I recently discovered something others may not have and would find helpful. After several days of skiing, our VP AQ125A started showing temp increases regardless of rpm & load -- came up to about 200-210 - which has never happened in the 25 years we've had the boat. The engine normally comes up to 180 and pretty much stays there, with minor increase / lower as thermostat closes/opens (190) Upon inspection of the circulating coolant in the expansion tank, it did not appear particularly low, but it was below both the small holes on the side of the filler tube so I started adding water. Surprisingly, as I added water, it disappeared into the top hole and in all took the better part of a quart to fill to between holes (which are very close, one above the other). After doing this, the engine returned to running at 180 the rest of the week - no more heating issues. A "pro" will probably say, "well, duh" to this, but it seemed like such a minor amount of add to the coolant to have such a dramatic effect that I thought others might also miss it and find this helpful.
