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Discussion Starter #1
Today's tech tip (I wonder when I'm going to run out of these):

Your engine operates most efficiently around 185F (85C). That's hot. That's not a problem, as long as the car is moving into the wind or the radiator's electric fan is cooling down the radiator enough to maintain that 185F. However, add in using AC, a very hot day, excessive idling, or towing, or all of the above and now the cooling system has trouble coping. Fear not, as the radiator in your RAV has 2 fans. One is for the AC condenser (it sits in front of the actual radiator), the other for the radiator. They can function independently or together as needed.
The problems happen when you shut off your engine. The engine, oil, radiator, exhaust all stay hot for a very long time. This heat builds up under the hood and the temps can really start to bake in the engine compartment. The battery is the most susceptible to high heat damage. Batteries like warmth to produce their electro-chemical reaction. But those high temps are too high, and the battery's life will be substantially shortened by constant underhood baking. The average life of a car battery in Phoenix AZ is about 1.5 years. Heat will ruin a battery long before freezing cold ever will. Cold just slows a battery's electrochemical reaction.
The other problem with under hood heat is its effect on wiring and more importantly, vacuum hoses and tubing. If the automakers used silicone tubing, there would be no problem. But that might add a few $ to the price of your RAV, so that's out of the question. Instead they use the cheapest tubing that will do the job while the engine is within its warranty period. After that, tubing starts to crack with age, vacuum leaks form, and now you get trouble codes from all the sensors under the hood.

Is there a solution?
Yes, but it's not very convenient. If you can, open the hood on your RAV when you park it after a very hot or demanding drive. I know this is an impossibility if you're nowhere near your RAV in a public place. If you can't open the hood, try parking into a breeze or wind. That helps somewhat. But at least at home or in your garage, leave the hood open for an hour or so. You'd be amazed at how fast everything cools down. Try the opposite. Leave the hot engine to heat soak for an hour with the hood closed. Then open the hood. It will feel like you opened the door to your hot oven.

The faster you can cool down the engine and under hood area, the longer your battery and parts will last.
 

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I guess I never really stopped to think about this much before. Cracking the hood would be good when I get home from work and put it in the garage. I worry about forgetting that I did that and leaving the next morning with the hood slightly ajar. To avoid that, I'd be probably best to just open it all the way up...not going to leave with it that way!
Thanks bigbird
 

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Lol, I don't think the 99 civics driving around ever did this, and although I believe it... I won't be opening my hood after a drive. I guess I'm lucky I live in NYC where the max temp outside is around 100F on a REALLY REALLY hot summer heat wave... AZ cars are much more fragile and worn out obviously.
 

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Doubt this is necessary. I've had numerous vehicles run reliably past 100,000 miles with no degradation of the rubber hoses or other components. In my Lexus, with an arguably more packed engine bay, the OEM battery made it just past 100,000 miles. I've never had a battery last less than 5 years except for the OEM one in our Plymouth Voyager which failed in one year. It's replacement went the remaining 7 years we owned that car.

We certainly get plenty of heat and slow traffic in and around Los Angeles.
 

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Someone told me that before you turn off the car, listen closely to your engine if the radiator fan is still running. That fan is running because it has to cool down the engine even if only for 5-10 seconds. Turning off the car before the fan stops can cause some major damage in the long run.
 

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......and that's why I installed the gas charged hood lifts.......I constantly raise/leave the hood open. I like being able to raise the hood "one handed" and not have to mess with a prop rod.
 

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Doubt this is necessary. I've had numerous vehicles run reliably past 100,000 miles with no degradation of the rubber hoses or other components. In my Lexus, with an arguably more packed engine bay, the OEM battery made it just past 100,000 miles. I've never had a battery last less than 5 years except for the OEM one in our Plymouth Voyager which failed in one year. It's replacement went the remaining 7 years we owned that car.

We certainly get plenty of heat and slow traffic in and around Los Angeles.
But you have the I4 which generates a lot less heat than the V6. My batteries seem to last just a tad over 2 years before failing.
 

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Some vehicles will turn on one or more cooling fans after the vehicle is stopped; walk thru a parking lot on a hot day, and you'll hear a few doing this-can't remember the particular models. I assume these have sensors to detect such a 'heat soak' and kick on a fan for a minute or two.
Any idea if the 4.4's do this?
 

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It sounds like a good idea. It certainly can’t hurt to raise the hood in order to dissipate the engine compartment heat. But I think most people would soon tire of propping the hood open.

If engine compartment heat were a major problem, auto makers would design heat vents in the hood to allow the hot air to rise. And if a car were to have an engine compartment fan that runs after engine shut off, it would drain the battery and can weaken an already weak battery. Engine compartment heat is more of a problem with turbo engines than a N.A. (Normal Aspiration) engine which is what the RAV4 has. My 300ZX turbo needs to be idled for a couple of minutes after a high RPM run in order to cool down the turbo. If I don’t, then oil coking can occur. Coking is when the oil gets so hot that it solidifies inside the turbo resulting in turbo failure.

 

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Discussion Starter #13
If I don’t, then oil coking can occur. Coking is when the oil gets so hot that it solidifies inside the turbo resulting in turbo failure.
No turbo engines produced today require idling to cool down a turbo, including Nissan's crazy GT-R. Your 300 ZX relied on oil cooling only for the turbo. Today's turbo's are liquid as well as oil cooled.

Also, your engine was designed and produced long before the advent of SN rated engine oils. Using an SN rated full synthetic oil would likely alleviate any concerns you have about oil coking from a hot soak.
 

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Off on a tangent here...When I bought my 1st jetski, a friend told me to take off the hood (in the garage) after each use to let things dry out overnight. 15 years later, thing is still running strong, and the battery lasted 12 seasons. I realize a jetski is used in the water and has a near air tight engine compartment, but there is logic behind this strategy for cars in certain environments...
 

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Now on my THIRD battery since new purchase in Jan. 2009, I can attest to heat wiping out batteries. I've yet to ever have one go more than three years, most far less.
I did notice when checking the water in the battery that the cell nearest the engine is always lower in volume than the rest....that one gets the most heat.
 

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luckily here in edmonton I'm doin good if I even need to turn on the AC let alone even need to consider opening the hood :D
 

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Here in central Texas which regularly gets above 100 degrees F, I expect battery life to be pretty short in the RAV. My '07 HHR still had the original 6-year old battery in good condition when I traded it in. The battery was next to one of the the rear wheels...not in the engine compartment. I think that helped.
 

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The battery was next to one of the the rear wheels...not in the engine compartment. I think that helped.
I believe that's the main reason GM put the battery in the trunk. Otherwise, why would they spend the extra $ on a long positive battery cable to the engine compartment and the extra venting needed for the battery. The old Cobalts, Saturn Ions, and HHR all had their battery back there. I'm not sure about the Cruze.
 
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