Thoughts on my T Stat.

[QBhoy]

Mercruiser 5.0 MPI
t stat original and never been changed. Paint still on the seals of the housing.
The t stat is by all indications operating, but I’m beginning to think the engine runs too cool. On plane cruising it will sit around 152o. Prolonged slow displacement speed it will raise and control at around 160~. Running trimmed way up at over 60...just over 160.
The loch is very cold just now but it runs these temps all year usually. Is she running too cold ? Presuming it’s a 160 t stat that’s in her. Similar MPIs I know of are running towards 170 odd.

 

[crazy charlie]

You should probably find something else to focus on.Nothing to be concerned with except that it is orig tstat.

 

[QBhoy]

You should probably find something else to focus on.Nothing to be concerned with except that it is orig tstat.

Thanks crazy Charlie but perhaps I’m all out of focus points with this boat of mine.
It’s a point of enough concern, if it’s running too cold. Not good for it in terms of efficiency, clean burning of the fuel and proper temp for the oil and all that follows.

 

[GA_Boater]

A point of reference, QB. Last week I replaced the T-Stat in my 200,000 mile Toyota. Not because it was overheating, no, because it was running cool.

I dropped it in boiling water and it popped right open., Being the curious fellow that I am, I dropped the new in too. It also popped right open.

I fished them out and put them on the counter to cool and the new one closed in a few seconds. The old one was still partly open after 10 minutes before I chucked it the bin.

So not overheating doesn't mean a stat is still good. The new stat lets the car reach operating temp now and it runs better.

 

[Chudwick]

My 305 calls for a 160 thermostat and my boat operates at 160.

 

[QBhoy]

Thanks guys. Ga boater that’s a fair point. I’m almost sure it’s operating, but perhaps now maybe not as it should. It has never really went above 150 approx in general cruising, but as mentioned it will creep towards 160 when going slow. I’ll have a look at it.

 

[GA_Boater]

I was kinda surprised because I always thought they opened or didn't open. Now I know why the heater wasn't as hot as it should have been over the winter.

 

[harringtondav]

This may not apply to you. When I back off a sand beach or sand bar I occasionally suck sand into the seawater inlet, then it catches in my stat. When I notice the engine running cool I give 20 seconds of WOT operation. Debris flushes and temp returns to normal.

 

[aerobat]

i have a 5.0 mpi with a b3 and when smartcraft is correct it operates at 68-70 degrees celsius which is 154-158 deg fahrenheit . your numbers seem to be pretty normal.