure the opening for me and post it? Or any other owners of ~1994 37.5s? Hunter doesn't keep this info anymore. Thanks.
 
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Steve Carpman

Bulkhead Dimensions Ricky P

Thanks for the suggestions. Incidentally, I did reconnect and open seacock before starting the engine. Although I checked the gasket on the strainer cover and it looked in tact, I did not tighten the wing nuts with pliers. The suggestion of moving the strainer to the aft bilge area is interesting. On the 1991 37.5, the strainer is mounted high on the forward part of the engine compartment wall. Although I did not check when I was on the boat, I am confident that the strainer is above water line. Dropping it down next to the seacock is worth looking into. Question, is it safe/recommended to have a glass bowl that prevents sea water from entering the boat below water line? I will be on the boat next week end to put the cover on. I will check your dimension. Is it safe to assume the "aft bulkhead" you reference is the one that separates the aft cabin from the compartment that houses the fuel and holding tanks.
 
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