Blackhawk Freshwater cooling

[evetsathom]

Earlier this year I had a freshwater cooling system installed on my 96 Blackhawk. I purchased it from San Juan Engineering. Prior to the install the boat ran at a temp of about 180, slightly higher while pushing it. After the install it runs @ 200 at a cruise speed and higher once you get it over 3000 rpm. Last weekend I had to pull back to an idle from high speed. The hot buzzer came on immediatelly. The mechanic that installed the unit thinks that the pickup on the blackhawk unit can not take in water fast enough to keep it cool. He wants to install a through hull fitting. The idea of butchering the boat turns me off. Any thoughts as to what may be the solutiion ?

[evetsathom]

Scott The sea water pump was the first thing we replaced. It looked worn but the new one made no difference. I'm not sure if it is a full of half system. I drive it and hire a mechanic to work on it. I relied on San Juan to provide the correct size unit. They asked a bunch of questions during the purchase. They appeared to be quite informed and seamedm to know what they were doing. I can check on the t-stat but it was a new one that came with the kit/

[RedDog]

For what it is worth, my '98 502 MPI (same as yours?) is raw water cooled and runs at 150 - 155. Quite a bit lower than your pre-closed (what you call fresh) cooling temp of 180. Maybe a new thermostat should be tried? Check the impeller?

[Lenny]

also keep in mind that San Juan has probably never seen a Blackhawk drive in their lifetime if they only look at local (West Coast) stuff...not that this helps but as an ademdum... :)

[Greg Maier]

I think you should get hold of BigGrizzly here on the board. I think he had a custom made FW Cooling system made for his Donzi. From reading his posts, he seems to have an advanced knowledge of this topic .

[MOP]

evetsathom check #14 in the post below have your man do the tests, it is fairly and not to time consuming this verify your water flow. I would also put a pressure gauge in the sea water circut on the outlet end going to the risers. It is very possible that over time the risers be they Iron or Stainless may have gotten plugged up a bit. My gut hunch is check how fast the water is getting out not in.

Phil

http://www.donzi.net/forums/showthread.php?t=35970

[Bad-Tat]

I have that full system on Bad-Tat and it runs 180 at all speeds. You must have a blockage somewhere in the system. Oil cooler or manifolds if not full system?