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When you come back from a drive and it’s hot out, and you pull into the garage or driveway, if your high speed fan is on and the engine temp is up there, do you let it idle to cool down or just shut it down? At first I was letting it idle while the high speed fan ran to cool it down and once the high speed fan shut off, I would turn it off. But sometimes it could take 5-10 minutes to cool down enough that the high speed fan turns off. I definitely pop the hood and open it up to let the hot air escape.
Am I overthinking this? Thoughts?
Thinking about a Haibeck chip just for the high speed fan setting change from factory.
That being said is the Haibeck chip worth the price of admission?
Do you think the fan is producing the same airflow across the radiator to cool it off as driving it would?
Why not just get yourself a big fan and blow it in front of the car and the open engine bay?
And yes, I think you are way over thinking this and searching for a solution to a problem that doesn't exist.
Of course the chip is a great addition, and it will assist as described with the fans and much more.
If you were driving in the desert your thought of cool off procedure certainly would help.
Here in the Philadelphia region, even on a 100 degree day like today, it might prove helpful, but not needed.
If you are running with the AC on, both fans are active even below 228.
Given that, just cruise lightly on your way home and let the fans cool it down for you.
I mostly ignore the gauge and keep the display on coolant temp as it is far more accurate.
you might reduce your homes electrical usage by cooling it off so as to not overheat your garage, but unless your temps are way elevated, you are pursuing a solution that would be good in terms of lower heat soak, but nowhere near beyond the designed tolerance.
Far more fun to drive it at high speed with air pushing through rapidly with the fans and the resultant grin on your face......................
Marty
I personally, do have a habit of allowing vehicles to cool down a bit before shutting off as there can be a temp spike in localized areas before cooling off occurs.
On my vehicles with electrical fans I will let it idle typically until it reaches the lower set point or close to for shut off. If I have been ******* on the the Charger, which has a liquid to liquid oil cooler and oil temps are high I will let it idle and cool down oil temps first (which cause higher coolant temps first) and then once oil reaches equilibrium with coolant temp I let coolant drop with fans as much before shutting off.
With clutch fans, I typically will bring the rpms off idle a bit to move additional air. On my 94 Chevy 2500 this will drop the temp quite a bit and once the gauge bottoms out on it's ability to shed the heat I shut it off then. (Typically close to min. T-stat flow)
I find it interesting that my dd, when it warms up, the needle on the dash stays put right in the middle. But the vettes, the needle varies. Why is that?
On my c5z, I let it idle if it’s hot and it cools down a lot quicker than the zr-1. The zr-1 takes forever.
I find it interesting that my dd, when it warms up, the needle on the dash stays put right in the middle. But the vettes, the needle varies. Why is that?
On my c5z, I let it idle if it’s hot and it cools down a lot quicker than the zr-1. The zr-1 takes forever.
Make sure your fans are working properly. Rad clean. The later cars have two speed fans. My cool down times when fan on are fast just a few minuets. Another reason to get Marc's chip as it turns on both fans for fast cool down. " Both of the cooling fans are turned on at 205 degrees. Both are turned off at 200 degrees." 210 is the most I have ever seen. One other thing I had a 93 that ran fine at speed but in traffic would stay at the hotter end. The thermostat was not opening completely.
