On 26 Apr 2004 15:06:00 -0700, (Chris) wrote:

OK, I am a new boat owner and am learning the hard way. I am pretty
sure that I have fried the water impeller in the stern drive. I have
an '81 Glastron SX-190 with a Mercruiser 228hp 305. I didn't know,
until now, that the boat should never be started even for a few
seconds without water supply at the stern drive. Well sure enough, I
got the boat out to the lake for the first time this year and I have
an overheating problem. I took out the thermostat at the lake
thinking that maybe it was the culprit. Still the boat overheats at
idle. When I rev the engine to about 2000 rpm, it cools back down.
The only thing I can think is that the impeller is not working at idle
speed and barely working enough when I get it up to 2000 rpm. Does
this sound like the impeller is working poorly or could it be that I
need to put in a new working thermostat? The stat that I took out was
140 degrees. Is this too cool or the right one for this engine? Any
info would be appreciated. I am good with cars but am learning
quickly that not everything I know is true anymore (i.e. cranking the
engine and running it without coolant for 5 seconds is NOT acceptable
like it would be with a car). Any other things I should be aware of
would be appreciated. Also, there appears to be quite a bit of
voltage loss in the 23 year old wiring. I am thinking about rewiring
the boat. Any advise or horror stories?

Chris

Give us symptoms and numbers, then someone here will supply
judgments for you. A 140 thermostat is OK.
"Over heating" means - steam coming out of the valve cover?
Temp gage reading?

5 Secs out of water is not always the kiss of death to the impeller,
it could be much much worse things are wrong!
:-)

Brian W

"Chris" wrote in message
om...
OK, I am a new boat owner and am learning the hard way. I am pretty
sure that I have fried the water impeller in the stern drive. I have
an '81 Glastron SX-190 with a Mercruiser 228hp 305. I didn't know,
until now, that the boat should never be started even for a few
seconds without water supply at the stern drive.

Yep, true, never ever run the engine without a flow of water!

Of course, this is a "do as I say, not as I do" thing. I always hit the
starter before I get to the ramp just to make sure that the boat will start
when I get it to the water. Crank, Start, shut off! Not a good idea, but I
do it anyway. I get three or four years out on a water pump impeller.

Your boat is an '81. Any idea when the impeller was changed last? How many
hours it has on it?

It was possible, indeed likely that the impeller was on its last legs when
you bought the boat. There are two approaches to changing your impeller:
one is wait until it fails, the other is preventative.

On my ski boat, I can change the impeller with only a screw driver in about
10 minutes with the boat in the water. I carry a spare impeller at all
times, just in case (I have also sucked up weeds that chocked off the water
supply and caused the impeller to burn out). For me, running it until it
fails is not a big deal.

Not sure about Mercruisers, but some I/Os and all outboards the water pump
is in the lower unit. You don't want to be changing the impeller with the
boat in the water. Having the impeller fail can ruin your day, weekend or
even life if you happen to be off shore when the water pump fails and you
can't fix it. In such a case, changing the water pump impeller every year
or two is a good idea.

Rod

Alright, the consensus sounds like I should start with an impeller
replacement. Will do, especially since it sounds like a maintenance
item anyway. If that doesn't work, I'll start looking for other
restrictions in the cooling system. Just to clarify, when I say
overheating, I mean that the temp gauge was pegged and the exhaust
smells of burning oil. The gauge goes up to 240 I believe (I'm not on
the boat right now). When I would rev it and get it to cool down, it
would get down to about 160-180. I have no idea when it was last
replaced so it may have been about dead anyway. I will replace the
thermostat with a new one too instead of putting the old one back in.
It looks just like a standard auto thermostat. Is there any
difference? In other words can I pick one up at Autozone or do I need
to find a Mercruiser parts dealer?

As far as the rewiring goes, I am going to get started on that too.
My horn doesn't work because of a faulty switch and my tilt/trim has
problems in the up direction. I have to jack around with the switch
to get it to go up, not good. That could be a weak pump I guess but I
would imagine that up and down work on the same pump through a
birdirectional valve. Am I right? I guess it could be a solenoid on
the valve if that is how it works. Any advise on that one?

Back on the impeller, I am pretty good with wrenches and I have a
decent shop and I'm not scared to do it myself. I've heard that I
need to take the outdrive almost completely off to get to the
impeller. Can I get the basic steps from someone who has done this?

Thanks for all of your help. The internet is a wonderful thing.

