Telltale water is really hot after idle

[Scout3a]

This may be a weird one but, I have twin 2014 F250’s on my 265 Express. I recently dropped the boat in the water but the weather has been crappy so I haven’t been out yet. I went down to my boat to clean and let the engines run for a little while to make sure everything is set so when the weather turns I’m GTG.

I ran my engines for around 10 minutes then decided to flush them like I always do. When I unscrewed the flush line I noticed the water coming back out of the engine was really hot? Has anyone ever experienced this and is this something that I I can correct on my own?

 

[seasick]

What was the temp of the water?
I don't think anything is wrong. The engine was warmed up and as soon as you stopped the motor, the water that is still in the powerhead will get hotter due to the latent heat of the engine.
You should test the temp of the telltale stream when the motor is running. If it was cool outside, the water will feel hotter than it actually is.
As long as you see a good telltale when running and you don't get an overheat alarms, I think your are fine.

 

[magicalbill]

I agree with Seasick. I always flush my V8 350's with the engine running at idle and have noticed several times the water coming out is hot. Same with my V6 F200's on my previous Gulfstream.

Never have I had any overheat alarms on either the V8's or the V6's.

 

[Hookup1]

Never checked mine. Was the water hot on both engines?

If you have you're engines interfaced with the chartplotter like my Garmin/Yamaha F150's you will have a temperature gauge for both engines.

You weren't getting an alarm so that's good. Are your alarm's working? Turn key to "ON" - alarm beeps? Check other engine.

Put a thermometer on the output of the telltale. Do they both match? How is the water flow? It's possible that the flow thru the fuel cooler is restricted. This could hold water back. Snake it out with a piece of 300lb monofilament. Pull hoses off cooler and snake both ways.

If temps are different check thermostats - one could be stuck. Usually they stick open and cause a lower temp reading than Yamaha recommends. The low temp engine most likely has the stuck/bad thermostat.

 

[SkunkBoat]

It could just be the timing of when you checked it. The T stats don't open until about 150Deg F. Until then the water is not flowing in the head. So you shut off the motor before the water has a chance to cool the head and it still has all that heat when you go to flush. I have experienced that on several motors.

When you run your engines to "warm up" or test, you should be able to notice the water from the telltale "pisser" warm up when the T stats open. You should also be able to see the temp drop on the Temp Gauges if you have them.

 

[Fishtales]

Check it after running at 1/2 speed if you are getting good flow from the pee hole, likely no blockage. Tstats usually stick open but can lock closed. Have you done them regularly? I do them every 3 years or so.

 

[seasick]

Check it after running at 1/2 speed if you are getting good flow from the pee hole, likely no blockage. Tstats usually stick open but can lock closed. Have you done them regularly? I do them every 3 years or so.

Its probably not a factor in this post but I would like to point out that on Mercury Optimax motors, the telltale stream comes directly from the air compressor which is directly fed from the water pump. In that design, your motor could be overheating but the pee stream is not hot. Likewise, no pee stream doesn't mean that the engine will not be cooled. It does mean though that a very very expensive component, the air compressor) is not getting cooled and will quickly fail.

 

[Fishtales]

My input was assuming Yamahas.

 

[Scout3a]

Check it after running at 1/2 speed if you are getting good flow from the pee hole, likely no blockage. Tstats usually stick open but can lock closed. Have you done them regularly? I do them every 3 years or so.

I just picked up these used engines they are F250’s 2014 with 500 hrs on them. I probably should switch out those thermostats. Who knows when the last time was when they were done.

 

[Scout3a]

It could just be the timing of when you checked it. The T stats don't open until about 150Deg F. Until then the water is not flowing in the head. So you shut off the motor before the water has a chance to cool the head and it still has all that heat when you go to flush. I have experienced that on several motors.

When you run your engines to "warm up" or test, you should be able to notice the water from the telltale "pisser" warm up when the T stats open. You should also be able to see the temp drop on the Temp Gauges if you have them.

I ran the boat the other day and she runs great no issues. Maybe it’s just me and I never really noticed it on my other engines.