plantsman wrote:
You might also check for a blown head gasket. Your symptoms sound just like
a van engine that I had. The exhaust was pushing out all of the coolant
resulting in rapid overheating. Just a thought.

David Sizemore

"saltare" wrote in message
y.com...

I have an 85 Supra Saltare witha PCM 454 Chevy inboard engine that is
overheating as soon as it gets revved over idle speed. I have replaced
impeller, thermostat, and water pump with no change. I know the hose is
clear from the impeller to the water intake under the boat, because I ran
water from the impeller down to the water intake, but it doesn't appear to
be taking the water in up to the impeller. I checked this by unhooking

the

hose from the impeller to the thermostate housing and its not getting any
water. I know the impeller is turning i.e. turning gear operates

correctly

and belt is not slipping. I am at wits end. Does anyone have any ideas?


Thanks

Saltare






The water leaves the water circulation pump, goes along each bank of
cylinders to the rear of the block, then & only then (save a few little
bleed holes along the way) can it get up into the heads, where it
travels along each to the front & out into the manifold/thermostat housing.

The holes at the rear of the block/head are not all that big & are the
"tightest" part of the flow pattern so if they become corroded or as
already suggested, blocked with debris (alive or dead) the flow can be
stopped, notwithstanding the additional raw water pump.

Take the thermostat out & the inlet hose(s) off, when see if you can
get good flow backwards by putting a reasonable pressure & flow hose in
where the thermostat was. (Not too much pressure)

If you get resistance or worse actual blockage, take the water
circulation pump off & see if that uncovers anything that can be causing it,

If it's still blocked, before you go too far, try pulling a couple (one
each side) of strategic welsh(core?) plugs so you can get a better feel
for what's stopping it.

Last resort pull the heads off & see.

K