Some of you block the radiator with cardboard to get the engine warm quicker - it works. Some trucker even have kits to block their's. It starting to get too hot for that in the Sunbelt.

My coolant temperature generally peaks at 198F according to ScanGage. Saturday I drove 210 miles on the interstate - outdoor temperature 75F - I was cruising 65mph. Coolant temperature reached 227F Put the heater on to keep it from getting higher then removed the cardboard at the next stop.

61.5mpg lifetime - 82mpg in recent months

Best Run >
www.cleanmpg.com

"fanatic" is what the lazy call the dedicated

I dont know if its worth the risk to save a few extra cents? I'm an alaskan cruising this board for a potential purchase, the Cardboard trick really makes a huge difference, but when its 75 outside and your risking an overheat, it just doesn't make sense to me.

Although from what i've seen you hybridites seem to love pinching the pennies


plus, what about this, when your running hot, no doubt the computer is running the cooling fans at full tilt. These electric cooling fans, I assure you, are not small, nor their power draw negligible. You'll most likely find them on their own 15 amp circuit. Powers gotta come from somewhere!

Additionally, what about the effect on drag? The cardboard is in effect, blocking air from going where it naturally wants to go. While minor in relation to the rest of the drag-causing effects of the vehicle, once again, its real.

I once toasted a car because I figured the cardboard didn't matter. I overheated it (probably to about 270). Threw a rod a month later. Son of a *****. So maybe i'm overreacting. Although, it was a really crappy car.

The key is watching the coolant temperature. It does not rise to the point of being dangerous unless it's a long trip in warm weather for me. Many truckers even have kits with this and have had no problems.

61.5mpg lifetime - 82mpg in recent months

Best Run >
www.cleanmpg.com

"fanatic" is what the lazy call the dedicated

I just realized that my car, even with radiator block, always ran about 190'F all Fall, Winter, and Spring. The cardboard was removed about the start of May. Coolant water stayed about 190'F.

Now summer is here. This week I've had several 100'F days.
My water coolant is now running about 168'F to 170'F!!!
Even at highway speeds! Even going up slight hills!
What's going on???????????????????????

Turns out, on those 100 degree days, I was also running the A/C for the first time in about 9 months. The A/C runs the front engine fans ( there's 2 variable speed fans side by side) at 100% to cool the refrigerant in the A/C condenser, no matter what the engine temp is. Net result = the A/C cools the engine too!

And 225 F will not harm anything. The coolant will not boil until it's at least 20F hotter than that. The engine is more efficient at the higher temps as well.

Pearl is a
2007 Driftwood Pearl Prius
Package "B" (everything but leather, nav, and rear camera)