Help please ,I have a 1987 baja boat with a 165 hp mercrusier motor
with a closed cooling system.It runs great but wants to overheat at
high rpms over4000 at 3000 it is as cool as can be about180 .30
seconds at 4000 or over it shoots up .If i drop back to idle it cools
right back down but I would like to tow a skier or tube for more then
30 sec.Any ideas would be gregtly appreciated .Also why do i have what
looks like a power steering pump on this thing and is there any
connection to the cooling .thinks greg

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On Jul 29, 5:22*pm, greg40391 wrote:
Help please ,I have a 1987 baja boat with a 165 hp mercrusier motor
with a closed cooling system.It runs great but wants to overheat at
high rpms over4000 at 3000 it is as cool as can be about180 .30
seconds at 4000 or over it shoots up .If i drop back to idle it cools
right back down but I would like to tow a skier or tube for more then
30 sec.Any ideas would be gregtly appreciated .Also why do i have what
looks like a power steering pump on this thing and is there any
connection to the cooling .thinks greg

--
Posted at author's request, using moderatedhttp://www.BoatForumz.cominterface
Thread archive:http://www.BoatForumz.com/help-im-br...pict21242.html

Change the thermostat and do a pressure test on the cooling system..
If that doesn't work check the timing..

greg40391 wrote in news:149596_
:

Help please ,I have a 1987 baja boat with a 165 hp mercrusier motor
with a closed cooling system.It runs great but wants to overheat at
high rpms over4000 at 3000 it is as cool as can be about180 .30
seconds at 4000 or over it shoots up .If i drop back to idle it cools
right back down but I would like to tow a skier or tube for more then
30 sec.Any ideas would be gregtly appreciated .Also why do i have what
looks like a power steering pump on this thing and is there any
connection to the cooling .thinks greg


The heat exchanger's clogged and unable to cope with all the extra heat
guzzling up all that extra gas at 4000 RPM creates, so it loses the battle
until you stop overloading its dimished capacity.

Take the heat exchanger to a radiator shop and have them cook it in acid to
clean the passages back out so it will cool better.

The primary water pump could also be at fault. When did you replace the
impeller last?

"greg40391" wrote in message
news:149596_6fcc5012e718b97db2704235335c034b@boatf orumz.com...
Help please ,I have a 1987 baja boat with a 165 hp mercrusier motor
with a closed cooling system.It runs great but wants to overheat at
high rpms over4000 at 3000 it is as cool as can be about180 .30
seconds at 4000 or over it shoots up .If i drop back to idle it cools
right back down but I would like to tow a skier or tube for more then
30 sec.Any ideas would be gregtly appreciated .Also why do i have what
looks like a power steering pump on this thing and is there any
connection to the cooling .thinks greg

--
Posted at author's request, using moderated http://www.BoatForumz.com
interface
Thread archive: http://www.BoatForumz.com/help-im-br...pict21242.html

180 is not cool on a boat. It should be around 160. When was the last time
you replaced the outboard impeller? Otherwise you may need to remove and
flush your heat exchanger.

You probably do have powersteering. And that's what the pump is for.