I have a 27' Starwind with a 13hp Phasor (Beta Marine
Clone) 2 cylinder. I hadn't run the motor
in a month or so, but the last time we were out, it was running and cooling
When I fired her up Sunday morning, it was flowing water
out the exhaust
, but it didn't seem quite up to what I was used to seeing. It was maybe half the usual flow, but it was still cooling
at idle without a problem.
Once we put the boat in gear
and revved it up, I started getting mostly steam out of the exhaust
, and our temperature started rising. If I ran down at 1500rpm, it would flow enough water
to cool the boat back down, so we creeped back in to the dock
The raw water
system is set up like this: through-hull > strainer > pump > heat exchanger
> vented loop > mixing elbow
> out the exhaust.
First thing we did was check the strainer. There were some remnants of sea life in the basket, but not enough of anything that it would have stopped water flow.
I then pulled the hose off the pump and blew back through the strainer. I could blow through with no problem, so the through-hull was not restricted.
I pulled the cover off the raw water pump
. The impeller, which is less than a year old, still looks new.
I pulled the mixing elbow
. It has some carbon build-up inside it, but not enough that it should have restricted exhaust pressure or caused excessive heat pockets. I cleaned it out and put everything back together.
None of this helped. I'm still getting half water flow at idle, and flow goes down and steam increases as a throttle up.
The heat exchanger
was too hot to drain and take apart, so I'm going to pull the tubes out of it next weekend to check them, but it's been less than a year since I serviced them.
What am I missing? Aside from a potentially clogged heat exchanger is there anything else I should check? Why does water flow decline with RPMs?