36Tango

I have a 377 Scorpion with a seawater pump, a circulating pump, Lightning tube headers that are dry to the tips. I have a pressure valve in between the seawater pump and the circulating pump that begins opening at about 15 pounds and is fully open at 35. I have a thermostat housing with lines that feed the headers. We have drilled a couple of small holes in the t-stat so that the headers still get water when at idle. Too many holes, the engine does not retain any heat and will not open the t-stat at idle, but the headers stay cool. We are to where we have two small holes in the tstat, still get water out of the headers, but the headers are hotter to the touch. When backed in on the trailer, it will idle up to about 130 degrees. I am sure that once on the water, the thermostat will open and things will be good, but I think that I would like to be able to get an open tsat at idle on the trailer. Do I? I think that we are at a happy medium right now, but need suggestions.

Should I divert some water that comes out of the pressure valve directly to the headers (bypassing the tstat) to cool the headers? Should I just be happy with what I have knowing that it wont get over 135 degrees at idle?

Any thoughts?

Boat1

Please provide a better description of the complete system and describe all the hoses going to the thermostat housing. Flow should come from the raw water pump through a fuel cooler then oil/power steering cooler then into the thermostat housing. The circulating pump should draw from the thermostat housing. The thermostat housing also will provide the by-pass function to cool the exhaust when the thermostat is closed. It should have four 1" hose outlets that go to the exhaust, one 1 1/2" out to the circulating pump, and one 1 1/4" inlet from the raw water pump. The pressure relief valve has no effect below 15 psi and you will not see this much pressure at 1300 rpm unless you have a closed thermostat and no by-pass.