Is it normal for the temp gauge to go past half way slightly ? Watch

Cleverboy1991
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I've owned this car for about 6 months, It is a 2007 ( 57 ) Vauxhall Vectra C 1.9 CDTI.

Anytime the car is slow moving such as in rush hour or when I'm driving slowly through traffic or the Safari Park, e.t.c. the temp gauge needle goes about 1 - 2 mm past the half way line.

I've been told on some forums that this is normal by the majority of the people there, however I have never witnessed this on any of my previous cars.


The temp gauge usually stays well below half way in steady traffic and is always well below half, but as soon as I hit slow moving traffic the needle goes 1 - 2 mm above half way.


So is this normal ? could it be the thermostat ? ( if it was then would it be doing this in all driving conditions ? ) .

thanks
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IWMTom
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(Original post by Cleverboy1991)
I've owned this car for about 6 months, It is a 2007 ( 57 ) Vauxhall Vectra C 1.9 CDTI.

Anytime the car is slow moving such as in rush hour or when I'm driving slowly through traffic or the Safari Park, e.t.c. them temp gauge needle goes about 1 - 2 mm past the half way line.

I've been told on some forums that this is normal by the majority of the people there, however I have never witnessed this on any of my previous cars.


The temp gauge usually stays well below half way in steady traffic and is always well below half, but as soon as I hit slow moving traffic the needle goes 1 - 2 mm above half way.


So is this normal ? could it be the thermostat ? ( though if it was I guess it would be faulty reading on the gauge in all driving conditions ? ) .

thanks
Is it in the red at all? If not, it's within normal operating parameters.
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Cleverboy1991
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(Original post by IWMTom)
Is it in the red at all? If not, it's within normal operating parameters.
Nope, but it is above half, and I always considered below half as safe and above half as too hot.

Is it supposed to go above half way on these cars or is it a faulty thermostat or something ??

The only time e the temp ever went above half on any of my previous cars was usually when it had a leak or other problems
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IWMTom
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(Original post by Cleverboy1991)
Nope, but it is above half, and I always considered below half as safe and above half as too hot.

Is it supposed to go above half way on these cars or is it a faulty thermostat or something ??

The only time e the temp ever went above half on any of my previous cars was usually when it had a leak or other problems
I'm sure it's fine... it's not showing as dangerously warm or anything.
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Cleverboy1991
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(Original post by IWMTom)
I'm sure it's fine... it's not showing as dangerously warm or anything.
Thanks, but I've spend thousands of pounds in my 5 years of driving on engine repairs on previous cars, so just want to be sure.

Even if it is okay I'm just wondering if all other cars the same model do the same, if it's just a common fault or if it is something that can be replaced to solve it ?

I'd like my engine to be as cool as possible at all times within reason,
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IWMTom
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(Original post by Cleverboy1991)
Thanks, but I've spend thousands of pounds in my 5 years of driving on engine repairs on previous cars, so just want to be sure.

Even if it is okay I'm just wondering if all other cars the same model do the same, if it's just a common fault or if it is something that can be replaced to solve it ?

I'd like my engine to be as cool as possible at all times within reason,
You should probably look for a owner's club somewhere on the internet as you're more likely to get more relevant responses.
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Cleverboy1991
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(Original post by IWMTom)
You should probably look for a owner's club somewhere on the internet as you're more likely to get more relevant responses.
I was but I keep getting banned because apparently I ask to many questions, the reason for my ban was trolling, wtf ?!

I did do this question before being banned and had mixed responses that it's normal for this to happen, but then other replies saying it isn't
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IWMTom
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(Original post by Cleverboy1991)
I was but I keep getting banned because apparently I ask to many questions, the reason for my ban was trolling, wtf ?!

I did do this question before being banned and had mixed responses that it's normal for this to happen, but then other replies saying it isn't
When did you last change your oil?
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RoyalSheepy
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(Original post by Cleverboy1991)
I've owned this car for about 6 months, It is a 2007 ( 57 ) Vauxhall Vectra C 1.9 CDTI.

Anytime the car is slow moving such as in rush hour or when I'm driving slowly through traffic or the Safari Park, e.t.c. the temp gauge needle goes about 1 - 2 mm past the half way line.

I've been told on some forums that this is normal by the majority of the people there, however I have never witnessed this on any of my previous cars.


The temp gauge usually stays well below half way in steady traffic and is always well below half, but as soon as I hit slow moving traffic the needle goes 1 - 2 mm above half way.


