❓No coolant recirc when engine is off ❓

[Mavster Mechanic]

For 3 years I have noticed this.
I have enough data to confirm.

The moment the engine shuts off, the coolant (water pump) shuts off. It behaves as if it is engine driven. But it is electric.

But why?

Those of you with a scan tool will see:

Cruising on the highway water temp will hover around 185°F.

Take foot off pedal or kill cruise control. Coast down with gas engine off. Water temp will quickly spike to 205°F or 208°F or something close.

After regen on that slow down you'll have a full battery.

Putz around in EV mode in a mall or congested area for 5 or 10 minutes. The water temp will stay high in about the same 205°F range the entire time.

UNLESS you have cabin heater on and are pulling heat to fhe cabin. THEN water temp (coolant) falls like a rock.

Weird. Now why does it do this?

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[HeyBales]

Not sure why - but sure going to help evaporate off that condensation water that some think is ending up in the oil. Of course no where to go now...

Anyway - could it be since system doesn't know how long you might be in EV mode, perhaps just sitting around with ICE cooling down, it wants to keep ICE at a better temp for next usage?
Or potential for desired cabin heat?
Was it cooler outside or you've really noticed this all seasonal temps?

Interesting catch.
This is just a 51 sec snippet from a 45 mph road and ICE turning off to EV slowing down to 35 where I stayed in EV for a bit, and temps kept rising 154 - 160. 79 F outside, so no need for cabin heat! This is right before ICE was spun up for acceleration. Cat lost 20 even.

 

[Mavster Mechanic]

I'm never below 32°F.

But the same behavior is observed year-round.

 

[Chops]

For 3 years I have noticed this.
I have enough data to confirm.


Take foot off pedal or kill cruise control. Coast down with gas engine off. Water temp will quickly spike to 205°F or 208°F or something close.

Makes sense - coolant no longer circulating with the engine off.

The EB has a “cool down / high idle” for a minute or so after putting into “park” at end of drive. Keeps the coolant & oil circulating to reduce stress on fluids & turbo too.

Seems when the Atkinson is off, the water & oil circulation stop? The heater will draw heat from the hot water but the oil is still baking.

 

[inline_five]

I have noticed this as well. My thinking is the Atkinson engine returns much better MPG the hotter it is, so cooling it down while off would impact MPGs negatively.

Ford coolant WSS-M97B57-A2 is good to 265° F, so no worries on 210°-215° F. The 0W-20 oil is good >400° F.

 

[Phimosis]

For 3 years I have noticed this.
I have enough data to confirm.

The moment the engine shuts off, the coolant (water pump) shuts off. It behaves as if it is engine driven. But it is electric.

But why?

Those of you with a scan tool will see:

Cruising on the highway water temp will hover around 185°F.

Take foot off pedal or kill cruise control. Coast down with gas engine off. Water temp will quickly spike to 205°F or 208°F or something close.

After regen on that slow down you'll have a full battery.

Putz around in EV mode in a mall or congested area for 5 or 10 minutes. The water temp will stay high in about the same 205°F range the entire time.

UNLESS you have cabin heater on and are pulling heat to fhe cabin. THEN water temp (coolant) falls like a rock.

Weird. Now why does it do this?

Makes sense to me. They don’t want the engine to fall out of the temperature operating range.

For example, you’re crossing a canyon that doesn’t have a bridge. You go to the bottom of the canyon with engine shut off for many minutes, doing regen braking. Then you start climbing up the other side and you instantly go from engine off to 3/4 throttle and 5,000 rpm. You wouldn’t want to do that to a cold engine.

 

[MakinDoForNow]

Makes sense to me. They don’t want the engine to fall out of the temperature operating range.

For example, you’re crossing a canyon that doesn’t have a bridge. You go to the bottom of the canyon with engine shut off for many minutes, doing regen braking. Then you start climbing up the other side and you instantly go from engine off to 3/4 throttle and 5,000 rpm. You wouldn’t want to do that to a cold engine.

It has been posted in the past that (excluding any other reasons) when the ice coolant temp drops to what I remember 180-190°F the ice will be started to warm the radiator up to higher end of operating range. If the heater needs heat for cabin or the HVB needs warming the electric water pump will be started and circulated to the appropriate heat exchanger.
ETA: Turn on the cabin heat and see if that turns on the water pump after a short while?

 

[Mavster Mechanic]

Makes sense to me. They don’t want the engine to fall out of the temperature operating range.

For example, you’re crossing a canyon that doesn’t have a bridge. You go to the bottom of the canyon with engine shut off for many minutes, doing regen braking. Then you start climbing up the other side and you instantly go from engine off to 3/4 throttle and 5,000 rpm. You wouldn’t want to do that to a cold engine.

How cold do you think it would get in 2 or 3 minutes?

Plus all bets are off if you have cabin heat on.

Still

It's 120°F when the engine is allowed to shut off.

If already off waiting in line or something, it is allowed to stay off until 116°F I have observed.

This is considered "hot enough".

 

[scharris99]

205 doesn't sound hot enough to worry about. I would expect it to have a 195 optimal operating temp.

 

[Phimosis]

How cold do you think it would get in 2 or 3 minutes?

Plus all bets are off if you have cabin heat on.

Still

It's 120°F when the engine is allowed to shut off.

If already off waiting in line or something, it is allowed to stay off until 116°F I have observed.

This is considered "hot enough".

They want it to be at 195 F when it starts back up. Modern engines all run around 195 F because it is optimal thermodynamic efficiency. You get the best mpg and best emissions profile at that temp. I’m betting their settings are directly tied to the optimized emissions and mpg performance on the 5 different cycles of the EPA mpg test.

 

[Mavster Mechanic]

Hybrids = 185 under constant nominal load such as cruise control 65 MPH no trailer.

 

[HeyBales]

It has been posted in the past that (excluding any other reasons) when the ice coolant temp drops to what I remember 180-190°F the ice will be started to warm the radiator up to higher end of operating range. If the heater needs heat for cabin or the HVB needs warming the electric water pump will be started and circulated to the appropriate heat exchanger.
ETA: Turn on the cabin heat and see if that turns on the water pump after a short while?

If no call for heat - 120 F, tad below before it turns ICE on for that reason.

When set to around 70-73 last winter, it was cycling ICE on to keep coolant between 123-143 abouts, depending on ambient temps.
Ranged moved higher if colder or hotter cabin temp set.

I'll have to take that suggestion to watch a PID regarding the water pump, as it's getting cooler.

 

[Tbone289]

Hybrids = 185 under constant nominal load such as cruise control 65 MPH no trailer.

Off topic I know, but that's the coolant temperature reported by OBD-II in my 4K Ecoboost for the same conditions, FYI. The EB OEM thermostat is 190 degrees, the hybrid is 180.

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