2002 Crusader 8.1L HO steam

[Fly'n Family]

Great forum, glad to have found it and all of the knowledgeable folks on it.

My question is on a boat I had surveyed that has twin 8.1L HO 425 hp Crusader motors with 330 hours on them, all fresh water.

Sea trial was on the Ohio river, where the water was pretty cold. Did a couple of WOT runs, and the engines never got above 145 degrees, and were putting out a LOT of steam. It was explained to me that, unlike my previous 454 Mercs, these motors are both closed cooled with anti-freeze, and raw water cooled on external engine aspects - and that there was no thru hull exhaust, all exhaust was ported thru the water outflow vents. That seemed pretty clear as when she was started, the different rumble and sound level was unmistakeable.

The volume of steam and the engine temps not going above 145 deg has me concerned. Should I be, or is this normal for this type of engine in a cold water environment? Not sure of the water temp, probably around 48-50 degrees, outside tem about the same - and humidity around 65%.

https://s26.postimg.org/4az762xjt/3870_Steam.jpg

 

[Docksidemarineservices]

Normal in cold water and air temps.

 

[Fly'n Family]

Dockside, thanks for the response.

Uploaded on youtube, hopefully this will post here for viewing and commentary if this is "normal".

https://youtu.be/ncsD4XWfbFg

 

[matta0413]

Looks like about the same as mine do when I run in November. Usually you get steam when the engine is running a little hot not 145. I have 8.1's and they run around 170 in the summer and a little lower than that when cold.

 

[erich]

145 degrees when fully warmed up is too low. I believe those engines should have 170 degree thermostats. So possibly someone removed the thermostats or the gauges are not correct. You could check it with an infrared heat gun, but definitely needs to be checked for the cause.

I am not sure what "and that there was no thru hull exhaust, all exhaust was ported thru the water outflow vents." means, but if they are closed cooling with heat exchangers and antifreeze, then the engine coolant should get up to 170 degrees before the stat opens and antifreeze flows through the heat exchanger where it gets cooled by the raw water flowing through the internal coils/tubes. Then the raw water mixes with the exhaust fumes at the exhaust elbows before going into the muffler and then out a through hull which appears to be on each side of the boat.

An automobile engine works about the same, may be cold when first started but heats up until the thermostat opens allowing the coolant to flow through the radiator to remove the heat from the coolant. The thermostat may close a little to keep the engine at the proper running temp.