Just spent 3 hours sweating over my engine changing the seawater pump impeller. On the little Sole I need to remove the heat exchanger to get at the seawater pump. Here is how it went!
Arrive at boat at 1115. Open up and clean a little bit (about 1 litre) of water out of the bilge, not bad after the rain we have had for the past two weeks.
Remove engine cover (cabin table).
Unscrew all the heat exchanger clamps, prise the exchanger off.
Dry bilge of rusty coolant.
Remove the impeller cover, six small allen headed bolts, drop allen key into bilge twice.

Glad I had cleaned the bilge first.

Try to get the impeller out, won't budge,

have a drink of water while I think about it. Crank engine over, impeller moves out. Lever it a bit more and crank again. Get impeller out.

Line new impeller up with the key way and push it in. Won't go. Get down on cabin sole with torch and see I have put it in about 30 deg out.

Remove and realign. Spend 30 minutes getting it to go in.

Find gasket goo. Top has rusted through and it is a sticky mess inside a zip lock bag.

Get enough goo to coat the gasket face on the cover.
Replace cover with the six bolts, drop the allen key into bilge once. But skin fingers getting the little bolts finger tight. A unpleasant job in the cramped space between the cover and the starter motor, holding torch with right hand and use uncoordinated left hand to use the allen key.

Replace the heat exchanger and tighten up what feels like two dozen clamps. Really only 6 but have to do them twice and check all the others.
Open inlet cock, hear rushing water,

engine cock off, find leak and undo then redo the clamps. Cock back on, no water ingress. Very pleased.

Put water in coolant tank, listen for leaks. Silence and nothing in the bilge.


Start engine. All good. Add coolant concentrate and more water.
Run engine, looks good.
Drop mooring and go for a 20 minute drive.
Minimal water in bilge, probably a bit of overflow from me topping the coolant a bit high.
Clean it up and run engine again for 5 minutes. Dry bilge.


1415, clean up and go home.
Is this what all boat owners go through? Why can't it be straightforward?