Engine performance

[peterboater54]

I recently bought a 2007 232 Gulfstream with twin Yamaha 150 4 strokes. Have been running them at different RPM's to see how they perform. On several occasions one or both engines have shut down due to overheating. I know this can happen with 4 stroke engines if you run them wide open for too long. But that is nit the case. I have experienced this overheating while cruising at 4400 RPM's. Any suggestions/explanations would be most helpful.

Thanks,

PeterBoater54

 

[SmokyMtnGrady]

I had a F150 on my 192 and sold it with about 700 hours on it. I was religious about changing the water pump at 100 hours. When we would run to Silver Glenn springs on the mighty St. Johns sometimes that filamentous green algae and jungle val would clog the intake ports and the overhear alarm would sound. We would stop and clean them. Do you know when the water pumps have been last replaced?

 

[ElyseM]

I know this can happen with 4 stroke engines if you run them wide open for too long.

never heard of that, but i'm not an authority. i had a 232 w/ twin f200's. picked up a plastic bag on one engine once and got the alarm but it did not shut down. i shut it and cleared the bag.

are you sure it's not a fuel issue? are you getting alarms? maybe one of the yammie experts can chime in with how long an alarm will sound before "auto shutdown" occurs.

as smg said, could be water quality, but i'm surprised that it just shuts down like that. ron

 

[Bill_N]

Thermostats?

 

[Grog]

... or water pumps or poppets.

No engine should overheat at full throttle or any other throttle for that matter.

 

[peterboater54]

Thanks for the replies folks. Re-reading my note I see that I mis-spoke: The engines don't actually shut down. What happens is the alarm(s) sound, I pull back on the throttles. The alarm will not shut off unless I shut down the engines, but I have to admit I do not wait that long as the alarm is annoying. I have not changed the water pump, but the engines were serviced at 200 hours by Yammie certified mechanic. I will watch for the seaweed at the intake. I will check on the thermostats as well. Grog, why do you say that no engine should overheat at full throttle? I thought that was most likely with 4 strokes, not at all likely with 2 strokes.

Thanks again. You folks are great.

Peter

 

[Grog]

The outboards were designed to run through their operating range. If seaweed clogs the entrance, you will overheat but normally there is plenty of water being pumped to the block to cool it.

 

[lgusto]

The notion that normal operation, anywhere from idle to WOT, will cause an engine to overheat is nonsense. Modern 4 strokes are engineered to be bullet proof and immune to anything we can throw at them within reason. If you're getting an overheating shutdown something's wrong with the sensors or the engines themselves. It is possible that you're running through some sort of high intensity weed line or algae concentration but that seems unlikely on a regular basis. Just my two cents.