No coolent flow through hot water heater.

[Masterbcobb]

I have 1988 270 Crusaders. Colsed cooling. There is no coolent flow through the hot water heater to produce hot water. Both supply hose and return hose get hot for just a couple of feet.

 

[RicardoMarine]

A common problem with a WH or Cabin Heater not reaching temperature, is where the supply/return of the engine coolant has been derived.

Supply = a port in the intake manifold prior to the thermostat. It must be prior to the thermostat in order to become under mild pressure via the engine circulating pump charging the block with coolant.
The thermostat is holding this coolant back.... thus the mild pressure.

Return = stdb port in the engine circulating pump. This will be under mild negative pressure.

When we "loop" the two, the system becomes balanced, and we now have an adequate flow to/from a WH or Cabin Heater.

No balance.... no flow.

.