Excessive Exhaust Steam? or does this look normal?

Hello all. It's been a number of years since I last posted here (which has translated to many years of happy boating) but now I could use some opinions.

I have a 1998 Yamaha P150 TRLX 2-stroke outboard on my 89 Deckboat.

Out on the water a few weeks ago I had a warning buzzer go off - normally it's the oil tanks (because the sensors don't work/transfer correctly - long story) but this time it looked normal and the buzzer continued to sound even with the motor off. I let it sit for a few hours and the buzzer went away and never came back on the rest of the evening.

I had just replaced the water pump impeller + seals, and the pee'er stream was extremely strong and the water temp was maybe luke-warm at best? Still, during that outing it looked like there was a bit of steam at the back of the motor even though the exhaust water stream looked and felt normal. (unfortunately I forgot to take note of what particular warning the gauge was flashing during the buzzing)

I went ahead and and changed the thermostats tonight - it'd been a few years and the old ones looked pretty crusty.

I also noticed the remote oil tank was a bit low (maybe down about 1/4 tank?) so I added a few quarts there as well just on the offchance the buzzer was due to this tank being low - i.e. the hull tipped back enough on power that the sensor dropped really low.

I hooked the motor up to the hose tonight, flushed everything out, then fired it up and let it run 5-10 minutes to get up to temperature, revved it a few times and never got the buzzer to sound.

Ordinarily I'd call that a win, but I noticed more steam than what I'm accustomed to coming out of the exhaust around the prop, and the force of the exhaust + water was strong enough to actually spin the prop. I can't recall ever seeing that before so I wanted another set of opinions before I start to worry. (As a note, out of the water the engine idles at 1200-1300 rpm.)

THE ONLY REASON I'm being so paranoid is because the garage I store the boat in over the winter got down below freezing during a couple of points (broken heater) and remembering this, I briefly got cold-sweats thinking that some moisture froze up inside of there and possibly really hurt something.

I'm linking a picture of what it looked like with the engine running, at idle, and at temperature. Does this look concerning or am I just being paranoid? Thanks in advance.

(forum wouldn't let me attach, sorry!)

if the stat was crusty looking ,I am sure all the passages are too.
Rydlime Marine descaler pumped thru does a good job of cleaning it out.

Crusty does break off in chunks sometimes. Being a erratic alarm might just be chunks or that unreliable old oil system.

while the motor is running can you hold your hand up, or a piece of paper, in front of the smoke/steam? maybe that way you can tell if it's steam or oil burning.

99yam40 said:

if the stat was crusty looking ,I am sure all the passages are too.
Rydlime Marine descaler pumped thru does a good job of cleaning it out.

Click to expand...

I've never used that stuff before, but that's a great suggestion. I'll look up how to use it. (I've never had any luck with muffs on my motor - I only use the hose hookup/flusher.)

I took the boat out on the water yesterday afternoon and it seemed to have settled down (no alarms,) but I never had a chance to really jump on it or get on plane.

I drop the lower unit off, hooked a hose up to the pipe heading up to the power head.
hook that hose to a pump sitting in a tub or bucket with the solution in it, pulled the stat out to allow the solution to flow freely thru the motor and turn on the pump.
make sure the tell-tale is routed down into the bucket and catch all of the solution to keep recycling.
I have heated the water I used to dilute the Rydlime before to make it more reactive, but the instructions do not mention heating anything.
some say to remove any anodes you can before doing this.
I am not sure how bad it is on the anodes

I have just ordered 20 litres of hi strength vinegar with the intention of flushing out my Honda . 1st time so I will let you know how it goes .