Blocked water tube

[leishman]

I have a mariner60efi which has a blocked water tube.does anyone have any ideas as to what could cause this and how to fix it.
Thanks

[Xk59D]

Depends where the block is. Strimmer wire is usually a good bet for the tell tale.

It is probably salt or corrosion causing it.

[paddlers]

How do you know for certain it's blocked. Could be thermostat, failed impeller or any number of reasons ?

[Chanchan168]

I cleared mine using 2mm strimmer wire. Ran the motor in a bongo and used the wire with the engine running up the tell tale.

Cleared straight away