[anish5225]

Hi,
I have been noticing something strange with the engine temperature on my 2009 Optra Magnum Diesel run 70000 KMs. In the past, after diving for ~ 10 mins, the temp gauge used to reach the halfway mark and stay there for as long as i drive.Then on, it will not go above or below this point no matter how long or how hard I drive.

But since the past few weeks, the temperature gauge hardly touches the earlier settling point even if I drive for an hour or two. Only reaches about midway. If I use the AC, the temperature drops a few notches further. Any idea what could be wrong?

Thank You
Anish

[vikram_d]

Coolant thermostat valve is stuck open as it has most likely gone bad and will need replacement.

[saket77]

Vikram is right in my opinion. The coolant thermostat generally remains closed during a cold engine start-off which restricts the flow of coolant in the engine so that the engine warms up and reaches the operating temperature quickly. Now, what has probably happened in your case is that the valve is stuck at the open position which means the coolant is flowing to the engine even during a cold start. This in turn is preventing your engine to reach the operating temperature as quickly as it should.

Regards,
Saket.

[humyum]

I agree with both Vikram and Saket's Diagnosis. Thermostate valve is stuck open, its not letting the engine attain its operating temperature quickly in the morning and neither is it letter the car operate at its running temperature as coolant is flowing in the water jackets all the time.

Get is fixed asap, there will be a drop in mileage because of this.

[anish5225]

Thank you vikram_d, saket77 and humyum for the quick replies. I will sure get this checked ASAP. May I also know if it is a complex process getting this fixed? Like opening up the engine or other complex procedures.

Thanks again

[vikram_d]

No you do not need to open up the engine. The thermostat valve is always placed outside the engine and it's replacement is a relatively simple job.

[Jeroen]

Originally Posted by humyum

I agree with both Vikram and Saket's Diagnosis. Thermostate valve is stuck open, its not letting the engine attain its operating temperature quickly in the morning and neither is it letter the car operate at its running temperature as coolant is flowing in the water jackets all the time.

Get is fixed asap, there will be a drop in mileage because of this.

The mileage is the least of your worries. Having the engine operate below normal operating temperature causes significant wear and tear, notably on the cylinder liners and piston rings. Nothing you can do about it, just get the thermostat replaced asap.

Jeroen

[mayankk]

Originally Posted by Jeroen

The mileage is the least of your worries. Having the engine operate below normal operating temperature causes significant wear and tear, notably on the cylinder liners and piston rings. Nothing you can do about it, just get the thermostat replaced asap.

Jeroen

Oh?
IN winters, on long drives, my fiesta typically runs at 4-5 notches on the guage. Typically its always at 6.
Last I noticed this was in december 2014. As soon as I hit traffic, it used to climb to the normal levels, but during long runs it used to come back down by the same. Is this as bad?

[saket77]

Originally Posted by mayankk

Oh?
IN winters, on long drives, my fiesta typically runs at 4-5 notches on the guage. Typically its always at 6.
Last I noticed this was in december 2014. As soon as I hit traffic, it used to climb to the normal levels, but during long runs it used to come back down by the same. Is this as bad?

During long, high speed runs, the engine is also cooled significantly by the ram air and also due to the fact that the engine generally operates at a lower stress level being at higher gears most of the time (& hence at lower rpm compared to city traffic), you may notice slightly lower temperatures on the highway runs.

Regards,
Saket.

[Jeroen]

Originally Posted by mayankk

Oh?

IN winters, on long drives, my fiesta typically runs at 4-5 notches on the guage. Typically its always at 6.

Last I noticed this was in december 2014. As soon as I hit traffic, it used to climb to the normal levels, but during long runs it used to come back down by the same. Is this as bad?

Not sure how many degrees a notch stands for. But unless the temperature difference between summer and winter are extreme, most modern engines should actually be able to keep the temperature of the cooling liquid fairly stable. Difficult to judge your particular situation, but you might want to check the thermostat as well.

How bad it is, well again, it is a cumulative effect. So the more miles you do with too low a temperature the bigger the nett effect. But is depends on the delta temperature, compared to normal, and the mileage driven. And how you drive, if its all uphill heavy loading on the engine and 20 degrees to cold, that is not good in the long run.

In general if you run too cold that has a bigger effect then running too hot. To a certain degree, of course, you don't want to overheat obviously.

Jeroen

[Abhi_abarth]

Reading all the posts, I have started feeling scared as my palio S10's temp gauge always stays within the 1/4 mark (Image attached)

Usually, what would be the operating temperature for any engine ? Would it vary from car to car ?

[vikram_d]

Originally Posted by Abhi_abarth

Reading all the posts, I have started feeling scared as my palio S10's temp gauge always stays within the 1/4 mark.

If the 1/4th mark has been constant since you bought the car then it is normal. You need to worry only if the needle goes lower or higher by a huge margin.

[Jeroen]

Originally Posted by Abhi_abarth

Reading all the posts, I have started feeling scared as my palio S10's temp gauge always stays within the 1/4 mark (Image attached)



Usually, what would be the operating temperature for any engine ? Would it vary from car to car ?

Check what the manual says. This looks a little low to me.
Jeroen

[rr_zen]

Interesting thread. While the usual concern would be what if the temp gauge shows a lower temp than normal, my concern is how would I even identify this phenomenon in cars that do not have a temp gauge. For eg, the A-Star

[Jeroen]

Originally Posted by rr_zen

Interesting thread. While the usual concern would be what if the temp gauge shows a lower temp than normal, my concern is how would I even identify this phenomenon in cars that do not have a temp gauge. For eg, the A-Star

The short answer is you wouldn't, unfortunately. You can take your own temperature readings now and then, with for instance a Infra red thermomenter, but its not very practical and you would take a considerable number of readings to figure out if anything is wrong.

If the thermostat is really not working at all, you can often tell by checking the flow of the hot and or cold legs of the cooling liquid system. But again, you need to have some experience in what to look and feel for.

Jeroen