Help, nearly no heat!

Hi rvndave,

Since you have a scangauge or other device for seeing engine temp, then your all set to grill block. In this weather, block the top grill completely, and the passenger side of the lower grill. Use pipe insulation. DO NOT USE styrofoam.

With the grill block described, you should get coolant temps into the 190s.

Do a search on Prius Chat for Grill blocking for a myriad of articles on this topic!!!

 

Check your thermostat. If it sticks open (as all are want to do), you will have this symptom. Replacing it is a low cost repair.

JeffD

 

The problem is the Prius engine is more efficient than most, so there is little waste heat. Even when the thermostat stays closed, the blast of cold air on the aluminum engine block cools it fast.

This is why everyone is grill-blocking. If you don't want to do it, then buy a less efficient car and burn more fuel! :-P

Even here in the relatively mild winters of the San Francisco Bay Area, I have the same issue.

Toyota should really consider a grill actuator. That would solve the problem and help mileage in the winter when air is denser by improving aerodynamics.

 

pEEf took the words out of my hands WRT a more efficient engine having less waste heat. I block 100% on the bottom (2010 model) and just drove about 10 miles in 3 spurts with 20 minute breaks in between each leg and by the time I arrived, it was quite warm in the car, probably around 55-60 degrees and it was 19 OAT. The heater definitely pulls the water temp down and will affect mileage so you have to decide if you are after comfort or MPG. You can run the heater on a manual setting and find a happy medium, as the heater on auto will favor comfort. I don't look at it as a loss of MPG in the winter but a gain of MPG in the summer which is something conventional cars can't do as their mileage is comparatively poor all year long.

 

dave, it looks like its really cold where you are in ohio correct???
its sucha small engine it takes a long time to heat up and doesnt retain heat well, running the heater robs it of needed heat to make top efficiency mode aka top mpg.
your own description confirms this. you went from 43 to 51 mpg when you turned the heat off.
i have also noticed that its hard to get much heat in the winter, if you do, it kills the mileage.
block the grill!!!!!!!!! i did, i am in philly. you can fully grill block at all temps below 50 degrees, especially if your trips are 20 minutes or less.

 

I think the problem can be solved with a high temperature thermostat. The standard one is 180 degrees. A 195 degree model would be better. I have not found source yet. Anyone know of one? Grill blocking is my second choice if a high temp thermostat is not available.

 

I happen to have one 88 degree C thermostat, made by Tama Enterprises in Japan, model number WV56TA-88. It also comes with the rubber O-ring. Ken1784 sold this to me a couple of years ago and I did not use it since I moved to a relatively hot area. If anyone is interested in buying it from me please send me a PM.

 

Patrick:
that is 190 F. Has anyone tried it, does it help?

 

No this will not solve it. If the engine temp is staying around (or below) 170, then the thermostat is never opening in the first place. All the cooling loss is due to the blast of cold air hitting the large surface area of the bare aluminum engine block. (and the heater core inside)

You could outright remove the radiator and it would still happen!

This is why many cars that are sensitive to cold, such as Diesels, have louvers or some other way to prevent air from entering the engine compartment. Most semi-trucks operated in cold climates have grill blocks.

My old 1980 Peugeot diesel came with a snap-on grill block in the trunk.

The best way for Toyota to solve this would be motor operated grill louvers that automatically close when cooling isn't needed. This would also help aerodynamics, but it does add expense.

The Prius is especially sensitive to direct air cooling as it's engine is small, highly efficient (Atkinson Cycle), doesn't idle (total loss), and made out of highly-conductive aluminum.

 

I think the original intent of using higher temperature thermostat in the Prius is to run the engine hotter to get better fuel efficiency. The downside of that is releasing more unwanted pollution into the atmosphere.

 

True, a higher combustion chamber temp implies greater NOx production.

 

It is a common problem in any car. No one says you have to block it! But if you want better FE and warmth during cold weather then it is just a good idea? But you can also dress warmer! Class action, Shissssssh!!! Some times I wonder? H

 

1. Have you tried selecting MAX HEAT as a temperature choice? That will force the heating system to produce the most heat possible. (Of course, this also forces the gasoline engine to run more than it otherwise might, but energy efficiency may be less important than passenger comfort.)

2. Your powertrain (including the gasoline engine) is covered by a 5 year, 60K mile warranty. If you search PriusChat you will find very few reports of gasoline engine failure. Usually such reports can be tied to lack of timely engine oil changes. You need not worry that the gasoline engine will suffer unusual wear due to wintertime driving as long as you observe 5K mile (or 6 months, whichever comes first) engine oil and oil filter changes.

3. Its highly unlikely that Toyota will offer you written assurance that the grill block modification is OK. Different owners exercise varying amounts of discretion when it comes to this: Some owners think it is OK to leave this blockage in place up to 50 degrees F. Others think it is OK to leave this in place during the summer, and are then surprised when the powertrain overheats during a mountainous climb. Therefore it is more likely that your dealer staff will advise you against such a practice.

4. Although the car comes with a heating and air conditioning system, there is no spec that says the cabin temp is guaranteed to reach 70 degrees F after x minutes has elapsed, without regard to ambient temperature. If you for example visit Death Valley in July when ambient temp is 120 degrees F and leave the car parked outside for much of the day, you may find that the air conditioner takes longer than normal to cool the car down when you return. It is not clear that an attorney will find substance to your claim.

5. When you take your car in for service, it will be possible for the tech to measure engine coolant temp after the engine has run for a while, and also use a handheld IR thermometer to determine the temp of the radiator hose attached to the thermostat housing (which will show you the approximate temp of the coolant in the hoses.) If there is a large difference between engine coolant temp and the coolant in the hoses, that will be evidence that the engine thermostat remains closed. You would expect the thermostat to stay closed until engine coolant reaches ~82 degrees C or ~180 degrees F.

 

Hmm,

People have actually wrapped fiberglass insulation around the 2nd Gen Prius engine in winter operation, without ill effect.

You seem to be concerned about long-term damage due 140 F operation, AND damage due to overheating. You can't have it both ways. Car companies put idiot lights in cars to tell people to stop running their cars due to temperature excursions, amoungst other things. If the idiot light is not on, its OK. There is not an idiot light for the engine being too cold.

Seriously, go read the basics of automotive lubrication over at BITOG (Bob is the Oil Guy) dot com. The faster you get the engine up to the temp the oil is designed for - 190 F, the better. You do have a thermostat, and a gauge. So, if the engine gets over 210 F, just crank the cabin heat and pull over, and pull some of the blocking out.

The only air-blast cooled part in the Prius is the transmission. Its easy to just leave the driver side 1/3 of the lower grill unblocked, and you will never overheat the transmission. If you would have taken my advice and read those articles on here about 2nd Generation Priug grill blocking, you would have learned that, rather than have us spoon feed you....

 

I recommend you leave a small portion of the lower part of the radiator open as this is the section where the Inverter coolant loop lives. The inverter will be happiest when it's cold. This also cools the "transmission" after it cools the inverter.