Toyota Prius Forum banner

1 - 16 of 16 Posts

·
Registered
Joined
·
216 Posts
Discussion Starter #1
My Scanguage arrived yesterday. Can someone tell me what the optimal coolant temperature is? I imagine it would be just below the point where the thermostatically controlled coolant fan kicks in. From the 50 miles or so that I drove yesterday the coolant temp didn't seem to go about 185F. I'm wondering if it is time to take off my winter lips.

PA P
 

·
Registered
Joined
·
582 Posts
keep your lips

The engine coolant thermostat is right around 180 oF 82 oC The engine fan is about 200 oF 94 oC. Easy to check with your new gadget. I believe that the A/C starts both those fans, yes?

I have cardboard in front of classic Prius radiator and I'm in no hurry to remove it.

DAS
 

·
Registered
Joined
·
216 Posts
Discussion Starter #4
Thanks, this is helpful. It sounds like the winter lips should stay on until the coolant temperature hits 200F.

PA P
 

·
Registered
Joined
·
22 Posts
Maybe, except that the engine isn't the only thing being cooled by that airflow. The inverter need to be cooled, too, and may have a higher demand depending on the driving cycle. Folks with CAN View have reported that it stays in the OK range with ambient temps up to 50F, but the grille blocks need to come off after that.

Obviously, it's a lot easier to make the decision if you have direct access to that info in real time.
 

·
Registered
Joined
·
7,166 Posts
When the fans are not operating and the car is not moving, so that there is no air circulation through the radiator, the coolant temp will rise until the fan thermostat kicks in to start cooling things down.
As stated, if the AC is on, then the fan will always be on, thus the coolant will always be on the lower side of the limit.

This has caused a few concerns with Saturns that have a wide range between the low coolant thermostat opening temp, and the high temp that trips the fans to be on. Usually the Saturn is either moving, using AC, or ambient temp sufficiently cool that the coolant temp doesn't rise much past the low normal temp. But be stuck in traffic on a day where the temperature is moderate where AC is not needed, and the coolant temp rises to temps that some would find a bit too high.
I had discovered this phenomina with my SL2, and tested that this was normal by letting the car idle until the fan kicked in. Once the fan kicked in, the temp went down considerably.
Later my cousin who had an SL1 and a friend who also had a Saturn (but I don't remember the model) mentioned their similar concerns and I was able to relieve their fears based on my observations.

So, yes. the coolant temp probably does vary quite a bit. It may even get below 180 degrees when at prolonged stops with the ICE mostly off.
 

·
Registered
Joined
·
144 Posts
Hurray for ScanGuage

I just got mine Saturday and I love it to answer your question I couldn't get over 184 F. ok back to playing with it
 

·
Registered
Joined
·
582 Posts
getting hot

Highest temperatures observed in 2001 Prius, using Graham Davies miniscanner.

Engine coolant: 96 oC (radiator fan is spinning and the system seems adequate even in summer heavy-load driving).

Inverter coolant: MG1 inverter about 95 oC with a lot of short-term variation. Apparently this was where Prius designers had to put a lot of design effort. MG2 inverter does not get so hot.

Motor/gens: MG1 (the motor itself) is actually the most interesting, and I've seen it at 105 oC. If it ever reaches 120 oC, I'm pulling over because somewhere above there the winding insulation is at risk ( 140oC perhaps?). MG2 does not get so hot.

HV battery: Have seem max cell temperature at 48 oC. When it's hot I turn on the A/C in flow through (not recirc) mode. Cooling then occurs at about 1 oC per 5 minutes. NiMH batteries prefer temperatures below 45 oC I've been told.

The MGs in the new model Prius are of a more efficient design, so I would anticipate lower max temps in those.

DAS
 

·
Registered
Joined
·
2 Posts
On a 07 Prius how does one know without a water temperature gage.

Has anyone here added a temp gage? I'm thinking of adding one.
 

·
Registered
Joined
·
2,243 Posts
mdskier said:
On a 07 Prius how does one know without a water temperature gage.

Has anyone here added a temp gage? I'm thinking of adding one.
If you look at the original post you will see they are using a Scangauge to read the coolant temp.
 

·
Registered
Joined
·
1 Posts
On a 07 Prius how does one know without a water temperature gage.

Has anyone here added a temp gage? I'm thinking of adding one.
Just use a ODB2 scanner with your phone. there are tons of great apps out there. If you use an iPhone make sure to get a Bluetooth 5 one, nothing below that will work with the any phone over 5 I believe. If you have Android, I believe a bluetooth 4 will work. There is WiFi also, but if you do that, and you want to use a tablet, you cannot also use the WiFi at home at the same time. You do not need WiFi to use ODB2 but it is nice to have both. There are also USB if you want better tools and a computer. You can use Bluetooth or WiFi on a computer too.
 

·
Registered
Joined
·
1 Posts
My Scanguage arrived yesterday. Can someone tell me what the optimal coolant temperature is? I imagine it would be just below the point where the thermostatically controlled coolant fan kicks in. From the 50 miles or so that I drove yesterday the coolant temp didn't seem to go about 185F. I'm wondering if it is time to take off my winter lips.

PA P
Japanese Prius Tech Manual says the thermostat specification is starting to open at 82C (180F) and fully open at 95C (203F).
We see the typical coolant temperature is about 88C (190F).

[email protected]

Prior to flushing my coolant I noticed my coolant temperature was at 100 deg Fahrenheit. After the coolant flush my coolant temperature is around 150 deg Fahrenheit while idle and reaches 176 deg Fahrenheit max (that I have been able to observe while driving). Should I be concerned about this?

Thank you
 
1 - 16 of 16 Posts
Top