I have a 350 with an Alpha 1 that is overheating at low rpms. Diagnosing
the same problem last year, I had to have the water pump in the lower unit
replaced. I will troubleshoot all other possibilities this weekend before
having to pull the boat out, but thought you folks in the news groups may
have some ideas as to what other causes it could be.

The boat is an 86 and I have owned it for about ten years for having to
replace the outdrive water pump. Any estimates as to what the life
expectancy of the water pump should be?

First I will be checking for leaks, then changing the t'stat on the engine
(as I do not recall when I last replaced it), but beyond that, Ican only
suspect either the new (last year) pump has failed prematurely, or the
mechanic I hired to do it did.

Mark (the rail & canopy hook guy)
www.ripnet.com/vtf/prod03.htm

On Fri, 3 Jun 2005 07:37:16 -0400, "Mark" wrote:

I have a 350 with an Alpha 1 that is overheating at low rpms. Diagnosing
the same problem last year, I had to have the water pump in the lower unit
replaced. I will troubleshoot all other possibilities this weekend before
having to pull the boat out, but thought you folks in the news groups may
have some ideas as to what other causes it could be.

The boat is an 86 and I have owned it for about ten years for having to
replace the outdrive water pump. Any estimates as to what the life
expectancy of the water pump should be?

First I will be checking for leaks, then changing the t'stat on the engine
(as I do not recall when I last replaced it), but beyond that, Ican only
suspect either the new (last year) pump has failed prematurely, or the
mechanic I hired to do it did.

Mark (the rail & canopy hook guy)
www.ripnet.com/vtf/prod03.htm


Have you checked the circulating pump on the engine? Mine conked out after about
six seasons.

--
John H
On the 'PocoLoco' out of Deale, MD

"Divide each difficulty into as many parts as is feasible and necessary to resolve it."
Rene Descartes (A true binary thinker!)

Good thinking John! I had almost forgotten about the engine mounted pump.
Short of removing it and checking the impeller, if you or anyone has an
suggestions how I could test itwithout removing, it would be much
appreciated.

Mark (the rail & canopy hook guy)
www.ripnet.com/vtf/prod03.htm

"John H" wrote in message
...
On Fri, 3 Jun 2005 07:37:16 -0400, "Mark" wrote:

I have a 350 with an Alpha 1 that is overheating at low rpms. Diagnosing
the same problem last year, I had to have the water pump in the lower unit
replaced. I will troubleshoot all other possibilities this weekend
before
having to pull the boat out, but thought you folks in the news groups may
have some ideas as to what other causes it could be.

The boat is an 86 and I have owned it for about ten years for having to
replace the outdrive water pump. Any estimates as to what the life
expectancy of the water pump should be?

First I will be checking for leaks, then changing the t'stat on the engine
(as I do not recall when I last replaced it), but beyond that, Ican only
suspect either the new (last year) pump has failed prematurely, or the
mechanic I hired to do it did.

Mark (the rail & canopy hook guy)
www.ripnet.com/vtf/prod03.htm


Have you checked the circulating pump on the engine? Mine conked out after
about
six seasons.

--
John H
On the 'PocoLoco' out of Deale, MD

"Divide each difficulty into as many parts as is feasible and necessary to
resolve it."
Rene Descartes (A true binary thinker!)

On Fri, 3 Jun 2005 08:50:55 -0400, "Mark" wrote:

Good thinking John! I had almost forgotten about the engine mounted pump.
Short of removing it and checking the impeller, if you or anyone has an
suggestions how I could test itwithout removing, it would be much
appreciated.

Mark (the rail & canopy hook guy)
www.ripnet.com/vtf/prod03.htm

"John H" wrote in message
.. .
On Fri, 3 Jun 2005 07:37:16 -0400, "Mark" wrote:

I have a 350 with an Alpha 1 that is overheating at low rpms. Diagnosing
the same problem last year, I had to have the water pump in the lower unit
replaced. I will troubleshoot all other possibilities this weekend
before
having to pull the boat out, but thought you folks in the news groups may
have some ideas as to what other causes it could be.

The boat is an 86 and I have owned it for about ten years for having to
replace the outdrive water pump. Any estimates as to what the life
expectancy of the water pump should be?

First I will be checking for leaks, then changing the t'stat on the engine
(as I do not recall when I last replaced it), but beyond that, Ican only
suspect either the new (last year) pump has failed prematurely, or the
mechanic I hired to do it did.

Mark (the rail & canopy hook guy)
www.ripnet.com/vtf/prod03.htm


Have you checked the circulating pump on the engine? Mine conked out after
about
six seasons.

I realized I had problems with it when I noticed a rust trail coming from the
bottom. There is a seep hole that will leak when the seals in the pump go bad.

--
John H
On the 'PocoLoco' out of Deale, MD

"Divide each difficulty into as many parts as is feasible and necessary to resolve it."
Rene Descartes (A true binary thinker!)

