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!)