Thread: Running Cold
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Old 06-15-2009, 09:17 PM
Tom Graham Tom Graham is offline
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Quote:
Originally Posted by Don Moyer View Post
Tom,

Your situation is very perplexing. We usually say that "overcooling" can only be caused by water flowing through a partially stuck open thermostat, flowing around a closed thermostat if the head and/or base of the housing is corroded or the gauge is defective. I would also add that if there is any unusual restriction in the bypass loop, it can sometimes force water through even a normal thermostat and housing.

We really have no history to suggest that an M7 cam shoe leads to overcooling.

All that being said, it will be interesting to follow your case history to learn what is causing the overcooling.

Don
The boat has been in the water for a little over a month. As soon as it was launched I realized that there were problems with a leaky exhaust system so I had to replace that. I bought the Moyer flange and pressure gauge kit. The new system works well and back pressure seems to be low at less than one PSI.

From the first short run after launching (before I replaced the exhaust between the engine and the water lift muffler including the water injection fitting) the temperature was showing signs of much improvement. The temperature quickly rises to about 140, the opening point of the thermo (which I tested before installing).

This weekend after running at max speed, probably about 1700 RPM for an hour or so in calm weather, the temperature soon stabilized at about 160. Lake Champlain is still probably at about 60 degrees so that is not too bad. Everything seems normal.

What did I do?

Two things relating to this issue. I also in addition to the exhaust repair, did the points and reset the timing but the temperature problem would not be affected by this. The points were not that bad and the previous timing was correctly set.

The two things were:

#1

I bought the new Moyer pump and installed it along with new hose. none of the old stuff was blocked just upgrading to the proper Marine grade. Remember I said I had installed a new impeller in the old pump with the M7 cam shoe supplied with the new impeller.

#2

I reinstalled (after checking as menitioned above) the old 3 spring thermostat.

Verdict!

The old pump had more pressure causing the water to prematurely force open the thermostat or if the new pump has the same pressure then the 3 spring thermostat provides just the extra seating force needed to prevent being forced open before the rated temperature is attained.

Your comments would be appreciated.

Tom G.
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