Water temp fluctuations?

[Jasonrs]

2012 Verado 200 4cylinder 1B890671
Idles around 138-144deg water temp. Water pressure is 4 -5psi at idle
When first put on plane, water temp slowly climbs to 165, which is where my smartcraft alarm is set to go off. By the time i can flip through my alarms, it is back down to 150 or so. I honestly think if it was set at 166, it would never alarm. If i watch the water temp while running, i can back off the throttle just a touch and keep it below 160, then it will settle back to 145ish and never rise up again, UNTIL i set it down off plane, then take off again. Water pressure is over 14 psi at all times while on plane, and as high as 27 psi at wot. Psi never seems to fluctuate, just changes up or down with rpm. What is the max water temp i should see, and where should i start to look? Where is the first place that grass or debris would hang up in this system? Thanks all!!

[Erie660]

My 300 pro has done the same thing since it was new and I only have 30 hrs on it. My dealer says not to worry as long as it's not over heating but I still do not like it. I am thinking my motor needs to be lowered a little maybe. I read someone else had same issue and his dealer just unplugged something and plugged it back in and fixed his problem.

[Jasonrs]

Interesting, thanks for the info. Mine has 245 hours on it now, im finding some conflicting info on what is actually "too" hot, have read some run 160 all the time...seems strange to be getting these wild spikes up in temp just now. (Ive put apprx 60 hours on it myself)

[Jasonrs]

Update..
Took it out for an after dinner cruise last night, water temp stayed between 140 and 144 the entire time except for one wot run with the prop brought up to 1 inch below pad, temp reached 151.
Wth is going on?

[Erie660]

My 300 only seems to do it when it is rough out, it almost seems like it's a cavitation issue.

[Jasonrs]

It could very well be, my engine is on a hyd jackplate, and when it was acting up, i had the engine buried though. Would still like to hear what Mr. Weed has to say, not sure if its even a concern

[Jasonrs]

Still having this issue, any other input would be great. Don? Anyone?

[SilverFox579]

Don is on vacation until 9/6.

[ToffenG]

Hi!

My 350 Sci did the same when the sea water was cold. It fluctated between 135-175 F. However, never long time at 175F, more like sweep. The thermostat opening and closing. The cylinder block temp was stable. It was seen as normal by Merc techs. When the summer temp came in the sea, it stabilized.

My new 400R with the sportmaster lower unit stabilizes faster, and in colder water. However, when its apprx 12 Celcius, it also fluctates.

Cheeers, Toffen

[Jasonrs]

Thanks for the input, it could very well be that the previous owner had set the alarm at 165 just so he knew when temps were creeping up. Still dont know what temp is considered "overheat" or when i should start to be concerned. Im not sure that i can read cylnder block temp, just water temp

[EuropeanAM]

Not sure what you're referring to by "set the alarm at 165"... temperature alarms and thresholds are hard-coding in the PCM Calibration.

Do you have PRINTOUTS of the Run History and Freeze Frame (Fault) History? This is very important, as it may not be quite what you think that is going on.

WARNING HORN "BEEPED"

[Jasonrs]

I do not have any printouts. The gauge i have has 4 different items that seem to be customizable to come on at different readings. First is fuel level. It is set to go off when fuel is at 20 % or below. Next is bat voltage. It goes off if voltage goes below 11.5v. Then its oil pressure, cant remember what its at, and finally water temp, it goes off at 165 or above. Now when i say alaram goes off, it has never beeped or audible alarmed, just the word "alarm" on the gauge and a small bell shaped icon with an "a" inside it appears. As fast as i can scroll through the different parameters and get to water temp, its already cooled off enough for the word alarm to go away. The only way i know its the water temp is by watching it very closely and see it go to about 168 at the highest. Thanks don, much appreciated!

[Jasonrs]

Here is a pic out of my vantage view manual explaining the alarm section of operation. Hope this helps

[EuropeanAM]

Ok... thanks for clarifying that instrument.

We now know that in fact, you are NOT receiving any Smartcraft or ENGINE Warning Horn alarm. Only the "made up" alarm of this Vantage View device.

I personally had a 6 cylinder... and when running it hard, it ran in the 165-176 degree range. All day long.

I believe that you probably have no problem at all... other than the "device".

[Jasonrs]

Ok, thanks don! What temperature would you suggest i set this device to go off? Would 180 be too high? Cant tell you how much i appreciate the help. At what temp is a true overheat that would set off smartcraft alarms?

[EuropeanAM]

That would probably be just about right... perhaps even 185.

[Jasonrs]

Once again, thanks, really appreciate your input

[theredman]

I’m having similar issues with my 2016 300 Verado. I picked it up last fall when the lake water temps were 75+. I had no fluctuations in temps. It would run up to 165 or so then go back down to the 140s and sty there. No that water temps in the 50s the gauge is all over the place. Runs up to 175 then back down to 140s. Is this normal for winter time running? And can I run it like this?

[EuropeanAM]

Yes.