I'm overjoyed I coaxed you into a proper reply to Bart's Question Jeff! ;-P

Seriously... each step you illustrated was correct... and I don't have a
gauge so I have to assume a warning buzzer. I've had a few clogged intakes
in time and a couple of bad impellers.... I concur with your assessment of
Yanmar Pumps!

CM


"Jeff Morris" wrote in message
...
| The coolant flow can be checked by inspection almost immediately, though a
| partial clog can look OK and still send it into Overheat. Certainly I'd
look
| there first if there was any significant change.
|
| However, if the gauge is moving quickly, like up and down in a matter of
| seconds, it can't be a real temperature issue, because the coolant can't
change
| temperature that quickly. I've never had a temp sensor do that, but I've
seen
| it from a faulty oil pressure sensor, and I've seen it from a dangling
wire.
|
| When my heat exchanger was partially clogged the engine was more sensitive
the
| overheating problems. I could tell within a few seconds if my wife turned
on
| the microwave because the temp would start to creep up. Now the temp is
a bit
| more stable, but I can't run the engine up to 3000 rpm if the alternator
is
| fully loaded.
|
| BTW, last week I did have an overheat situation: within a minute after
dropping
| the mooring at Kittery, I noticed the starboard engine temp going up. It
put it
| into neutral and asked my wife to check the water flow - there was none.
We
| killed the engine and went back to the mooring (its sometimes nice to have
two
| engines!). First I pulled the intake of the pump - full flow meaning no
intake
| clog. Then I pulled the output hose off and asked my wife to "start" with
the
| kill switch pulled - no flow. At that point I just pulled off the water
pump,
| removed the cover (damn Yanmar mounted the pump on the GM's so that the
cover
| can't be reached without pulling the pump!). The impellor looked OK, but
my
| wife asked how it worked so I spun the pulley to show her but the impeller
| didn't spin! I seems the impellor was spinning free on its hub. A spare
was
| put in and we were underway again with a total delay of about 45 minutes.
|
|
|
|
| "Capt. Mooron" wrote in message
| ...
| Good Grief Jeff...... if you have a coolant problem you'd check the
belts???
| Wouldn't you tend to believe the sensor and simply verify the coolant
flow
| prior to questioning your instruments?
|
| CM
|
| "Jeff Morris" wrote in message
| ...
| | Oh! The ENGINE temperature!
| |
| | Even if there is a cooling problem, the engine provides a significant
| buffer, so
| | if the fluctuation is fast, as in you actually see the needle move,
its
| probably
| | a loose connection on the sensor, or some other such fault.
| |
| | If its a small engine with a large alternator it could be a slipping
belt.
| I've
| | never seen a case where the coolant flow went up and down repeatedly
but I
| | suppose it could happen. Can a thermostat fail in this mode?
|
|
|
|