Re: No cooling water
My 454 w/ Bravo1 did same thing. If a cheaper after market pump or impeller are used, sometimes they fail to pull a suction properly. Also, if there is any wear at all on the pump housing / impeller, the same can happen. When I used Mercruiser parts, the problem also went away, for the most part.
Since having had 2 plastic pump bodies crack and leak on my setup, I have since converted mine to a Hardin Marine all stainless steel pump.
Stainless Steel "Lifetime" Sea Pump Overhaul Kit - Hardin Marine
This thing is awsome. The old plastic pumps, once flow was established, seemed to run fine on the hose, but this beauty of a pump actually sucks the old hose down telling me it is pumping far better by pulling more water through the hose than the plastic ones did. I had to get a bigger hose to run it with the volume this pump wants, even at just over idle. Another plus is when, using the plastic pumps, when I came off a full power run, my engine temp would climb pretty quick then gradually come down. With this pump, that doesn't happen to any where the extent it did before.
Figuring in the economics of it, this pump cost the same as 3 or 4 plastic ones, BUT should last a lifetime. How many plastic bodies will it eliminate replacing, paying for itself over time and actually saving money. Especially for me, since I normally replace the impeller every year and the body when it needs it, which seemed to be every one or two years. More often if it cracked or ran w/o water for what ever reason. Plastic bags kill em in seconds, I know. The bags will still kill my impeller, but this S/S body will survive the incident where the plastic ones will blister and burn up the interior sealing surface of the pump body next to the inlet / outlet connections. Another plus... It uses std Mercruiser impeller.
Only minor problem I had with installing it, the hose connections extend a little further out, causing the inlet hose to hit the stbd motor mount. Cured that by using the 90 degree S/S fitting on the inlet side of the pump and cutting the 90 degree bend off the hose and clamping it on straight to the fitting. Nice clean install.
