Coolant temp--doesn't want to warm up (?)

My guess is everything is fine. You need to burn gas to get the engine wram, and this car is not ment to do that. It also explains why it warms up on the interstate cause your burning gas most of the time.

 

Doubt there is anything wrong, just not using enough fuel to generate the heat. I would assume you are a canidate for grill blocking. You have identified the "problem" and have the means now to do something about it.
FWIW Lycoming and Continental (aircraft engine manufacturers) have tagged 180f as the min. oil temp that you need to maintain to "cook" off moisture, acids etc. Oil temp usually follows coolant temp, but is a little higher in a liquid cooled car. I said usually, but I have not witnessed any that didn't.
My opinion is that if it were "better" for the engine to operate at 135f or so, Toyota would have used a 135f thermostat and not a 195f degree one.
Is there a thermostat? This may seem a stupid question, but with an electric water pump, I could see how the pump could be used to regulate temp making a thermostat unnecessary.

 

I was wondering the same thing. If I was betting, I would say it does not. A varible speed electric pump would probably be much more effective.

 

Timo27,

I can't tell you what the Coolant temp is in my 2010, since I am not into the scanguage's. I can tell you that living in Buffalo, it's been pretty cold at night. (mid 30's and lower) and I have heat rather quickly in this new model. In fact, it's heater far beats any other earlier Prius Gen 1, and my Honda Civic Hybrid, (In fact I almost always was cold in the winter in the civic..to my dismay).

So I am not sure if it's due to the Exhaust Heat Recirculation for reduced engine warm-up time or just better design. I can get the Gen III to "cook". Since your in Baltimore and not typical to see the Buffalo winters...I am sure you find it to be great! I am loving mine already and love the fact I can again be toasty warm in winter.

 

There is a 190F thermostat. There is a variable speed electric water pump. And to get into full hybrid operation the coolant temp must get to 157F. In city driving, stop and go short lengths, it can take a number of miles for the Gen III to warm up to 157F. Fully blocking your lower grill and half your upper will keep more of the heat you do develope and get you heated up faster. And the exhaust heat recovery system does work very well above 40MPH to warm up fast, but not in real city traffic.

Wayne

 

I should time mine, but don't believe it takes anywhere near 15 minutes on the freeway to get up to temperature. But I haven't been running it in cold temperatures yet. And off the freeway, with any cabin heat running, it can cool remarkably fast.

 

I watched the warmup today. From a cold start of 57F (air and water), it was not hot at the freeway entrance just over a mile away, but the next glance at the ScanGauge at 3.1 miles found 186F. Before the freeway I hit three very long red lights, so the whole warmup was something under 9 minutes. By the 15 miles that you are needing for warmup, I had already cycled between mid-190s and high 170s at least twice.

After sitting for three hours, it had a warm start of 107F water in 61F air. With a speed limit of 50 mph, and a significant downhill that delayed the warming process, it hit 180F at 2.5 miles.

I added a lower grill block this week, which would have sped up the warming a bit. But I doubt that it cut more even a mile off the warmup distance.

 

Yes. It's normal.

Nothing is wrong. The thermostat was working fine.

The best coolant temperature is 88C(190F).

I believe your climate control was ON, and the heater was consuming a lot of heating energy.
As Wayne stated, you'll see some improvement by blocking lower grill.
http://priuschat.com/forums/gen-iii...62556-2010-prius-grill-blocking-strategy.html

Ken@Japan

 

In pure stop and go city driving in LA, my temp is usually between 155-165F... I noticed running the heater brings the temps down pretty quickly.

In my old Protege, I would leave my apartment and by the time I was about 4 blocks away at Crescent Heights, I was at 160F. With the Prius, at the same point I'm usually only at 130F. It takes several more blocks before I hit 160F.... then I go to full hybrid mode and it uses the engine so little the temps sometimes drop below 157F.

I'm starting at 65-70F in our warm LA mornings.

Did it really take 15 minutes of engine operation to reach 190F??

 

I had a lot of trouble getting cabin heat last winter, and suffered from frosted windshield in my Gen II. I pulse and glide a lot, use a SGII to monitor conditions. I'm getting 3.9 l/100k in summer (60mpg) and about 4.2 in winter. It seems that with cold ambient temperatures you can either try for good gas mileage but with a very cold engine (I would rarely see the coolant above 70 degrees C, even with grill blocking), or bite the bullet and let the ICE run, and be comfortable. I'm not sure that a cold engine starting and stopping is a very good thing. This winter I'm planning on using cruise more, doing a lot less gliding, and looking forward to spring.

 

I suspect an EBH would help too?

 

Tim,

My experience over two winters here in Charm City in my '08 suggests
that what you are seeing is typical for a bone stock Prius. Other
posters have pretty much addressed the technical questions that you
raised. This will be a more personal, seat-of-the-pants discussion.

We tend not to think of it, but most of the energy in the gas we buy is
turned into heat. Yeah, we bought the gas, but we almost never think
of the unused heat it generates as something important. In the warm
months it is something we want to get rid of ASAP. In the cold months
however, it is a resource that we need to try to hang onto. So, how do
you do that?

It's all about retaining heat in the engine bay.
1. Grill Blocking - There are lots of threads on this. For the Gen II, the
standard practice is to use plastic foam pipe insulation pushed into the
spaces in the upper and lower grills. I expect it is the same for the
Gen III. In my experience, the grayish stuff for 3/4 in. pipe is a better
buy. (About $2 for a package of 4 pieces, you'll need 2 packages for
both grills.) It lasts longer and doesn't get sticky and leave a residue
as does the more expensive, but prettier, black stuff. (I'll have to pull
one or two pieces in the lower grill if Marty Bass is correct and temps
go up to 70 degF later in the week.)

