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

In article m,
says...
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

If you know the intake side from the thru hull is clear and you know the
outflow is clear from the seawater pump is then the impeller key may be
sheared.

Sounds like the impeller isn't impelling.

Check for loose hose clamps on the suction side. Check impeller carefully.
Sometimes the rubber loses bond to the hub. Pull at the rubber to see if it
is bonded to the hub. The seal in the pump behind the impeller could be bad.
The pump cover could be worn enough to cause an air leak.
Jim
"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

On Sun, 16 Nov 2003 22:33:00 GMT, "saltare"
wrote:

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


I'm not familiar with this particular set-up, but it seems that
something has been missed.

Is there any way the water pump could be turning backward(or a wrong
handed pump)? Are there any check valves that might
malfunction(thermostat)? Is everything plumbed correctly?

Look things over again and try to rationalize how a pump that is
supposed to be getting water won't pump. This isn't rocket science...
something in the train of logic is flawed.....

It sounds as if you have looked at most of the usual causes. The
symptoms sound very much like what can happen with Zebra Mussel
infestation throughout your cooling system.
Was your boat left sitting unused in the water for a couple of weeks? If
so, that's all the time it can take for a colony to grow large enough to
clog your system. For your sake, I hope that you find a simpler
explanation for your problem, because the Zebra Mussel problem usually
calls for a tear down in order to get rid of the little devils.
Good luck and good boating,
Jim

saltare wrote:
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

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

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

"saltare" wrote in message news:wWStb.164

I checked this by unhooking the
hose from the impeller to the thermostate housing and its not getting any
water.

So, with the outlet hose from the raw water pump disconnected, and the pump
turning, no water comes out?

And you know there isn't a blockage between the pump and the water intake?

Then I would say that there is a large air leak between the pump and the
water intake, or a serious block right at the pump oulet.

Another possibilty comes to mind: Is it possible that while investigating
the problem you reassembled the water pump wrong? Could you have swapped
intake and outtake on the pump?

I would suggest getting a length of hose that will fit the pump intake and
running an experiment. Disconnect the existing hose, hook up your
experimental hose. Drop the free end into a bucket of water, and see if it
will pump that. Also, try disconnecting the outlet hose right at the pump.

Rod McInnis

Problem solved!

Thank you for your helpful responses.

It turned out that the replacement impeller purchased at Ebasicpower online
was not the proper thickness. Once I replaced the impeller with a "fatter"
impeller and it pumped water immediately and overheating stopped. The
thinner impeller was not generating enough suction pressure to pump the
water out of the lake.

I noticed that the Ebasicpower impeller was thinner, but I figured they knew
what there were selling especially since i bought another one later as a
spare and it was the same size. This company has been aggravating since the
thermostat I bought from them did not even remotely resemble the my
thermostat even though I gave them the correct specs of my engine.

Also, last year a starter I purchased from them went kaput as well. The
metal around the pinion gear shatterred, causing me to pick the pieces out
on my flywheel housing.

I am finished with this E-retailer and probably with any mail order boat
parts. Its definitely worth paying more at your local boat shop to see the
parts when you buy them for correctness as well as quality.


Saltare

"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

In article , saltare2000
@yahoo.com says...
Problem solved!

Thank you for your helpful responses.

Impeller wasn't impelling.