Chris

Unscrew the (six?) stainless nuts holding the lower unit.
Withdraw it.
Unbolt the pump assembly and disassemble..
Replace the impeller

Check the position of the forward/reverse shaft carefully.
See how the water tube connects the lower to the upper.

Reverse the disassembly instructions
(roughly, from memory...)

Brian W

On 29 Apr 2004 13:34:03 -0700, (Chris) wrote:

Alright, the consensus sounds like I should start with an impeller
replacement. Will do, especially since it sounds like a maintenance
item anyway. If that doesn't work, I'll start looking for other
restrictions in the cooling system. Just to clarify, when I say
overheating, I mean that the temp gauge was pegged and the exhaust
smells of burning oil. The gauge goes up to 240 I believe (I'm not on
the boat right now). When I would rev it and get it to cool down, it
would get down to about 160-180. I have no idea when it was last
replaced so it may have been about dead anyway. I will replace the
thermostat with a new one too instead of putting the old one back in.
It looks just like a standard auto thermostat. Is there any
difference? In other words can I pick one up at Autozone or do I need
to find a Mercruiser parts dealer?

As far as the rewiring goes, I am going to get started on that too.
My horn doesn't work because of a faulty switch and my tilt/trim has
problems in the up direction. I have to jack around with the switch
to get it to go up, not good. That could be a weak pump I guess but I
would imagine that up and down work on the same pump through a
birdirectional valve. Am I right? I guess it could be a solenoid on
the valve if that is how it works. Any advise on that one?

Back on the impeller, I am pretty good with wrenches and I have a
decent shop and I'm not scared to do it myself. I've heard that I
need to take the outdrive almost completely off to get to the
impeller. Can I get the basic steps from someone who has done this?

Thanks for all of your help. The internet is a wonderful thing.

Chris

Unscrew the (six?) stainless nuts holding the lower unit.
Withdraw it.
Unbolt the pump assembly and disassemble..
Replace the impeller

Check the position of the forward/reverse shaft carefully.
See how the water tube connects the lower to the upper.

Reverse the disassembly instructions
(roughly, from memory...)

Brian W

On 29 Apr 2004 13:34:03 -0700, (Chris) wrote:

Alright, the consensus sounds like I should start with an impeller
replacement. Will do, especially since it sounds like a maintenance
item anyway. If that doesn't work, I'll start looking for other
restrictions in the cooling system. Just to clarify, when I say
overheating, I mean that the temp gauge was pegged and the exhaust
smells of burning oil. The gauge goes up to 240 I believe (I'm not on
the boat right now). When I would rev it and get it to cool down, it
would get down to about 160-180. I have no idea when it was last
replaced so it may have been about dead anyway. I will replace the
thermostat with a new one too instead of putting the old one back in.
It looks just like a standard auto thermostat. Is there any
difference? In other words can I pick one up at Autozone or do I need
to find a Mercruiser parts dealer?

As far as the rewiring goes, I am going to get started on that too.
My horn doesn't work because of a faulty switch and my tilt/trim has
problems in the up direction. I have to jack around with the switch
to get it to go up, not good. That could be a weak pump I guess but I
would imagine that up and down work on the same pump through a
birdirectional valve. Am I right? I guess it could be a solenoid on
the valve if that is how it works. Any advise on that one?

Back on the impeller, I am pretty good with wrenches and I have a
decent shop and I'm not scared to do it myself. I've heard that I
need to take the outdrive almost completely off to get to the
impeller. Can I get the basic steps from someone who has done this?

Thanks for all of your help. The internet is a wonderful thing.

Chris

"Chris" wrote in message
om...


Back on the impeller, I am pretty good with wrenches and I have a
decent shop and I'm not scared to do it myself. I've heard that I
need to take the outdrive almost completely off to get to the
impeller.

Nah, not nearly as bad as you make it sound!

The outdrive will have an "upper" and a "lower" section. If the water pump
is in the outdrive at all, it will be at the top of the lower unit.

I say "if" because not all I/O systems have the pump in the outdrive, some
are mounted on the engine. I am not familiar with Mercruiser, but maybe
someone else who is can say for sure.


I have changed a few water pumps on outboards which are similar. The lower
unit usually comes apart at the cavitation plate, four or five bolts that
come up from the bottom (just above the prop). If the outdrive isn't
corroded too badly it should just be a matter of removing the bolts, maybe a
few taps with a rubber mallet.

