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Is it normal for car engine temperature to go up and down?

I'm aware that in winter cars take longer to reach operating temperature but i've noticed that when it does get there it doesn't stabilise.
Through out journeys the temp gauge will go up and down which seems odd as i'd of thought it would only increase and stablize at the normal operating temp as the mileage of the journey accumulates.

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Reply 1
Original post by chosenone93
I'm aware that in winter cars take longer to reach operating temperature but i've noticed that when it does get there it doesn't stabilise.
Through out journeys the temp gauge will go up and down which seems odd as i'd of thought it would only increase and stablize at the normal operating temp as the mileage of the journey accumulates.

No.
Original post by chosenone93
I'm aware that in winter cars take longer to reach operating temperature but i've noticed that when it does get there it doesn't stabilise.
Through out journeys the temp gauge will go up and down which seems odd as i'd of thought it would only increase and stablize at the normal operating temp as the mileage of the journey accumulates.


Got enough coolant? Is your car still blowing hot air when it's warmed up?

Sounds like a bad sensor to me, but could be something way different. Take it to a garage; the gauge definitely should not fluctuate.
The coolant levels seem fine...so the temperature should not drop at any part of the journey?
Reply 4
Original post by chosenone93
The coolant levels seem fine...so the temperature should not drop at any part of the journey?

Nope.
If it is going up and down real fast then it could be the cylinder head temperature sensor. My previous car had the same problem , I changed that and that solved the problem.
I wouldn't say it's constantly changing but i do notice it will drop at times nothing drastic though. I know nothing about cars but if the temperature is only meant to rise then i may need to get this checked.
(edited 5 years ago)
Reply 7
Original post by Cleverboy1991
If it is going up and down real fast then it could be the cylinder head temperature sensor. My previous car had the same problem , I changed that and that solved the problem.


Have you fixed your brakes yet?

Original post by chosenone93
I wouldn't say it's constantly changing but i do notice it will drop at times nothing drastic thong. I know nothing about cars but if the temperature is only meant to rise then i may need to get this checked.


It's not "only meant to rise". It should rise to a stable point and pretty much stay there.
Original post by Doonesbury
Have you fixed your brakes yet?



It's not "only meant to rise". It should rise to a stable point and pretty much stay there.

So it's normal to drop at times then? The obvious goal is to get it to it's normal operating temperature which it did eventually after an hour and a half but it did drop slightly after about 20 mins the other day so i'm wondering if it's because it was fairly cold outside or something actually wrong.
Reply 9
Original post by chosenone93
So it's normal to drop at times then? The obvious goal is to get it to it's normal operating temperature which it did eventually after an hour and a half but it did drop slightly after about 20 mins the other day so i'm wondering if it's because it was fairly cold outside or something actually wrong.


I didn't say that... I said it should rise to a stable temperature and stay there.

It probably depends on how much it's dropped by and what the exact driving conditions were (and if they suddenly changed after 20 mins). I'd keep an eye on it and if it continues to worry you get it seen too.

How old is the car? When was it last MOT'd? When was it last serviced?
Original post by chosenone93
So it's normal to drop at times then? The obvious goal is to get it to it's normal operating temperature which it did eventually after an hour and a half but it did drop slightly after about 20 mins the other day so i'm wondering if it's because it was fairly cold outside or something actually wrong.

It takes an hour and a half for your engine to get to normal temperature? (I'm assuming by normal temperature, you mean about halfway on the gauge?) That is a LONG time for your engine to be warming up, it should be taking only around 10-15 minutes.
Original post by Doonesbury
I didn't say that... I said it should rise to a stable temperature and stay there.

It probably depends on how much it's dropped by and what the exact driving conditions were (and if they suddenly changed after 20 mins). I'd keep an eye on it and if it continues to worry you get it seen too.

How old is the car? When was it last MOT'd? When was it last serviced?

What i actually meant to ask is if it should only be rising and not decreasing until it's reached its normal operating temperature where it should stablise. At times its gotten there and dropped slightly after some time maybe 20 mins. It's a used car 2006 registration date and was MOT'D in November and seviced in December no issues just wondered what was normal.
Original post by julietlima3
It takes an hour and a half for your engine to get to normal temperature? (I'm assuming by normal temperature, you mean about halfway on the gauge?) That is a LONG time for your engine to be warming up, it should be taking only around 10-15 minutes.

It was particularly cold last week with all the snow but i'll keep an eye on it this week as its gonna be fairly mild.
I can't envision any climate where it can be considered normal for an engine to take that long to warm up.
Reply 13
I'm putting my money on a duff thermostat.
Original post by chosenone93
What i actually meant to ask is if it should only be rising and not decreasing until it's reached its normal operating temperature where it should stablise. At times its gotten there and dropped slightly after some time maybe 20 mins. It's a used car 2006 registration date and was MOT'D in November and seviced in December no issues just wondered what was normal.

It was particularly cold last week with all the snow but i'll keep an eye on it this week as its gonna be fairly mild.


If the engine is continuously on, the temperature should only go up until optimum temp. I bet you it's a faulty sensor.
Original post by IWMTom
I'm putting my money on a duff thermostat.

Good for you. Have a medal
Reply 16
Original post by Cleverboy1991
Good for you. Have a medal

Have you fixed the deathtrap you broke again, yet?
Reply 17
Original post by Cleverboy1991
Good for you. Have a medal


Original post by Doonesbury
Have you fixed your brakes yet?


So, have you?

Original post by IWMTom
Have you fixed the deathtrap you broke again, yet?


It's almost as if he's ignoring any advice...
Reply 18
Original post by Doonesbury
It's almost as if he's ignoring any advice...

Why does that not surprise me 🙄
Cleverboy indeed

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