Sorry I don't have the reference, but 3 years or so is the "recommended"
impeller replacement schedule. And that I think is based on a 100 hours or
so season. I also understand that the newer impellers are built to last
longer. My approach ... pull the outdrive every 3 seasons to lube the
u-joints etc, and while it's off replace the impeller. And then there are
people run their boats 10 years with no preventive maintenance and have no
problems :-)

"Mark" wrote in message
sgroups.com...
I have a 350 with an Alpha 1 that is overheating at low rpms. Diagnosing
the same problem last year, I had to have the water pump in the lower unit
replaced. I will troubleshoot all other possibilities this weekend
before
having to pull the boat out, but thought you folks in the news groups may
have some ideas as to what other causes it could be.

The boat is an 86 and I have owned it for about ten years for having to
replace the outdrive water pump. Any estimates as to what the life
expectancy of the water pump should be?

First I will be checking for leaks, then changing the t'stat on the engine
(as I do not recall when I last replaced it), but beyond that, Ican only
suspect either the new (last year) pump has failed prematurely, or the
mechanic I hired to do it did.

Mark (the rail & canopy hook guy)
www.ripnet.com/vtf/prod03.htm

Oops ... I read "water pump" as the engine water pump, not impeller. If it
was me, I'd pull the boat out and hook up the muffs and garden hose. Could
be someone started the engine up with no water supply ... that burns out the
impeller. Or could be the engine water pump, or risers blocked, or
thermostat, or .... could even be a faulty temperature gauge. Anyway,
running it on the garden hose should give some insight into the problem.

Agreed on the engine pump, this is the most typical cause of low RPM over
heating and OK at higher. It isn't a displacement pump like the one on the
drive, it is a centrifugal pump and as it ages, the vanes corrode off, they
simply don't sling any water at low speeds then. End result is lots of
water from driver pump, however it isn't circulated through the block, it
just get poured out the exhaust. The engine pump is responsible to move it
through the block and heads.

Common issue on cars with high mileage also, overheat at idle, OK if revved
up a bit..

Greg

"Bowgus" wrote in message
...
Oops ... I read "water pump" as the engine water pump, not impeller. If
it
was me, I'd pull the boat out and hook up the muffs and garden hose. Could
be someone started the engine up with no water supply ... that burns out
the
impeller. Or could be the engine water pump, or risers blocked, or
thermostat, or .... could even be a faulty temperature gauge. Anyway,
running it on the garden hose should give some insight into the problem.

There is more to go wrong than just the pumps.

I'm going through my own over heating issues at the moment with a Volvo 240A
(Ford 351W, w/ freshwater cooling).

I just ran three days in a row. First day was fine, but I noticed a slightly
higher temp, but still cooler than most guys run.

Second day, I forgot to check the water level, and during a brief downtime
on the water, it bugged me enought that I opened it up and added about 2
litires of water to the system. A couple of hours after that, I noticed the
temp. going higher any time I got it up on plane. Trolling speed was fine so
we fished home and picked up a fish that I would not normally have got.

Back at the dock, I pulled the thermostat and topped up the water. At the
dock it ran ice cold and never budged the needle on the guage. Next morning
I was able to run about 20 minutes and had to cool it down and add water. I
made it out, stopping about a half dozen times to add water. I ran with the
engine cover off and noticed that as soon as the temp got above about 170F
it started to leak out the overflow at the cap. I was able to troll all day
and never broke 140F. We picked up six salmon up to 20 pounds.

I am suspecting that my problem is in the fresh water side. The heat
exchanger is ice cold on one end and the risers are cool enought to hold
your hands on for as long as you want (and I'm sensitive to heat!). I think
that I may have something clogging the heat exchanger. I'll pull it off next
week and get it boiled out, along with the manifolds and risers. (though
last year they were pretty clean inside.


"Mark" wrote in message
sgroups.com...
Good thinking John! I had almost forgotten about the engine mounted
pump.
Short of removing it and checking the impeller, if you or anyone has an
suggestions how I could test itwithout removing, it would be much
appreciated.

Mark (the rail & canopy hook guy)
www.ripnet.com/vtf/prod03.htm

"John H" wrote in message
...
On Fri, 3 Jun 2005 07:37:16 -0400, "Mark" wrote:

I have a 350 with an Alpha 1 that is overheating at low rpms.
Diagnosing
the same problem last year, I had to have the water pump in the lower
unit
replaced. I will troubleshoot all other possibilities this weekend
before
having to pull the boat out, but thought you folks in the news groups
may
have some ideas as to what other causes it could be.

The boat is an 86 and I have owned it for about ten years for having to
replace the outdrive water pump. Any estimates as to what the life
expectancy of the water pump should be?

First I will be checking for leaks, then changing the t'stat on the
engine
(as I do not recall when I last replaced it), but beyond that, Ican only
suspect either the new (last year) pump has failed prematurely, or the
mechanic I hired to do it did.

Mark (the rail & canopy hook guy)
www.ripnet.com/vtf/prod03.htm


Have you checked the circulating pump on the engine? Mine conked out
after
about
six seasons.