Once you have the lower unit off the pump should be easily accessible and
obvious. I would expect four bolts holding the cover on. Remove the bolts
to expose the impeller. In a perfect world you would be able to just grab
the impeller with a pair of needle nose and pull it up and out. In the real
world they tend to get stuck on the shaft and you have to work on them some.
In the worse case you have to chisel the hub off the impeller off, which
isn't that hard to do. (at least you can take the lower unit into the
garage!)

Rod

"Chris" wrote in message
om...


Back on the impeller, I am pretty good with wrenches and I have a
decent shop and I'm not scared to do it myself. I've heard that I
need to take the outdrive almost completely off to get to the
impeller.

Nah, not nearly as bad as you make it sound!

The outdrive will have an "upper" and a "lower" section. If the water pump
is in the outdrive at all, it will be at the top of the lower unit.

I say "if" because not all I/O systems have the pump in the outdrive, some
are mounted on the engine. I am not familiar with Mercruiser, but maybe
someone else who is can say for sure.


I have changed a few water pumps on outboards which are similar. The lower
unit usually comes apart at the cavitation plate, four or five bolts that
come up from the bottom (just above the prop). If the outdrive isn't
corroded too badly it should just be a matter of removing the bolts, maybe a
few taps with a rubber mallet.

Once you have the lower unit off the pump should be easily accessible and
obvious. I would expect four bolts holding the cover on. Remove the bolts
to expose the impeller. In a perfect world you would be able to just grab
the impeller with a pair of needle nose and pull it up and out. In the real
world they tend to get stuck on the shaft and you have to work on them some.
In the worse case you have to chisel the hub off the impeller off, which
isn't that hard to do. (at least you can take the lower unit into the
garage!)

Rod

Alright, the consensus sounds like I should start with an impeller
replacement. Will do, especially since it sounds like a maintenance
item anyway. If that doesn't work, I'll start looking for other
restrictions in the cooling system. Just to clarify, when I say
overheating, I mean that the temp gauge was pegged and the exhaust
smells of burning oil. The gauge goes up to 240 I believe (I'm not on
the boat right now). When I would rev it and get it to cool down, it
would get down to about 160-180. I have no idea when it was last
replaced so it may have been about dead anyway. I will replace the
thermostat with a new one too instead of putting the old one back in.
It looks just like a standard auto thermostat. Is there any
difference? In other words can I pick one up at Autozone or do I need
to find a Mercruiser parts dealer?

As far as the rewiring goes, I am going to get started on that too.
My horn doesn't work because of a faulty switch and my tilt/trim has
problems in the up direction. I have to jack around with the switch
to get it to go up, not good. That could be a weak pump I guess but I
would imagine that up and down work on the same pump through a
birdirectional valve. Am I right? I guess it could be a solenoid on
the valve if that is how it works. Any advise on that one?

Back on the impeller, I am pretty good with wrenches and I have a
decent shop and I'm not scared to do it myself. I've heard that I
need to take the outdrive almost completely off to get to the
impeller. Can I get the basic steps from someone who has done this?

Thanks for all of your help. The internet is a wonderful thing.

Chris

"Chris" wrote in message
om...
OK, I am a new boat owner and am learning the hard way. I am pretty
sure that I have fried the water impeller in the stern drive. I have
an '81 Glastron SX-190 with a Mercruiser 228hp 305. I didn't know,
until now, that the boat should never be started even for a few
seconds without water supply at the stern drive.

Yep, true, never ever run the engine without a flow of water!

Of course, this is a "do as I say, not as I do" thing. I always hit the
starter before I get to the ramp just to make sure that the boat will start
when I get it to the water. Crank, Start, shut off! Not a good idea, but I
do it anyway. I get three or four years out on a water pump impeller.

Your boat is an '81. Any idea when the impeller was changed last? How many
hours it has on it?

It was possible, indeed likely that the impeller was on its last legs when
you bought the boat. There are two approaches to changing your impeller:
one is wait until it fails, the other is preventative.

On my ski boat, I can change the impeller with only a screw driver in about
10 minutes with the boat in the water. I carry a spare impeller at all
times, just in case (I have also sucked up weeds that chocked off the water
supply and caused the impeller to burn out). For me, running it until it
fails is not a big deal.

Not sure about Mercruisers, but some I/Os and all outboards the water pump
is in the lower unit. You don't want to be changing the impeller with the
boat in the water. Having the impeller fail can ruin your day, weekend or
even life if you happen to be off shore when the water pump fails and you
can't fix it. In such a case, changing the water pump impeller every year
or two is a good idea.

Rod