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

[timo27]

Hey All -

I just got a scangauge to add to the wonderful geekery that is my new Gen III . I'm noticing the coolant temp simply refuses to get much above 135-150F unless I do a 15 min+ run on the interstate. (In that case, it gets up to 190-195F, which is I think about what it should be). So, my questions:

- Anyone else noticing the same thing?
- Do you think there's anything wrong with the thermostat?
- Would FE improve with higher temps, or is it maximizing FE by doing this?
- Any thoughts as to the implications on the 'health' of the engine? It seriously won't warm up in city driving, even after 1/2 hour or so; are these temps (135-150F) sufficient to boil off all the nasty stuff and prevent condensation?

FWIW, the scangauge arrived at about the same time as some unseasonably cold weather--low 40s F (Jayman, go ahead and laugh, it's warranted ). But it does make me wonder what to expect when honest cold weather arrives (Jayman, laugh again--about -18C is roughly our record low around here...)

Anyhow, thanks to all for any insight.
Cheers
Tim

[adamace1]

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.

[a64pilot]

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.

[spiderman]

Originally Posted by a64pilot

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.

[Bobsprius]

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.

[FireEngineer]

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

[fuzzy1]

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.

[fuzzy1]

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.

[ken1784]

Originally Posted by timo27

- Anyone else noticing the same thing?

Yes. It's normal.

- Do you think there's anything wrong with the thermostat?

Nothing is wrong. The thermostat was working fine.

- Would FE improve with higher temps, or is it maximizing FE by doing this?

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

- Any thoughts as to the implications on the 'health' of the engine? It seriously won't warm up in city driving, even after 1/2 hour or so; are these temps (135-150F) sufficient to boil off all the nasty stuff and prevent condensation?

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-...-strategy.html

Ken@Japan

[adrianblack]

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??