FWIW, I keep the upper grill blocked year 'round. I too am running
with a ScanGauge. Even in the late summer, I've not seen temps
above ~196 degF for any meaningful time, either around town or on
my jaunts to New England.

2, Engine Block Radiant Heat Reflector - This is a new twist that I'm
trying to retain even more heat. The results aren't really dramatic, but
I am seeing some reduction of the rate of coolant temp drop when
stopped with the ICE off or in a no-arrows glide. Every little bit helps.
Read about it here:

http://priuschat.com/forums/gen-ii-prius-modifications/70513-ice-radiant-heat-reflector-gen-ii.html

3. Use of the cabin heater - It definitely makes a difference in
FE/MPGs, especially in the first minutes of the warmup cycle. More
heat in the cabin means less heat in the engine bay. Use it as little as
you or your passenger can tolerate.

4. Active thermal management - With the SG, you can see exactly
what's up with the block temps. Once you're used to juggling two balls,
SOC and MPG, you can add a third, water temps. Sometimes when the
HSD wants to go into EV mode, I'll give a slight push on the go-pedal
to keep the ICE turning over ever so slowly to keep the water temps
up.

5. Getting block temps quickly up to 157 degF - This is important. One
of my global rules is to try not to burn any fuel when stopped. I want
to get the most out of the fuel I use; motion and heat. In the Gen II at
least, once block temps are above 110 degF I can use my after-market
EV switch to force ICE-off when stopped. Yeah, the block cools off
some, but that's what the radiant reflector is meant to counteract. In
the cooler months it simply takes longer, both time and miles, to get
to 157.

6. As patsparks notes, an Electric Block Heater (EBH) will make a huge
difference in the time/miles needed to get block temps up to 157 degF.
I don't have a close by outlet where I park, so this is not an option for
me. But it should be one of the first things you consider. They are
available from the PRIUSchat Shop, and are lots of threads on installing
them in the Gen II. I suspect the installation hasn't changed much for the
Gen III.

Hope this helps.

PS: Tim, maybe you'd consider getting together over a cup 'o coffee.
I'd love to get a short ride in a Gen III. Maybe there are details of
the Gen II that interest you. PM me if you're interested.

 

The Gen 3 stops the ICE when at 0mph when coolant temps are anything over 103F. It will often run right up until the point you come to a complete stop, though. So at 1mph it will be running, then stop right at 0mph.

You can then keep it off until the HSI goes over the middle line -- BUT, if the temps are below 157F the ICE will not always shut-off on coasting (foot off the go-pedal) and it certainly won't shut off when cruising with the HSI to the left of the middle line. Once you pass 157F, if you start the ICE by brisk acceleration and then revert to a cruise by moving the HSI to the left, the ICE will shut off if under 43mph. (Might take several seconds.)

To force it off when cruising (and fully warmed up) just let off for briefly then keep the HSI to the left of the middle. This also works when under 157F but (it seems) you have to been driving over 103F at least for a few minutes....

Anyway, I try to maximize my warmup speed by never letting off the gas pedal when under 157F to make sure the ICE runs as much as possible (under light load) which just results in warming it up and charging the battery. (Of course, at a stop I let off, hehe.)

Today on the way to work I was at 160F in less than a mile of stop and go city driving. (Maybe 4-5 minutes.)

 

Prius acts differently in the cities between warm Los Angeles and cold Baltimore.

Ken@Japan

 

Ken, you are truly the Prius Temp guro
:rockon:
Respecting your opinion on the topic of coolant and ICE temps, I thought about you when I read the data below, on the Lexus hybrid SUV temp setup:

".... The RX 450h [] utilizes an exhaust heat recovery system, that consists of a thermostatically operated butterfly valve behind the catalytic converter which restricts the exhaust stream during warmup, and diverts much of the exhaust heat to a heat exchanger.

Heat from the heat exchanger warms up engine coolant, which then transfers heat to intake manifold coolant passages as well as the cabin heater circuit, enabling the internal combustion engine to turn off earlier, more often, and for longer periods of time, while maintaining low emissions at startup. The result is an improvement in both fuel economy and emissions.

The exhaust heat recovery system used in the RX 450h is simpler and less expensive to construct than the coolant heat storage system (CHSS) uses on Toyota’s current Prius, which employs a stainless-steel 3-liter coolant heat storage tank, two electric coolant pumps, and a motorized coolant valve assembly to carry out similar functions ..." ​

.

So now, for my question. If the exhaust heat recovery system is better, why doesn't the Gen III use it? Or do they?

.

 

I agree, Ken is one of my experts too. :thumb:

I did see the drawing of the Gen 3 exhaust system on the TIS site so I'll have a try at your question. Yes I am happy to say the Gen3 does have an exhaust heat recovery system. The engine coolant is plumbed down through a heat exchanger that is located between the second catalytic converter and the muffler. Exhaust gas and coolant flow through the heat exchanger and flow is regulated by thermostatically controlled valves.

 

The Gen III Prius does have the exhaust heat recirculation system.
Toyota Vehicles : Toyota Reveals All-New Prius / Toyota
"In addition, an exhaust heat recirculation system reduces heat waste by warming engine coolant during cold startup, for improved performance. It also heats up the passenger cabin more efficiently."

Ken@Japan

 

Heat energy recovery is the latest gen technology. This tech is unheard of in Honda, Ford and GM hybrids. 2010 Prius, RX450h and HS250h have this tech.