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Boots Crofoot Boots Crofoot is offline
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First recorded activity by BoatBanter: Aug 2006
Posts: 8
Default overheating 350 merc ... lost

hope you filled it with antifreeze while is was in storage
to stop rust from forming in the cooling system
Capt. boots
"Capt John" wrote in message
ups.com...

canadianjack wrote:
Its a fresh water system ... the boat/motor runs quite

strong so timing
is good however your point on the flushing is good! I

havent had that
looked at. would a flush clean things out or is there

parts
replacement necessary? thanks you've been very helpful

.....

Larry wrote:
"canadianjack" wrote in

oups.com:

I have a 1987 Formula 223 with a 350 merc mag (approx.

390 hrs) and
I've replaced the thermostat and impeller because it

was overheating to
over 200 degrees. The Thermostat did not solve the

problem so I changed
the impeller in the outdrive and the problem is still

there.

It runs at about 160degrees at idle and then at high

speed (40/50 mph)
its still comes down to 160 degrees ... but at the

middle speeds, with
trim lowered, making turns, slowing down etc temp will

reach
200degrees? my oil is pumping at approx 30lbs ... I

checked the oil,
the gauge seems to work fine ( i checked the ground to

it and it
works?) ... wondering what temp the boat should run at

( i thought
approx 160degrees)? any ideas or suggestions? much

appreciated.



Salt water or fresh? Directly cooled or heat exchanger?

I see you're in
Canada, so water temperature isn't much of an

issue...unless someone
wants to go swimming, as I remember..(c;

Does the boat seem to have as much power as it always

did or does it feel
like it's lagging behind what it used to do? That would

indicate,
probably, a timing problem, which will make them heat

up.

87 to 2006 is quite a few YEARS sitting there all winter

corroding up in
the cooling system of a fresh-water cooled block. Has

anyone pulled a
head off to see what the cooling passages look like

inside after all this
time? Imagine running your car V-8 on just water since

1987. Think
it'll need some serious "flushing" if it never had

antifreeze in it, just
rusty water?

--
There's amazing intelligence in the Universe.
You can tell because none of them ever called Earth.


You might want to replace the hose between the water pick up
and the
water pump. That hose is basically a hose within a hose, and
it's on
the suction side. The inner hose can colapse, restricting
water flow.
Try checking the water inlets as well, make sure their
clean. The heat
exchanger could be clogged, pull the end caps off and very
carefully
run a narrow wire in and out of all the passages. Check the
oil cooler
as well (if it has one) it could restrict the system.



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