Mercruiser 43 idle overheat problem

[danchovy]

"Me 1990 4.3 gets up to 260 at

"Me 1990 4.3 gets up to 260 at idle but runs at 150 at all other rpm's including 4500. Have changed hoses, impeller, circulating pump, thermostat, riser and header gaskets, cleaned line from oudrive all the way to the engine intake. Even changed the sending unit and guage. Any thoughts??}"

 

[bondo]

"Ayuh,......

My 1st WAGuess

"Ayuh,......

My 1st WAGuess is,......

The Impeller Housing might be Scored, so it's by-passing, instead of pumping at Idle......"

 

[fastjeff]

Or an air leak before the raw

Or an air leak before the raw water pump.

Jeff

 

[mistahays]

is it FWC or RWC?

is it FWC or RWC?

 

[bill999]

"worse case scnerio is raw wat

"worse case scnerio is raw water pump assembled incorrectly. Impeller veins reversed or gasgets or o rings or seals incorrect causing a leak. If you get as far as getting back to the pump, before removing pump, pour water down the exit tube and see if and where water is leaking out of the pump assy. A dribble is ok a gush is bad."