--
John H
On the 'PocoLoco' out of Deale, MD

"Divide each difficulty into as many parts as is feasible and necessary
to
resolve it."
Rene Descartes (A true binary thinker!)

Unbolt the end cap on the heat exchanger. I have had pebbles in mine. But
I run a jet drive and the freshwater comes off the jet.

"Jim Pook" wrote in message
...
There is more to go wrong than just the pumps.

I'm going through my own over heating issues at the moment with a Volvo
240A
(Ford 351W, w/ freshwater cooling).

I just ran three days in a row. First day was fine, but I noticed a
slightly
higher temp, but still cooler than most guys run.

Second day, I forgot to check the water level, and during a brief downtime
on the water, it bugged me enought that I opened it up and added about 2
litires of water to the system. A couple of hours after that, I noticed
the
temp. going higher any time I got it up on plane. Trolling speed was fine
so
we fished home and picked up a fish that I would not normally have got.

Back at the dock, I pulled the thermostat and topped up the water. At the
dock it ran ice cold and never budged the needle on the guage. Next
morning
I was able to run about 20 minutes and had to cool it down and add water.
I
made it out, stopping about a half dozen times to add water. I ran with
the
engine cover off and noticed that as soon as the temp got above about 170F
it started to leak out the overflow at the cap. I was able to troll all
day
and never broke 140F. We picked up six salmon up to 20 pounds.

I am suspecting that my problem is in the fresh water side. The heat
exchanger is ice cold on one end and the risers are cool enought to hold
your hands on for as long as you want (and I'm sensitive to heat!). I
think
that I may have something clogging the heat exchanger. I'll pull it off
next
week and get it boiled out, along with the manifolds and risers. (though
last year they were pretty clean inside.


"Mark" wrote in message
sgroups.com...
Good thinking John! I had almost forgotten about the engine mounted
pump.
Short of removing it and checking the impeller, if you or anyone has an
suggestions how I could test itwithout removing, it would be much
appreciated.

Mark (the rail & canopy hook guy)
www.ripnet.com/vtf/prod03.htm

"John H" wrote in message
...
On Fri, 3 Jun 2005 07:37:16 -0400, "Mark"
wrote:

I have a 350 with an Alpha 1 that is overheating at low rpms.
Diagnosing
the same problem last year, I had to have the water pump in the lower
unit
replaced. I will troubleshoot all other possibilities this weekend
before
having to pull the boat out, but thought you folks in the news groups
may
have some ideas as to what other causes it could be.

The boat is an 86 and I have owned it for about ten years for having to
replace the outdrive water pump. Any estimates as to what the life
expectancy of the water pump should be?

First I will be checking for leaks, then changing the t'stat on the
engine
(as I do not recall when I last replaced it), but beyond that, Ican
only
suspect either the new (last year) pump has failed prematurely, or the
mechanic I hired to do it did.

Mark (the rail & canopy hook guy)
www.ripnet.com/vtf/prod03.htm


Have you checked the circulating pump on the engine? Mine conked out
after
about
six seasons.

--
John H
On the 'PocoLoco' out of Deale, MD

"Divide each difficulty into as many parts as is feasible and necessary
to
resolve it."
Rene Descartes (A true binary thinker!)

You don't say whether you operate in fresh or salt water, or whether your
engine has fresh water w/anti-freeze circulating coolant (w/ heat
exchanger). Esp if it's operated in salt water, on a '86 boat, I'd bet on
the riser being clogged. Pull it and have a look -- you'll need new gaskets
when making replacement. You can "rod it out" or have a radiator shop give
it an acid cleaning -- either will give you just one or two seasons more.
Usually better to buy new if you intend to keep the boat.

First choice would have been lower unit pump impeller, but that's fairly
new -- unless it was later run dry and damaged. Impellers should be changed
every three years or so for normal recreational boats. The rubber gets stiff
with age and they lose efficiency. In water with lots of silt and
particulates, esp frequent shallow water operation, they can wear out faster
due to abrasion. Same for the metal contact surface in the pump --
inspection will tell if that (or more likely) the whole pump needs replaced.

Good luck,
Len

Eliminate "ns" for email address.

--
"Mark" wrote in message
sgroups.com...
I have a 350 with an Alpha 1 that is overheating at low rpms. Diagnosing
the same problem last year, I had to have the water pump in the lower unit
replaced. I will troubleshoot all other possibilities this weekend
before
having to pull the boat out, but thought you folks in the news groups may
have some ideas as to what other causes it could be.

The boat is an 86 and I have owned it for about ten years for having to
replace the outdrive water pump. Any estimates as to what the life
expectancy of the water pump should be?

First I will be checking for leaks, then changing the t'stat on the engine
(as I do not recall when I last replaced it), but beyond that, Ican only
suspect either the new (last year) pump has failed prematurely, or the
mechanic I hired to do it did.

Mark (the rail & canopy hook guy)
www.ripnet.com/vtf/prod03.htm