The clean radiator admonition is important. Many times a cooling problem n a C4 ZR-1 is due to a radiator that has picked up years of leaves, dirt and debris. As everyone knows, the C4s are bottom feeders; than is, they pick up cooling air from very close to the ground. I had some overheating on my '93 many years ago and when my mechanic removed the radiator the cooling fins were about 40% blocked with road debris. He hosed it out and all was fine. I remember Marc Haibeck once saying that he got about ten pounds of leaves, sand and other junk out of one radiator. I also had Marc install one of his debris screens made from 1/4" hardware cloth (mesh screen). While it does reduce air flow slightly, it keeps leaves and other stuff from getting to the radiator. Never had a cooling problem after that. --Bob
I don't want to start any wars but I have a quick question. Other than you THINK you are doing something beneficial, do any of you have any real objective evidence that you are actually accomplishing anything by letting the car idle for a while to help it cool down a few minutes faster, or opening the hood to let heat escape? I have been driving all kinds of cars from Chevys, Fords, Vettes, Porsches, BMWs, Fiats, VWs, trucks, motorcycles, golfcarts, and many, many others for the past 48 years, and when I am done driving, I turn them off and get out of the car. No prolonged idling, no opening of the hood to let heat out, nothing, just turn it off and get out. I have never seen any deleterious effects from this nor have I ever heard of any from the many thousands of people I know who own and drive cars. Sorry, but this is all a bunch of nonsense unless at least one of you can prove me wrong with some observable proven benefit to doing any of this. Like I said you are trying to solve a problem that doesn't exist. Does any manufacturer or car guru tell you or recommend this practice, and what is it supposed to do, other than getting the car to ambient temp a few min. faster?
I agree with @mrlmd . There is no need to cool down prior to shutting off the engine. I never do and nothing bad has happened. Ride 'em hard and put 'em away wet.
Just with a quick Google search.... "Is there a benefit to idling down a hot engine?"
Yes, there is a major benefit to idling down a hot engine, but it primarily applies to turbocharged vehicles or engines that have just been working under extreme, heavy loads. Letting a hot engine idle for 1 to 3 minutes before turning it off allows heat to dissipate safely.
Key Benefits of Idling Down a Hot Engine
Prevents Turbo Oil Coking: Turbochargers spin at incredibly high speeds and get extremely hot. If you shut off the engine immediately after hard driving, the oil pump stops. The stagnant oil left inside the blazing-hot turbo will literally bake ("cake" or "coke"), turning into destructive carbon sludge that ruins turbo bearings.
Avoids "Heat Soak": When an engine is running, the water pump and radiator fan actively move coolant to reject heat. Abruptly stopping the engine cuts off this circulation. The residual heat trapped in the heavy metal components radiates outward into the stationary coolant and plastic parts, causing a massive spike in temperatures under the hood.
Prevents Engine Warping: Idling stabilizes the transition from high-load operating temperatures down to a normal thermal equilibrium. This controlled cooling prevents sudden, uneven metal contraction, which can warp cylinder heads or trigger head gasket failures.
Prevents Fuel Vapor Lock / Backfiring: On some older or carbureted machinery, shutting down a scorching engine can boil the fuel in the delivery lines or cause unburnt fuel to detonate in the exhaust pipe (backfiring).
When Is It Actually Necessary?
Always Necessary: After towing heavy loads, driving up steep mountain passes, high-speed highway driving, or racing on a track. [
Rarely Necessary: During normal daily commuting, running errands, or driving slowly through a neighborhood right before parking. The slow driving acts as a natural cooldown period.
Modern Car Exceptions: Many modern passenger vehicles feature electric water pumps or auxiliary cooling fans that continue running automatically after you turn the key off, mitigating the need to manually idle the vehicle.
No turbos on my cars. I get the need to cool down from a hard run but I don't drive aggressively on the small streets near my house. The last few blocks therefore are the cooldown lap. I pull in the drive and shut down.
No I don’t think I was trying to solve a problem that wasn’t there. Just having a discussion with other zr-1 guys with varying opinions…that’s what the forum is all about.
Never thought about the thermostat maybe not opening fully or slowly. It’s probably the original tstat if I had to guess based on the rest of the car. Will also check the front radiator area.
I did notice a small drip that second to last time I drove it…and it was hot. Then last time, after the drip, it was hot again but no drip. But did notice after full cool down, next day really, the coolant dipstick in the front reservoir wasn’t at the full cold mark anymore. Wasn’t even registering on the stick anymore. But there is coolant in the reservoir tank.
I’m assuming adding coolant would only be done at the front plastic reservoir tank until the cold mark is met? There is no need to open the radiator cap on the main black tank near the cowl?
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Cool Down After Driving
