Flushing the engine

[JimPSPB]

I just bought a new Harris Pontoon with a 115 Mercury on it. The instructions for flushing (salt water use) say to flush with the engine off. How does this work? I would think the cold(ish) water for flushing would close the thermostat. If that were the case how would I be flushing the entire engine, heads, passages, etc? I would think the stat would shut off a lot of flow through the engine and I might not be getting all the salt out? Anyone know how this works?

 

[LobbiJ]

Where are your instructions from? And where is it instructing you to hook up the flush water supply?