Normal Prius operating temp.

[hdrygas]

Originally posted by DaveinOlyWA@Feb 20 2006, 08:41 PM
no, i have nothing on that. my car warms up to 150º in an average of about 3 minutes doing city streets, this is with OAT in the 40's. i also had a few trips where temps were below freezing. one day i tracked my temps in 30 sec intervals on a day that was very cold and windy. on those days it took 5 mins to hit 150º and drove for 15 mins before temps got much above 160º

the info on my blog i posted about dec 4, (I dont have that good a memory... i looked it up) was the synopsis of 3 cold dry windy days. i also track mileage verses temps for my daily commute mostly because its short enough that the effects of temps show up more. the commute is 7.4-8 miles (depends on where i park) nearly all at 35 mph.

my averages on that trip varies from about 39 mpg @ 25º to 70 mpg @ 80+º. most of my data has temps at 45º averaging about 48-50 mpg

keep in mind that wind will play a factor. on my blog trip, the temps were one thing, but all the trips were done with a brisk wind. if you are island hopping out in the Puget Sound, there is no doubt imm that the breeze will be significant

*edit*

oh one other thing. the trips i took have no lights and a few quick stops. at the end of the route i took was a light. one day i stopped and the ICE temp dropped 5º while sitting at the light!

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Dave I would like to talk to you about a radiator blocker? It is not like we are talking hair plugs or anyting.

[DaveinOlyWA]

well, i have thought about the bra thingy...i already have 4 little chips on my car. so i will most likely do the velcro cover thing like you did. so may have to come over to examine your handiwork

[jeromep]

Allan,

Unlike Dave and others I don't have CANview or the Scangauge, although I would like a Scangauge. I also do not do any radiator blocking. However, when the vehicle finally "falls" into hybrid mode at light, I know I'm up to temperature. That is also generally when the autoclimate system starts to back off the fan from higher speeds to lower speeds. When those events happen I know that the car has reached its temperature targets. Keep in mind that the engine might have already reached its targets to go dormant at stops or when appropriate, however if your cabin temp needs heat it will continue to run the ICE for heat.

As a side note, I have never had a car overheat on me, and I've driven some pretty old and questionably maintained vehicles. All the years I was in college with friends driving equally old or worn out vehicles, I don't recall any of them being stranded or requireing repairs that were created by an engine overheating condition. Were we lucky. I don't honestly think so.

A number of scenarios lead to overheating. There has to be a loss of coolant sufficient enough to reduce the volume of coolant cycling through the block and radiator. A water pump has to fail. A radiator has to become so blocked with deposits that it no longer cycles coolant or dissapates heat well (this situation creaps up on you rather than just happening). A thermostat has to fail in the closed position.

The concern about overheating is overstated with modern vehicles. Just about everything built in the last 10 years will shut down the engine in an overheating situation, thus preventing damage if an overheating condition does occur. Engine temperature gauges are not an accurate way of determing coolant temperature. In fact most temp gauges are pretty much meaningless except that the tell you that you are either ok, or not ok. But then again, that is my opinion on the difference between having gauges and haveing idiot lights or nothing at all.

Happy motoring to you from another who lives east of the Cascade Curtain.

[Allannde]

Originally posted by jeromep@Feb 23 2006, 02:35 PM
Allan,


Happy motoring to you from another who lives east of the Cascade Curtain.

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Hi jeromep

Thank you for your thoughts. I can't recall having an overheating problem either. What I am tryiing to understand is what my temperature readings mean. It seemed strange to me for a "normal" temperature to be so near to boiliing. That makes your comments especially helpful. This thread has taught me a lot even though a much has been over my head. What you said put it very simply. Thanks again.

Allan de

[jeromep]

Originally posted by Allannde@Feb 23 2006, 03:30 PM
Hi jeromep

Thank you for your thoughts. I can't recall having an overheating problem either. What I am tryiing to understand is what my temperature readings mean. It seemed strange to me for a "normal" temperature to be so near to boiliing. That makes your comments especially helpful. This thread has taught me a lot even though a much has been over my head.  What you said put it very simply. Thanks again.

