My radiator got a leakage so I made a direct connection to the fan from the battery i.e. irrespective of the engine temperature the fan would start as soon as you turn on the ignition switch on. It worked fine in summers but in winters the gauge indication barely goes pass the "C" mark.

I think for engine to run smoothly there has to be a normal operating temperature which is usually indicated by the middle point of "C" and "H". I haven't observed it but I think the fan used to turn on when the needle would go past this middle point.

Should I be worried about this or is "the cooler the better"??

EDIT: thanks for the responses, but I meant the normal "operating temperature INDICATION". Because I cant measure the temperature. Is the operating temperature, people mentioned in the responses, indicated when the needle is exactly in the middle, a lil below that or where?

  • The engine is optimised for a paticular temp .Running to cold affects wear and economy and smoothness .This temp may vary for different engines but 70 celcius would be not too bad .
    – Autistic
    Commented Feb 8, 2016 at 10:00
  • It should always eventually reach the middle point, cold isn't as bad as hot, but still bad. If it doesn't in winter - check your thermostat. Commented Feb 8, 2016 at 10:10

2 Answers 2


Optimal engine temperature is about 190-210. Running cold leads to higher fuel consumption and increased wear. You want the engine temperature to be at least 165* F (~74* C).

Rather than having the fan run 100% of the time, it would be better to have it connected to a switch inside the cabin. This way you can turn it on once the temperature starts to get high, and switch it off once it drops. Make sure to put a fuse on there near the battery in case anything shorts.

Check your coolant level. If your temperature sender isn't submerged, it will read low (if it reads at all).

As "I have no idea what I'm doing" said, check/replace your thermostat if the other 2 solutions do not work.

Another note. Since you have a leak, you may be tempted to add water to your cooling system rather than a proper coolant mix. This is dangerous for 2 reasons - the freezing point is higher, and the boiling point is lower. There are 2 ways you increase the boiling point - mix with coolant and build pressure in your cooling system. Most cooling systems can handle 16psi. The boiling point is increased 3*F per pound of pressure. If you have a leak, you will not be able to achieve this and your boiling over point will be lower.

  • I meant the "indication" mainly, not the actual temperature, because no way I can know the exact temperature of my engine.
    – shabby
    Commented Jun 14, 2018 at 5:57

The answer with the 190-210 degrees Fahrenheit is good. Mechanics have a pretty straight forward term for that. It's called operating temperature. It's intresting that the temperature range or operating temperature is 190-210F. To answer your question, yes, it's BAD! for your engine to run cold. It is crucial to have your cooling system work properly. As well as ALL the other systems in a machine. Sure you can use the machine and it will do it's job, but it will fail prematurely. I highly recommend making repairs to your vehicle before other or more permanent failures occur. And just to point out just how important the cooling system is! Not only does it maintain operating temperature, but it also helps or assists the engine reach operating temperature quicker. Simply because the coolant (50% water 50% ethylene glycol or propylene glycol, sometimes 60/40. Depending on the climate you live in) heats up faster and maintains the heat more efficiently. In fact, only the coolant that's at the engine does that. The rest of the system is on stand by untill the engine gets to 185F. The valves that block the passage of coolant from and too the engine begin to open. At 190n5F they are fully open. ...IT'S BAD TO RUN A COLD ENGINE. There is s term for that too, severe driving. When you drive for 5 to 10 min, or short distances.

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