So this evening, I'm driving home and the ICE temperature clamped at 91C: Started drive home with ICE at 41C Got on Interstate spur, 70 mph ICE temp rose to 91C, outside 64 F . . . HUH? Use cabin heater to reduce ICE temp to 86C Turned off cabin heater, ICE soon rose to 91C . . . HUH? Used cabin heater to keep ICE in the 86-89 C range BACKGROUND Got Prius in late May 2009 Has 66,000 miles Due for fall oil change PROPOSED RESOLUTION In the morning, I will check the radiator coolant and top off both the overflow tank and open the cap and bring the level up. Hopefully, this is just a low coolant problem. If the symptoms persist, I'll use miniVCI to check the electric water pump status. Alternatively, take it to dealer and have the thermostat and coolant changed. Comments? Bob Wilson
HI Bob, Just to save you digging around for a radiator cap, there isn't one on gen 3. Just fill at the bottle. As always, thanks for sharing data as you you troubleshoot. You've got me curious about ice temps now, so mini VCI will be heading off with me this morning! Mike..
The thermostat is a 90C one. 90C is the correct temp. for a fully warmed up engine. We just rarely see a fully warmed up engine. 91C is within the error of your thermo measuring device. I have seen 90C a few times, but I do have to be on the highway or have my grill blocking installed with ambient above 60F. Have a quick look at the front of the A/C condenser/radiator stack. Is it plugged with insects etc.?
I checked the tank and it has plenty of fluid . . . nice pink stuff. Most of this morning's commute was below 90F until after exiting a mile long stretch of Interstate. It was up to 91F, again. Yet when I turned into the parking lot after another mile of 25 mph, it had dropped to 73F. It is time for the fall oil change. Bob Wilson
I have a C, but my runs around 87C to 90 C. It depends if I am on surface streets, Freeways, or climbing hills. My A/C is always on.
I don't understand. You started heating the cabin, and the engine coolant temperature dropped. Seems normal. You stopped heating the cabin, and the coolant temperature went back up. Are you saying there's something wrong there? Seems normal: whenever you pull coolant over to the cabin heater you use some of it's heat. Talking to you Bob, I'm pretty sure I AM missing something, but let me off gently, lol.
Apparently my usual commute is not really bringing the ICE temp to ~90C often. So I've been seeing mid 80C thinking this was normal. Just I had a couple of commutes at higher speeds and that was when I saw 90-91C. I am used to seeing the fans come on above 92C in our NHW11. I am not sure what the fan threshold is for our ZVW30. Sounds like I need to map the ZVW30 cooling system operation. <sigh> Has anyone published such a survey already? An old guy, I've used the cabin heater for extra cooling as needed dating since 1966 when I started driving. I believe Mom told me about this trick. She also told me about using the starter to move a manual transmission car out of an intersection or off the rail road tracks before 'safety interlocks' made that impossible. Bob Wilson
Sounds like normal gen 3 numbers, or at least consistent with my 2010. Here's some data from this morning: NY I87, 2 exits traveled north bound into headwind, flat for the first few miles then hilly - Southern Adirondacks, climate control off, cruise set at 72, air temp 52f. -Merged onto highway with coolant temp @ 87c -Settled into cruise on flat @ 89-90c, rpm variation ~1400-1800 -Sustained climbing temp @ 91-92c, rpm ~2800-3300 -Temps across this entire range through rollers -Immediate drop back into 80's after exiting This is pretty typical of my 2010 regardless of weather conditions and grill block, and this is a reminder that I need to block 50% lower with our sudden shift to fall. I do find gen 3 temps to be a few degrees c higher than our '07 in general. I'm guessing the gen 2 t-stat opens at a lower temp but don't know this. Sounds like the gen 1 t-stat may be more in line with gen 2?.. Anyway, your 2010 seems as "normal" as mine, Bob. Mike..
I would like to know the fan 'turn on' temperature. But like you, Fall has arrived and I'll have to wait for one of our Southern hot days to test. Bob Wilson
Block the grill and you can get the fan going easily if it's 70F or higher outside. Move to Edmonton and you'll be lucky to see 80C coolant in the winter unless you drive on the highway, and then only on a "warm" day (-10C or above). -WITH- the grill blocked.
Even on the wet coast, and 50% lower grill block, I'd concur: rarely if ever get up to 90C in winter. 70-80 is typical peak.
I might see 90C (190F) or a bit more running as blocked as I am in the summer but usually I'm in the low 180s (85+C). I'd say you are just seeing the high end of normal. Low speed driving should drop ICE coolant temp as the engine isn't spinning.
On my daily 26 mile commute with mosly highway driving I see 190-195F which is the thermostat rating.
My temp range from 90C-91C on normal driving 92-93 on +38C hot summer days. Heater is going to affect the ice temperature, mine drops from 90C-85C and takes 2-3 mins to climb back up to 90C
Note that using the AC runs 1 of the 2 cooling fans which will have an effect on the engine temperature. My Acura turns on the 2nd fan when the coolant temp reaches 215 F. I'd expect the Prius to be similar.
I just setup a cheapo $10 Android device to run Torque again, and have set an alarm to go off if the cooling fan kicks on. I'm also tracking min/max engine coolant temperatures. With my lower grill blocked 100%, I'm seeing 88 C (188 F) as a normal temperature, and a peak of 94 C (202 F). This appears to be normal to any other car I have driven. The Acura can run 214 F all day, every day without harm. Hotter engines are more efficient anyhow, up until the point that they misfire or wear excessively.
