lister petter mini twin over heating

[history38]

Went out on boat today, engine running well, all of a sudden cooling water outlet turns to a dribble , then not existent. checked if water coming in fine, checked impeller fine ,.
Any ideas anyone .

 

[doug748]

I had a blocked by pass pipe to the injection, on the exhaust, and this caused a similar sounding problem with associated steam effects.
I can't recall the exact details but, on this engine, it was a c1/2in solid pipe and was blocked with a black gunk.

 

[NormanS]

Poly bag or similar, blocking inlet?