Sorry about omitting important data. I was hot and itchy from fiber glass work
earlier in the morning.
Anyway, here is the info.
fixed prop, 18" dia (pitch unknown)
, 5444 (44 hp)
is 17,000lbs, but might be irrelevant because engine tests were done at dock
Max throttle 3100rpm
Fresh and raw water
systems recently cleaned and all hoses changed
Fresh water pump
not changed, age unknown
Raw water impeller fairly new, not much use, still flexible and intact
In neutral,I did get 3000 rpm WOT
Only got up to 2200 rpm WOT in fwd
Didn't test reverse
The temp gauge had the following temp pattern over time
Rose from 0 to about 150 over 10 minutes, then dripped quickly to about 120 over about 90 seconds. ( I guess thermostat opened)
then temp rose steadily to about 165, where is stayed for about 20 minutes while rpm stayed around 2000
I then increased throttle and noticed that rpm rose slowly as I increased throttle and max throttle resulted in 2200 rpm (not normal)
During whole time, saw normal amount of raw water exiting the exhaust thru hull
The engine and prop rotation sounded different from normal, much lower tones and engine didn't react as quickly to throttle increases, somewhat delayed, slow reaction. No hesitation, just slow.
The boat is tied up at the dock
, never left dock
I noticed that the prop wash was not as violent as usual and the lines didn't seem as stressed as they usually are when I exercise engine at the dock. There was also not as much turbidity in prop wash. I thought maybe because water was higher than when I last ran engine.
There was noticeable wobbling feeling and noise
when rpm was over about 1800, increased as rpm increased.
I suspected that, at the very least, barnacles had the prop out-of-balance, so I shut it down and hopped in the water to clean barnacles off. There were a lot of them.
In December, I hauled boat, cleaned and painted the bottom, as well as cleaned shaft/strut/prop down to metal, so it was all good and clean back then.
It was amazing to see how thick and large the barnacles were in just 7 months. Barnacles appear to prefer bronze
over SS because, although the strut and prop were completely covered with barnacles, the shaft had mostly bare metal with a few, large barnacles, maybe 30% covered.
Anyway, once I cleaned barnacles off prop and shaft, I restarted the engine and noticed that it was much better. It reved up to 3000 WOT in forward and in neutral, the wobbling was gone and and the engine noise
no longer had that lower-pitched noise that I had heard when barnacles covered the prop. Prop wash was much more pronounced with really cloudy prop wash this time.
Dock lines were much tighter this time around also.
I had thought I might have an air pocket in the freshwater coolant
, and have not ruled that out yet, but it seems that the barnacles did have a large effect on the engine/prop performance.
If you think of any thing else to check, I'd like to get it running smoothly and eliminate any doubt I have in its reliability
, especially with peak hurricane
probability next month.
I heard that reving the engine might chase air pockets out of the fresh water coolant lines, any truth to that?
Paul, thanks for your help, i can't think of any more info to enter and I hope it was just a case of high barnacle density.