Coolant question

[Specaled]

That is strange.

[Fat Charlie]

Specaled- I work at a dealership. From TechCONNECT:

DESCRIPTION - 3.7/4.7L
CAUTION: Do not operate an engine without a thermostat, except for servicing or testing.

A pellet-type thermostat controls the operating temperature of the engine by controlling the amount of coolant flow to the radiator. On all engines the thermostat is closed below 195°F (90°C). Above this temperature, coolant is allowed to flow to the radiator. This provides quick engine warm up and overall temperature control (Thermostat Cross Section View 3.7L/4.7L).

The same thermostat is used for winter and summer seasons. An engine should not be operated without a thermostat, except for servicing or testing. Operating without a thermostat causes other problems. These are: longer engine warmup time, unreliable warmup performance, increased exhaust emissions and crankcase condensation. This condensation can result in sludge formation.

What's unsafe? I don't know. I get scared over 212, even though red coolant at 50/50 won't boil until 265- I don't know what temp the engine doesn't like. When I was towing the camper this summer we took a rest stop when the UG said 220. I just didn't like driving at temps that high.

[Specaled]

Thank you Fat Charlie!!

[TheEnemy]

Originally Posted by redpoint5

On both my TSX and CBR600 the coolant temps rise whenever I coast in N and plummet once I let the clutch out and the engines comes back up to speed. Everyone else is saying their coolant temps drop while coasting. Strange.

Those are motor bikes correct?
That tells me your water pump does not move enough water at idle. It may be that the pumps are designed to operate at a higher rpm without cavitating sacrificing low rpm flow.

[meanjoe75fan]

^
Another reason temps might rise in N (assuming EOC) is that, without flow, you "heat-soak" the water in the block.

I know when I had my Contour, the SG used a temp sensor in the engine block (that also ran the fan, etc), and the cockpit gauge used one installed in the radiator. This meant, when I'd EOC, the SG would go UP, and the dash gauge went DOWN. (When I fired back up, the SG would drop as the "chilled" (relatively speaking) coolant that had been sitting in the rad circulated.

I don't think this peculiarity is anything worth worrying over, given that it happens each time you shut the vehicle down anyways.

[ConnClark]

I feel the need to chime in on this again.

Your engine is designed to run at a specific temp. The parts are designed/sized so that thermal expansion of the parts lines the parts up optimally at this temp. Furthermore your engine operating at the temp the thermostat sets breaks in the parts so that they work together better at the temp the thermostat sets. Operation outside of the ideal temp defined by wear and design causes excessive wear on engine parts that degrades performance/economy.

If your grill block in any way changes your coolant temps you are wearing out your engine.

[Specaled]

My engine has 256000 miles on it now, wear is a given.

[gone-ot]

FWIW, the thermostat in our 2011 Cruze with 1.4L turbo engine has these specs:

221ºF start opening
243ºF fully open

[ConnClark]

Originally Posted by Specaled

My engine has 256000 miles on it now, wear is a given.

mine has 251,000 but I can expect to get at least another 100,000. If you want to push your engine to an early grave go ahead.

[LeanBurn]

Wow, that is a high opening temperature. My Corolla opens between 176-183F.

I see it like this, the aero mods still have to allow effortless cooling to the engine, if the fan is coming on while at speed I have too much blocked. The power needed to run the fan starts to cancel any gains the aero might have achieved....and I totally agree that if you run too close to the maximum allowable temperature you are flirting with disaster, there is no room for error or odd random temperature spikes. Not worth the mpg unless you don't care about your engine.