Running Cold

[domagami]

Cold running

Yes, I would have preferred to have taken the scientific approach, but as you say, I just need it fixed. When you're looking at taking a 41-year-old boat through downtown Chicago on a Saturday morning and the city stops traffic at 22 different bridges and one lock for you.... you better be ready to go and keep going for five hours straight. Stopping for a fix is not an option.

We'll never know for sure, but I think the issue was the timing. After setting the points I then (for the first time) did the adjustment with the distributor mount.

I would have to go look at my references - and maybe here Don or someone else could clarify it for other readers interested in this issue - but I think if you're running on the cool side AND you have dry & sooty plugs then you're probably looking at a timing issue. Don't rely on my word for it, but later postings might clarify that. (And yes, that's what my plugs looked like)

Good luck to all, hope this helps someone else in some way.

[marthur]

It was a combination of engine timing and mixture that caused my engine to run cool.

In a seperate and unrelated incident, I also had a piece of waterpump impeller from the previous owner work its way through the system. That caused the engine to run COLD, not just cool. Cold enough that the temp gauge did not even register a reading. The piece of impeller was blasted loose when I rebuilt the water pump, due to the higher water pressure created by the new pump.

[Tom Graham]

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.

[Jamaral]

Running cold

I have owned my Columbia with an atomic 4 for 3 seasons in the north east. The temp is always at 120... I can raise the temp by reduceing the sea water entering the pump. Once the motor starts I push the choke all the way in but until recently it has never stalled. Now it stalls until it runs for a few minutes. .. once the motor warms up it dosnt Stall. Not sure if I should be alarmed with this or if it is a trait of an atomic4. Should I keep it chocked for a while and is it ok to run at 120 if I don't. Have any issues