Glenn,

I have always been amused by instructions like those you reference. The
notes usually make it sound as though nothing in the route could be
above the expansion tank (deaereator). - Nice Trick

I'm going to assume you want to know what matters.

The manufacturer is afraid that the disharge from engine may no be able
to push "over the hill".

Just do your best to avoid Big High loops in the routing. The jacket
water pump is capable of pretty good discharge head, and that only
really matters until the cooling system is full. An air bubble would
have to be really something to prevent the jacket water from flowing all
the way through the loop. Lots of the cars built everywhere can't be
completely filled from the pressure cap.

If you have to go up a foot from the engine connections, no big Whup.
Just be sure to bleed the hoses at start up and keep a eye at the
deaereator level for the first few hours.

Good Luck Guy - I've been watching.

Matt Colie

Glenn Ashmore wrote:

OK. The Yanmar 4JH4 is on the stringers, exhaust run to the waterlock and
raw water hose is on the strainer. Now I turned my attention to running
hoses to the water heater at the back of the engine compartment. The
instructions suggest that to avoid air traps the hoses to the heater should
be run below the level of the engine heat exchanger. BUT the inlet and
outlet for the water heater feed is on top of the pump which is at the top
front of the engine!