Mercruiser 260 with half-closed cooling system (cooled manifolds but not the risers). Running an SE106 outdrive (sea-water pump) with standard engine circulating water pump on the block.
185 degree t-stat, which I think I need to reduce to a 165. Either way, the motor takes a while to warm and when it does it will slowly climb to the tstat temp. Once there, it will drop suddenly to about 140, then slowly creep back up - hold and drop again. This will happen for a over an hour of run time at about 3000 rpm until the engine is really warm, at which time it will hold for a while (20 mins or more) at about 185-190 - the temp of the tstat....
Once I idle down, the temp will often drop fast again to 140, then slowly build back up
It acts like the tstat is snapping open and letting in a rush of cool water, which drops the temp quickly, then ...
My question is, Too Quickly? Bad guage? Is this normal? Seems like it ought to hit the t-stat temp and hang out there with only mild fluctuations, if any.
As always, thanks for the help...
185 degree t-stat, which I think I need to reduce to a 165. Either way, the motor takes a while to warm and when it does it will slowly climb to the tstat temp. Once there, it will drop suddenly to about 140, then slowly creep back up - hold and drop again. This will happen for a over an hour of run time at about 3000 rpm until the engine is really warm, at which time it will hold for a while (20 mins or more) at about 185-190 - the temp of the tstat....
Once I idle down, the temp will often drop fast again to 140, then slowly build back up
It acts like the tstat is snapping open and letting in a rush of cool water, which drops the temp quickly, then ...
My question is, Too Quickly? Bad guage? Is this normal? Seems like it ought to hit the t-stat temp and hang out there with only mild fluctuations, if any.
As always, thanks for the help...
