Replacing impeller when stopcock seized

[Ramona]

I would investigate why there is a reduced water flow. May not be the impeller but a calcium build up after the pump.
Pull off the hose after the pump and start the engine. Check how much water pumps into the bilge. Just run the engine for a few seconds. Reinstall the hose and pull off the hose where it goes in to the exhaust elbow. Start the engine again for the same period and compare the water flow. You may just need to run some acid through your system. Watch a couple of Barnacle Buster videos.

[MickB]

Originally Posted by boatpoker

Again..... this forum needs a "LIKE" button.

Ditto

[Library70]

Sounds like we're talking about a saildrive?
If it's a Yanmar SD50 or earlier model, you may never get the seacock unstuck. Once they seize they are a bear to unseize. They are a screw type valve intended to torment whoever might use them in saltwater. I mutilated and replaced two of them,now I exercise them every time I check my engines. If you grind a slot in a 3/8 drive deep socket and slide it over the cross arm it might help you loosen it-or break it. If your sea strainer is above the water line you can loosen the cover so that water won't siphon in when you open the raw water pump, if you have a vented loop it will do it for you.
I agree that your water flow problem could be growth in the water passage.

[stnick]

Replace the seacock , Get rid of the ball valve ! Are you saying a Farr 40 is made with ball valves ? Maybe you just have a jammed sea cock . spray with PB blaster a couple times a week than tap it. ! All the best

[Icarus]

I think a lot of boat owners are very helpless when it comes to basic maintenance or trouble shooting, what ever happened to self reliance and living off grid?
This boat owner doesn't even know if his engine is below or above the waterline!
Stands to reason to fix the seacock, I would slip the vessel and check and replace all the seacocks if they are found faulty.
To check and replace the impeller just clamp the water intake hose.

[lituya1617]

Low water flow through a frozen seacock is a serious problem. You should fix the valve or replace it. The pressure of sea water at the hull fitting is minimal and the valve can be removed without risk of sinking. Just make a plug out of wood for the opening and insert it when you unscrew the valve. If you run seawater into the bilge, put some seawater active detergent in with it so you do not grease up your bilge by flushing out under the engine. Also, the discharge of oil from your bilge pump could get you a huge fine so use a lot of Joy. Marine growth is more likely than an impeller to be slowing water flow. If you have plugging from marine growth, you can rod it out when you unscrew the valve unless there is an external strainer but even then running a big screwdriver around in the pipe will get rid of most of the marine growth (and deposit it in your boat). Your cooling water inlet should have a filter on it. You need to make sure the hoses are clear and the filter is clean. If you want to change the impeller make sure you inspect the inside of the pump body. If the pump body is scored or very worn, you may have to replace the whole unit. A new impeller is not always the answer. Be sure you also check the lines leading out of the pump to make sure some clams or whatnot have not plugged them. There are specifications for how much water the pump should pump, get a bucket and catch the exhaust outflow for a measured minute.
This is the only way to actually measure the pump output. Make sure you do this test at the RPM the engine manual specifies both before and after undertaking repairs. Good luck. As usual, nothing haywire on a boat is simple.

[epatant]

I would check the flow through the saildrive: have had jellyfish in intake, barnacles living in the intake and pipe, and the inbuilt stopcock is seized for years.
I dry out twice a year and use a welding rod to clear out the leg intake, have installed an email n line stopcock just upstream of the leg stopcock. Last time I replaced the membrane when u dropped the lower leg the void through which the water passes was about 70% full of cluster of small barnacles!
I always blow Back water from a hose connected to the water outlet on the leg to clear any developing blockage when I dry out..
If you clamp the intake hose u can easily replace the impeller with n the water. I would attach a hose with the end in a bucket of water to check that all is well with the pump and from the pump onwards.
Would be wary of going to sea without a shut off valve on the intake.

[Trawlerman]

I am not sure if I missed the info, but is your stopcock a ball valve type or the old conical type? If the old conical type, then you can loosen the jam nut and then the tension nut on the end of the cone far from the handle, and tap that far end and drive the cone out a bit thereby loosening it. I hate these old stopcocks, but there are still lots of them out there. I had all mine changed to ball valves.