Allan de

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Allan,

Honestly, others gave you useful data, I just punctuated the thread with my opinion and sundry vehicle experience. The best thing to keep in mind is that some of the operating rules we are used to with conventional vehicles don't work in hybrid land. I don't need a temp gauge to feel comfortable driving a vehicle knowing that other safeguards are in place. I'm still curious about the operating parameters of the vehicle and as such would enjoy a scangauge, however until I chose to aford it I will remain satisified with the displays that Toyota did provide me.

Are you familiar with the concept of water boiling points and atmospheric pressure? The goal of a pressurized cooling system isn't so much about temperature as it is about raising the boiling point: the point where water turns to vapor. Water vapor (steam) in a cooling system is bad. When you have steam in the system, you are overheated. By pressurizing a cooling system to a number of lbs above atmospheric pressure you increase the temperature at which boiling occurs and thus the cooling system is able to operate at higher temperatures, removing heat from the block to the radiator effectively. If steam occurs, it creates excess pressure in the system and cooling is no longer effective along with the need for that steam to escape. The reason that vehicle manufacturers warn against removing the pressure cap when the vehicle is hot is because water in the system may be above the normal boiling point, and when you remove the pressure you have instant scalding steam and liquid pouring out of the cooling system.

It isn't uncommon for manufacturers to run their engines a little bit on the hot side. Ford has been doing that for years, it generaly increases fuel efficiency a bit and during the winter helps provide sufficient cabin heat by having thermostats that open later when the vehicle is warmer and close, at least partially, while running to retain heat in the block, if necessary.

[Frank Hudon]

most of us that use CAN-view, MiniScanners or Scanguage do so, so we can see what is happening and what we have noticed is that the Prius is very cold blooded. Takes a long time to warm up in cold weather and cools very rapidly in cold and windy weather. Have it up to temp, park it nose into the wind on a just above freezing day and loose 80-90 degrees of engine temp in less than 20 minutes. That little ICE and the fact that it doesn't have to put out a lot of power all the time means it burns less gas so produces less heat. That just physics. Now pull out a whole bunch of BTU's heating the interior and the ICE is way to cold to go into S4 and your mileage takes a big hit. My Classic with the "lips" has never, other than 2 times, this winter had the cooling fans on. If your east of the crest you could probably block it right off and never have a problem in the winter, and there is a High Temp light on the dash that will come on if it does get too hot. On to the part about how hot it runs. Since about 1967-8 all the manufactures have gone to 195 degree thermostats. It started with the emission regulations as a way of keeping them down. But goes even further back than that, Continental Engines did wear tests for various temperatures and found that the hotter you ran the engine the less wear it had. This goes back to the early 50's when those tests were done. Since then the quality of the engines has got a lot better component wise, IE: piston rings, better quality valve's and valve guides and even better oils, so hotter isn't a problem. A mix of 50/50% water and antifreeze has a very high boiling point and put it under pressure and it's probably about 245F. We have trouble getting the Prius to the high 180's. Not unusual to have the ICE temp drop 5-10 degrees waiting for a traffic light in the winter.

[hobbit]

I've got an analog coolant-temp gauge, and when stopped at a light
even with the heater fan on "low" I can watch the temp VISIBLY drop.
.
_H*

[jeromep]

Tell me if I'm right or not Frank, but isn't there an auxillary pump, other than the coolant storage tank transfer pump, which continues to circulate coolant through the loop when the ICE is off but the vehicle is on, like dormant at a light?

[Catskillguy]

Ok... Disclainers included

I don't have Scanguage or Can-view...

What is the opinion on installing a radiator block? Is it worth any risk? The temps overnight have been in the single digits to teens lately, and not much better or same over at least the next week.

I do maybe 20% local driving & 80% highway (interstate or State). I am on the interstate with no traffic in about 5 miles or 10 mins. I may do 1 stop then travel like above during the day.

Based on the above scenario, do you think it would be worth my while to do the radiator block. I have the EBH ready to install, if I can ever get the weather to bear installing in outdoors without the 0-10 below wind chills!!

Thanks all!!

[DaveinOlyWA]

Cat for your weather conditions, its a win-win situation. simply too cold even for radiator block to overheat your car. but for peace of mind, get one or the other.