QuickSilver Thermostat Guage Barely Moves From Cool Point

[akendall]

Folks - I installed a new QuickSilver thermostat in my boat and connected it to my Mercury 1986 115HP Inline 6 and the needle barely moves from the cool point even when the engine has ran all day.

I had a reputable Mercury dealer take a look at it and they confirmed that the new thermostat (that I didn't buy from them by the way) was properly installed and is working in good condition. Their explanation for this is that the Mercury 1986 115HP Inline 6's typically run cool (100 - 130 degrees F) and that there really isn't a need for a thermostat on these engines because it has an alarm and auto shut-off should the engine reach a critical high temperature.

Seeing as many of us share this type of engine on this site - I was wondering if I could get a second opinion here.

Any feedback is appreciated.

thx!

 

[Silvertip]

Re: QuickSilver Thermostat Guage Barely Moves From Cool Point

You didn't install a thermostat gauge. You installed a temperature gauge. Did you install a new temperature sensor or did you connect to the sensor already on the engine? The problem is that the gauge and sensor (either new or existing) is not calibrated to measure the operating temperature of the engine. If you connected to the existing temperature sensor on the engine I urge you to forget the gauge and reconnect the alarm. Unless you watch the gauge religiously you would never know the engine is overheating. If you insist on having a gauge, get one that can properly read the engine temperature and do not disable the audible alarm. One day you will regret that if you do. To make this a little more clear, the mechanic is right when he says engines run cool. Temperature gauges are calibrated in a few temp ranges. An outboard gauge should read from 60 degrees to 200 or so. The low end is critical because these engines run cooler than car engines. Most gauges I see are in 100 or 120 to 240 degree range. Obviously at 100 - 130 degrees would mean the gauge barely moves off the peg.

 

[Texasmark]

Re: QuickSilver Thermostat Guage Barely Moves From Cool Point

The tower doesn't have a thermostat like a car that deliberately stays closed till the opening temp of 180 or 190 or wherever is reached on an engine that will run comfortably at 210 or so.

It lets the ambient water flow freely (lots of it) and the actual temp should be not too much higher than the water temp. So if the water is 80F the internal water temp should be around 95-100 I'd say.

I had an '89, which was the last year that they came out (or thereabouts) and it had none, and the water from the pee hole was never hot, nor was the engine.

HTH,

Mark