# Car might be overheating, please advise



## MarshmallowD (Aug 11, 2019)

Hello, I am posting this question on behalf of my mother, regarding a 1994 Mazda Miata that she only drives once a week for short errands. The neighbor advised that she idle/run the engine for ten to fifteen minutes every few days to improve the health of the car. Lately she noticed the hood getting very hot during these sessions. The summer heat contributes but she thinks it is still too hot. The meter in the dashboard that gives a hot/cool reading points to just below halfway, after the engine has been idling for a while. When she drives a few minutes down the road for weekly errands the meter's dial will point to just below halfway between hot and cool, also. Is this normal?
She will need to drive a half-hour trip soon and I want to be sure the car is fit to drive that far. Any help is appreciated!


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## de-nagorg (Feb 23, 2014)

Stop, QUIT, running the engine when the car is not moving.

The cooling system relies on moving air through the radiator to cool itself. And the fan cannot compensate for not moving. 

As long as the temp gauge does not register up in the hot range, the car is probably not overheating.

When was the last time that anyone checked the coolant level in the radiator?

And idling in place is not improving the vehicles longevity, if anything it is wearing it out needlessly. 
And could be building up carbon deposits in the combustion chamber.

STOP IT.


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## raylo32 (Nov 25, 2006)

Temps sound normal but as noted above it is best to start it and drive it. Once every couple of weeks is plenty but get it fully up to temp including the oil, so drive it for 20 minutes or so.


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## SPS-1 (Oct 21, 2008)

raylo32 said:


> Temps sound normal but as noted above it is best to start it and drive it. Once every couple of weeks is plenty but get it fully up to temp including the oil, so drive it for 20 minutes or so.


I agree with most of what you wrote, except the time frame. Once every couple of weeks is letting it sit too long in my opinion. Battery can discharge somewhat (some cars discharge faster than others), and bearings and seals can start to dry out. 

I used to have a couple of toys. Tried to at least start them every couple of weeks, but I admit I was pretty bad at keeping to the schedule. Spent a lot of time charging and replacing batteries. I kept one of the cars on a battery tender, but that sure seemed to be overcharging the battery.


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## raylo32 (Nov 25, 2006)

If battery is in good shape and car has no abnormal current drains a couple of weeks is easily OK... at least in my experience. I have done much longer and gotten away with it. But these days I try to put my toys on a tender when they are inactive for more than a few weeks.

This thread just reminded me I need to put the tender back on my motorcycle... or I might be needing to replace the battery prematurely. It has sat for a couple months already since I had hand surgery. But the battery is fairly new and it should be fine. Maybe I'll just take it out for a ride Monday.



SPS-1 said:


> I agree with most of what you wrote, except the time frame. Once every couple of weeks is letting it sit too long in my opinion. Battery can discharge somewhat (some cars discharge faster than others), and bearings and seals can start to dry out.
> 
> I used to have a couple of toys. Tried to at least start them every couple of weeks, but I admit I was pretty bad at keeping to the schedule. Spent a lot of time charging and replacing batteries. I kept one of the cars on a battery tender, but that sure seemed to be overcharging the battery.


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## huesmann (Aug 18, 2011)

The "normal temperature" needle position on the dial is about 11:30 for that era Miata. As long as the needle on the temperature dial does not go past halfway, it's fine.

Miatas come up to operating temperature very quickly.

If the needle ever goes past 11:30 to 12:00 or past, she must immediately stop the car and turn off the engine, because it's overheating.


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## ukrkoz (Dec 31, 2010)

Seriously....




*So… How Long Can I Let My Vehicle Idle?*



_Technically, the answer to this question is – *indefinitely.* We say technically because your car will eventually run out of gas. And it will not idle without gas._
_However, if you let your car idle for as long as there is gas in the tank, you can be sure that your engine will keep running. That is to say; it will keep doing so unless something, such as a thermostat or a fan belt, breaks._
_If all your systems are functioning properly, the engine will heat up to the operating temperature and resume working until you turn it off. Most cars nowadays contain water-cooling systems. *Therefore, it is not necessary for the air to flow into the engine to cool it down.* Your car will not inevitably overheat if left idling._

OP, *under the circumstance of that vehicle being in good working order and temperature sensor functioning well,* your mother is doing NOTHING WRONG. Wasting gas, pretty much, but that's her money.


