Volvo AQ130C "warm up" cooling issue

[am_dew]

After I start my AQ130C (raw water cooled) after launching, while the engine is warming up I have to keep a very close eye on the water temp. gauge for a while to be sure that the water pump is pushing water thru the engine. If I notice that the water temp is rising higher than normal, I give the engine a few quick revs and the water temp then starts to drop. I run the engine during "warm up" at about 1000 RPM. I recplaced the water pump impeller about a month ago and checked it a few outings later to find it in good shape. The water pump is fairly new...3-4 years old. Once the water pump is pushing water thru the engine, everything is fine after that and the engine runs like a champ with no overheating issues for the rest of the day and although I always keep a close eye on the temp gauge anyway, ths "warm up" issue does not repeat itself when restarting after a stop (ie. after shoring the boat and taking a lunch break). I'm wondering if I should increase the "warm up" RPMS to about 1500 to see if that helps get water circulating right away? Any other ideas or suggestions? Thanks.

 

[am_dew]

Re: Volvo AQ130C

Re: Volvo AQ130C

It also occurred to me just now that perhaps the water pump is working fine but my t-stat is not opening when this happens. But I don't know how revving the engine will cause the t-stat to suddenly open.

 

[Don S]

Re: Volvo AQ130C

Re: Volvo AQ130C

You've probably got an air leak on the intake side of your raw water pump. Possible the seal on the pump shaft or the gasket for the impeller cover.
Or a hose connection leaking.