where has my water gone?

[Pat]

Last week my Westerbeke w-10-2 diesel quit pumping coolant water overboard. I've changed the impeller and check hoses for plugs. I have not yet taken the heat exchanger off to check for debris from the pencil zinc(s).
also have not check the exhaust elbo.

I'm really stumped. I have a new thermostat to put on tomorrow and am going to fill the hoses of the system & pump in case it's lost it's prime...

Your thoughts and ideas are really appreciated.
Pat

 

[Bill Roosa]

couple of things to check

First and easy things first. Is the thru hull open? is the strainer clogged?
The impeller is good, is it spinning, check the drive belt and if the impeller is slipping on the shaft. Perhaps the key is sheared off.
Pull off the exhaust from the elbow and check for pluggage
Pull the raw-to-fresh water heat exchanger end caps to check the heat exchanger tubes.

If all that checks out then it could be a collapsing hose on the suction side. You would have to check while the engine is in operation.

 

[RichH]

Lots of possibilities ... that most of the other posters will reply.

Sudden loss of cooling flow in engines with cast iron exhaust manifolds is strong indicator of 'slab rust' ... huge platelets of rust breaking loose from the 'wet' side of the manifold and these 'large flakes' partly or totally blocking the cooling water flow ..... only to fall back down (temporarily) to the bottom of the manifold when the engine shuts down. Slab rust is usually found in engines that have their (raw) cooling water drained for the winter lay-up. To prevent slab rust, fill the engine with antifreeze with rust inhibiters when storing long term --- dont let a marine engine 'dry out'.
If slab rust particles are in fact stopping flow, remove the manifold, go inside with a stiff wire to break up the 'large flakes' ... and do a pressure test to be be sure that a pin hole hasnt developed between the gas-side and the water-side of the manifold.

hope this helps