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## Bondo (Dec 8, 2007)

> Lately she noticed the hood getting very hot during these sessions.


Ayuh,..... Of course it gets hot to touch,.....

Normal operatin' temps of motors is 180* to 200*,......

100* is *HOT* to touch,......

I agree with the other posters,.... idlin' the car does more harm than good,....


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## Dave Sal (Dec 20, 2012)

For a vehicle not driven daily, it's a good idea to use a battery tender. When I was working I had a company car for work so I'd rive my personal car a couple days a week and found that my battery was dead after a couple years from buying the car new. Replaced the battery and bought a tender, and this battery lasted over eight years. My current battery is about nine years old and still running strong, as I use my battery tender every other week during summer and weekly during the winter.


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## Bigplanz (Apr 10, 2009)

I have a scanner that records coolant temp, cylinder head temp and transmissin fluid temp. 

My normal readings, after driving on the interstate are coolant temp 190, cylinder head 212, transmission 174. 

Needle gaages on the dash are not very precise, but if it is in the middle, and the gauge is working, it isn't overheating. A scanner that reads real time coolant temp will answer your question. This normal reading varies from model to model. My windstar is reading normal with a coolant temp of 204, for example. Fan kicks on and it drops back to 195. My Navigator hits 195 and then drops back to 188-190.

Idling for long periods is harder on an engine than interstate driving. The engine runs better under load than idling.


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## lenaitch (Feb 10, 2014)

Agree with pretty much all of above. So long as all the bits of the cooling system are operating properly it is probably fine. A subjective 'it seems hot' is of little value. All of the heat generated by the engine and radiator has few places to escape and simply rises in the engine compartment. If the gauge is in showing in the 'normal' range I wouldn't worry about it, but she should consider when the last time she had the coolant replaced.


Agree that she is wasting money with all that idling and doing absolutely no good to the engine.


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## Brainbucket (Mar 30, 2015)

Vehicles can run all day, idling. I do this at my shop looking for overheating. If it's overheating, setting here idling usually makes it rear it's ugly head. All vehicles should be normal idling all day with no harm. That's what fans are for. As long as the temp gauge is within normal range, your good. She doesn't know what normal is on her gauge means she hasn't looked at it. Just jump in and drive. :vs_cool:


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## fireguy (May 3, 2007)

Sounds like your mother just drives the car. So, nobody is checking oil, antifreeze, w/s wiper fluid and such. It is time to take the car to a shop and have all the fluids checked, tires checked, wiper blades checked. How many miles is the car driven? 

At a Chevy dealership where I worked, we had a lady like your mother. Twice a year she drove the car to a town about 25 miles away. Each time, she had the car checked for problems. We smiled, put the car on the rack and checked all the fluids, tires, changed the oil and filters as needed. We then washed and delivered the car. We did not make much on her, but we got all her family business. More importantly, we knew her car was safe for her very limited use. Unfortunatly, not all of the dealers I worked in had those high ethics.


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## huesmann (Aug 18, 2011)

Brainbucket said:


> She doesn't know what normal is on her gauge means she hasn't looked at it. Just jump in and drive. :vs_cool:


Mom may not know what normal is, but I told the OP what it is, and based on what he says, it runs at normal temp.


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## u3b3rg33k (Jul 17, 2018)

de-nagorg said:


> Stop, QUIT, running the engine when the car is not moving.
> 
> The cooling system relies on moving air through the radiator to cool itself. And *the fan cannot compensate for not moving. *
> 
> ...


WRONG! That's literally why the car has a fan. he's not talking about doing 6 dyno pulls in his mom's garage. he's talking about idling. 

seriously, OP appears to know some ignorant folks, but leave the FUD at home ok?


honestly if the car is really ONLY driven for short trips, getting it to operating temp PRIOR to driving it might not be so bad. best case would be the occasional highway trip.


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## huesmann (Aug 18, 2011)

As I said before, unless the store is right next door, or it's winter, the car will get up to operating temp by the time mom reaches the store.


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## MarshmallowD (Aug 11, 2019)

Thanks to everyone who posted a response!


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## carmusic (Oct 11, 2011)

stop idling for nothing and make a 3-4 hours trip at least once a year


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