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Bruce in Bangkok[_5_] Bruce in Bangkok[_5_] is offline
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First recorded activity by BoatBanter: Mar 2008
Posts: 272
Default Outboard engine cooling system question

On Sun, 16 Mar 2008 07:29:09 -0700 (PDT), Frank
wrote:

I have a Mercury 3.3hp 2 stroke engine that fell into the water last
season. When I recovered it I disassembled it and cleaned or replaced
every part. I put everything back together, brought the engine
outside, put it in a barrel of water and started it up. It started up
fine after a few pulls and appeared to run great, until I noticed that
no water was being expelled from the tube leading to the powerhead.
The manual calls it the water pump indicator hole.
I immediately stopped the engine of course to avoid overheating. I
then took apart the lower unit, replaced the water impellor and
gaskets. Upon starting the engine again, still no water was being
expelled.
I verified that the water tube connecting the pump housing to the
powerhead was clear of debris. I verified that the water tube in the
shaft was properly seated in the pump housing when I reattached the
lower unit. I believe I installed the water impellor in the correct
orientation. The powerhead should be clear, I disablembled and cleaned
every component. And I made sure the water pump indicator hole was
clear.
I can't for the life of me figure out what could be wrong with the
cooling system. I made sure the water level in the barrel was well
above the water intake. When the engine was running the water tank was
bubbling up quite a bit ( no prop) so I assume the impellor was
working. Anyone have any ideas what could be wrong. Any guesses whould
be appreciated.

Frank


First of all:
Are you sure that the key is installed with the water pump impeller?
Is the impeller in right and not broken?
Are you sure that the rubber seal that seals the water tube into the
pump housing is installed?
Did you clean any salt deposits out of the cooling passages when you
had the engine apart?
The cooling water pipe did go into the top of the water pump when you
installed the lower end?

Look at the leg just a bit forward and above the propeller shaft and
there are some little holes in both sides of the leg. Clean them out
if they are blocked.

Take the plastic tubing off the power head and make sure that the hole
in the casting is clear.

The Forward - neutral shift lever shaft is in the water stream from
the pump to the engine, if it is leaking then there is diminished
water flow. It has "o:" rings on each end, if I remember correctly.

If the above is correct then there ain't anything else. Go back and
fix whatever you did wrong. ..

The 3.3 (I've had one for years) is fairly forgiving about cooling. I
don't mean to run it and run it with no water but it will run for a
few minutes without damage.


Bruce-in-Bangkok
(correct email address for reply)