searay470
 

i have a 1980 searay flybridge cruiser with 2 mercury marine 470 both engines have less than 600 hours i have flushed every water hose on the system coolant an seawater also new pumps in the lower unit an new thermostats also cleaned the dual pass water coolers, i can run the engines at 2000 rmp an not have a heating up problem, if i push it up from there it will get hot, my question is who knows what i need to do to get it to run in normal heat range at higher rmp???

the hose inside transom assy? and check the fitting at top of that hose?

searay470
 

yes thankyou, what i have done with the hose from the transom is this i put a water hose in the transom water hose let it run water from inside or at the cooler it flow out of the prop in good flow also i sacrificed a pair of seawater pumps and had the lower units in some water with the hose unhooked from cooler then stared it to see how much water it was pumpin into the cooler the amount of water comin in was strong, so thats nall i know forsure on that

Are these the old merc 4 cylinders? Had a buddy that had a pair that overheated at anything over 2,000 rpm- ended up being head gaskets..

the 470 is the half a ford 429. 460 iron ford head. on merc built aluminum block. good idea in some ways, bad idea in some ways.

these are closed cooling. are you loosing coolant?