Raw water intake valve - try to operate or not?

[Magnus Wallner]

Hi.

I have a 1992 Merc 5,7 in my 1976 Sea Ray 220. I've had a leak somewhere, been taking in sea water but only (or perhaps mostly is a better word) when running the boat.

Yesterday, it's been getting worse, I found that there is a little hole in the hose between the raw water pump and oil cooler. The hose has been rubbing on the fuselage and finally it rubbed through. It's not leaking to a visible extent with the engine off but with increasing rpm it goes from a trickle to a high pressure stream (at least I know much raw water pump is working...).

I'm about to replace the hose but here's the problem. I would like to close the raw water intake valve (it's a brass body ball valve by the looks of it) but I haven't operated it (had the boat a few months) and I've been speaking to the PO and he never touched it either (had the boat for like 5 years). Is it possible to replace the hose without closing the valve, ie how much water will move flow through the pump? I suspect that the valve might start to leak as well if I start messing with it.

Boat's been run in brackish and sweet water (about 0,7 per cent salt content) so not real sea water for as many years as any can remember.

What do you think - replace hose without closing the valve or take my chances and close it first?

 

[Georgesalmon]

Re: Raw water intake valve - try to operate or not?

Can't you pull the boat out and change it? I would close the valve (read sea ****) for sure. If its brass as you said it should be fine. Although if the hose your changing is above the water line it won't let water in anyway. But you should be able to open and close that valve for safety, it is below the water line.

 

[Failproof]

Re: Raw water intake valve - try to operate or not?

If the valve does not work, it needs fixed. If that line were to break, you need that valve to work. Thats the only way. There is no substitute for safety!

 

[wingless]

Re: Raw water intake valve - try to operate or not?

Attempt to close the valve.

If it doesn't move, then don't force the lever.

On most seacock valves the rotational resistance is controlled by the valve stem gland nut. If the valve won't move properly, then try loosening the gland nut, on the lever stem, under the handle.

 

[Magnus Wallner]

Re: Raw water intake valve - try to operate or not?

The sea **** works. I didn't need to apply much force before it moved but I had to exercise it a few times before it would reach the fully closed position.

This is how the hole in the hose looks like. The roundness of the edges indicates that it has been rubbing for quite some time, perhaps since 1992 - who knows.




I'll be replacing it together with another hose that's damaged from leaking oil from either the starboard bank crank case breather (it was loose) or perhaps even the valve cover (I'll inspect when the boat's out of the water this fall).

 

[wingless]

Re: Raw water intake valve - try to operate or not?

Good!

It should be okay to remove the hose w/ the valve shut.

My preference is to use marine grease applied by hand to the valve sphere when the boat is yanked and rotate the valve 360? to help operation. I also disassemble, clean and lube the valve stem at that time.

 

[Magnus Wallner]

Re: Raw water intake valve - try to operate or not?

Hose is off but I could have changed it without shutting the sea **** as the raw water pump is sitting so high in the boat that it is above the water line. Anyhow it's nice to know that the valve is working properly.