Outboard engine cooling system question
 

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

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


Off the top.....some small engines have a little scoop adjacent to the
prop which motivates a cooling water flow. No prop, no flow.

Brian Whatcott Altus OK

Outboard engine cooling system question
 

Frank,
Are you sure the hole isn't pugged up?
(Never saw that before - Right?)
Matt Colie

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

Outboard engine cooling system question
 

On Sun, 16 Mar 08, Frank wrote:
I made sure the water level in the barrel was well
above the water intake.

Make sure it's higher than the impeller. There's no mark on the
outside of your lower unit indicating where it is, you'll just have to
estimate. But some impellers won't suck up water if they're above
water level.
Second thing, remove the thermostat. It might be stuck closed. It
won't hurt to run the engine without it. If that's the problem, you
can replace it later.

Rick

Outboard engine cooling system question
 

Should still be a very small amount of water flow even if stuck closed .
There is a small bypass hole to allow a small trickle to pass. I would
recheck the pickup tube from the impeller housing to the power head to make
sure it's plugged in properly at both ends.
Jim
wrote in message
...
On Sun, 16 Mar 08, Frank wrote:
I made sure the water level in the barrel was well
above the water intake.

Make sure it's higher than the impeller. There's no mark on the
outside of your lower unit indicating where it is, you'll just have to
estimate. But some impellers won't suck up water if they're above
water level.
Second thing, remove the thermostat. It might be stuck closed. It
won't hurt to run the engine without it. If that's the problem, you
can replace it later.

Rick

Outboard engine cooling system question
 

On Mar 16, 4:53*pm, "Jim Northey" wrote:
Should still be a very small amount of water flow even if stuck closed .
There is a small bypass hole to allow a small trickle to pass. I would
recheck the pickup tube from the impeller housing to the power head to make
sure it's plugged in properly at both ends.
wrote in message

...



On Sun, 16 Mar 08, Frank wrote:
I made sure the water level in the barrel was well
above the water intake.

Make sure it's higher than the impeller. There's no mark on the
outside of your lower unit indicating where it is, you'll just have to
estimate. But some impellers won't suck up water if they're above
water level.
Second thing, remove the thermostat. It might be stuck closed. It
won't hurt to run the engine without it. If that's the problem, you
can replace it later.

Rick- Hide quoted text -

- Show quoted text -


Thanks for everyone's suggestions. I tried again. This time bringing
the water level in in barrel as high as possible, making sure it was
well above the water impeller. Same thing, no water is expelled. I'm
going back to take apart the powerhead and see if anything is blocked
there. Though, there is no thermostat on the Merc 3.3hp as far as I
know. Again, thanks everyone.

Outboard engine cooling system question
 

Rick, Jim, or anyone else,
Wouldn't the same volume of water flow thru the pump and out the discharge
(part of which would be indicator stream) regardless of the state of the
thermostat ? I had assumed the thermostat merely diverted cooling water to
the powerhead , as needed. I don't know for sure, but would like to know, if
someone can say.
A few years back, my first ebay purchase was for a kit to force a regulated
amount of fresh water back thru the "pee tube" to flush out the outboard
motor. At the time, i was skeptical whether this would flush out more than
just the water pump, but figured what the heck.
I'm still skeptical, so would appreciate it if someone who is familiar with
these cooling system could tell me.

wrote in message
...
On Sun, 16 Mar 08, Frank wrote:
I made sure the water level in the barrel was well
above the water intake.

Make sure it's higher than the impeller. There's no mark on the
outside of your lower unit indicating where it is, you'll just have to
estimate. But some impellers won't suck up water if they're above
water level.
Second thing, remove the thermostat. It might be stuck closed. It
won't hurt to run the engine without it. If that's the problem, you
can replace it later.

Rick

Outboard engine cooling system question
 

The thermostat is in a small housing that the discharge hose is attached to
so it's kind of like closing a valve on you garden hose, water pressure is
still there but can't get out. So if the stat is stuck shut all the impeller
is doing is churning water with a small dribble ...( much like a 90 year old
guy peeing) coming out the discharge tube. The rest stays in the block
getting hotter. Now this is all in relation to a 25 hp merc but I've seen
and worked on some of the smaller and larger 2 strokes and they have been
basically the same. If there is a stat housing it will be a noticeable part
bolted onto the powerhead with a 90 deg fitting threaded into it. If its an
earlier model, early 90's or before if I remember right, the fitting is
threaded into the block , no extra bolt on housing. That style will not have
a stat. Now as Rick said the quickest way to tell if the stat is stuck, is
to take it out and try it. If still no flow then the feed tube inside the
leg may not in position at the powerhead or at the impeller end. That tube
can be a bitch at times to get in place as your working almost blind and buy
feel. Another problem may be the key that locks the impeller to the
driveshaft. I've forgotten that a time or two but usually notice it sitting
on the bench before it's all back together :-) Other than that the only
other thing I can think of is it may have a massive blockage of mud or
whatnot in a 2 part sandwich kind of part that is one side coolant flow and
the other side exhaust flow. It's at the back of the block on what would be
a cars driver side.
Jim
"Garland Gray II" wrote in message
...
Rick, Jim, or anyone else,
Wouldn't the same volume of water flow thru the pump and out the discharge
(part of which would be indicator stream) regardless of the state of the
thermostat ? I had assumed the thermostat merely diverted cooling water to
the powerhead , as needed. I don't know for sure, but would like to know,
if someone can say.
A few years back, my first ebay purchase was for a kit to force a
regulated amount of fresh water back thru the "pee tube" to flush out the
outboard motor. At the time, i was skeptical whether this would flush out
more than just the water pump, but figured what the heck.
I'm still skeptical, so would appreciate it if someone who is familiar
with these cooling system could tell me.

wrote in message
...
On Sun, 16 Mar 08, Frank wrote:
I made sure the water level in the barrel was well
above the water intake.

Make sure it's higher than the impeller. There's no mark on the
outside of your lower unit indicating where it is, you'll just have to
estimate. But some impellers won't suck up water if they're above
water level.
Second thing, remove the thermostat. It might be stuck closed. It
won't hurt to run the engine without it. If that's the problem, you
can replace it later.

Rick

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)

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)