19. Re-plumbing raw water cooled engines for better hot water heater performance

This re-plumbing scenario works well for increasing the water temperature reaching a hot water heater. As you sort through the steps, you'll see that the main change involves intercepting the water for the hot water heater as it comes out of the thermostat housing (where it has just been heated by the block and the head), and redirecting the cool bypassing water from the "T" fitting in the center of the water jacket side plate directly to the front fitting on the manifold.

ALTERNATE PLUMBING FOR HOT WATER HEATERS IN LATE MODEL ENGINES:

1) Remove the bypass hose between the "T" fitting in the center of the water jacket side plate and the inlet to the thermostat housing.

2) Install a 3/8" pipe plug in the inlet to the thermostat housing.

3) Remove the short hose between the thermostat housing and the inlet to the manifold.

4) Connect a hose from the outlet of the thermostat housing all the way to the inlet of your water heating device.

5) Remove the 90 degree elbow from the front of the manifold, and install a "T" fitting in its place.

6) Connect the return hose from your water heating device to one side of the new "T" fitting in front of your manifold (it doesn't really matter which leg of the "T" you use in this step).

7) Connect a hose between the outlet of the "T" fitting in the center of the water jacket side plate and the unused leg of the new "T" in front of the manifold.

8) Install a ball valve somewhere in the hose installed in (7) above.

The valve in this new bypass loop should be closed down just enough to provide a small amount of back pressure downstream from the "T" fitting in the center of the water jacket side plate. This back pressure will provide enough preferential flow through the block and head to enable the thermostat to maintain your original temperature. Care should be taken to not close the bypass valve too far, as this will cause overcooling of the engine. - Updated: January 20, 2004