So is this normal ? could it be the thermostat ? ( if it was then would it be doing this in all driving conditions ? ) .

thanks
I shouldn't think there was a problem until it exceeds that point and moves into the red. Have you just noticed this?
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Nuffles
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I'd check your radiator to see if any of the fins are blocked or missing. Diesels run colder than petrols by nature and saloons/estates are often fitted with decent sized radiators from the factory so they can tow things like caravans on hot days easily, so it's rare for the thermostat to not be able to keep the system running at "half way", not that it means much as the gauge is just there to make you feel better rather than to display anything meaningful.

Your car running at a little over half isn't cause for concern, but I would be looking at parts of the cars cooling system to make sure everything was up to scratch. Take a look at the radiator first off, as that's easiest. I'd probably replace the thermostat as well as they're cheap and usually pretty easy to replace - it'd be good to flush your coolant at the same time too. It could be the water pump failing, but that's very unlikely.
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Sweyn Forkbeard
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(Original post by Cleverboy1991)
I was but I keep getting banned because apparently I ask to many questions, the reason for my ban was trolling, wtf ?!

I did do this question before being banned and had mixed responses that it's normal for this to happen, but then other replies saying it isn't
If you're really concerned you could get a Bluetooth OBDII adapter (cheap ones for under £10 on Amazon) and get the Torque app on Android (not sure if there's an iOS version).

Once you get it connected up and configured you can get real-time coolant temperature data.
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weatherman12
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check the coolant level. Once up to operating temperature it should remain fairly constant temp
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GonvilleBromhead
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(Original post by Cleverboy1991)
I've owned this car for about 6 months, It is a 2007 ( 57 ) Vauxhall Vectra C 1.9 CDTI.

Anytime the car is slow moving such as in rush hour or when I'm driving slowly through traffic or the Safari Park, e.t.c. the temp gauge needle goes about 1 - 2 mm past the half way line.

I've been told on some forums that this is normal by the majority of the people there, however I have never witnessed this on any of my previous cars.


The temp gauge usually stays well below half way in steady traffic and is always well below half, but as soon as I hit slow moving traffic the needle goes 1 - 2 mm above half way.


So is this normal ? could it be the thermostat ? ( if it was then would it be doing this in all driving conditions ? ) .

thanks
Diesels do run slightly colder, but around half is fairly standard on every car I've owned. The gauge doesn't have useful information, that's why a lot of cars don't even bother putting temperature range on them. If the car is overheating most modern ECUs will either modulate (read put the car in limp mode and demand you stop) or at the very least start throwing error codes and light the dash up like a christmas tree.

Bear in mind combustion, even of diesel, causes a hell of a lot of thermal energy. Cars run HOT.
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CurlyBen
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If your car is sitting at higher temperatures when moving slowly, the obvious thing to check is the cooling fan. Having said that, slightly over halfway wouldn't worry me at all. The gauge isn't precisely calibrated, so small variations in the sender and gauge will lead to some change in where the needle sits for the same temperature. Variations in the thermostat will also lead to changes in the exact temperature it holds. Thermostats, water pumps, bad radiators and coolant levels are unlikely to be at the root of temperature variation at different speeds - if there is sufficient cooling capacity at high speeds then there should be no issues when at idle or just above, provided there's sufficient airflow over the radiator.

You really don't want to run the engine as cold as possible at all times. Cold engines suffer significantly more wear, because the clearance between moving parts is tighter and you also have issues such as fuel condensation on the cylinder walls. What you want is the engine to reach its designed operating temperature as quickly as possible and then stay there. If it was really bothering you that much you could change the thermostat for one that opens at a lower temperature. Personally, I'd potentially be more concerned at the low temps you're seeing, not the high temps.

As a side note, I disagree with Nuffles and GonvilleBromhead saying the gauge doesn't show anything useful. It's very useful to see the rate of change, or just to see abnormal indications. I've been having problems with the cooling system on my car, and I know exactly where the needle should be. If it rises above that I know immediately that something isn't right, but if I can't stop immediately I set the blowers to max hot and then I can watch what effect that's having. Sometimes it's enough to stabilise the temperature at an elevated level until I get home, sometimes it isn't. Sometimes the air bubble will bleed itself and the temperature will drop right back to where it should be and I can turn the blowers off. In each situation I can prevent it ever reaching red line temperatures. A simple light wouldn't let me know anything was wrong until I was already at the red line and I'd have to pull over immediately.

If that's still not enough of a reason to have a gauge, on one occasion I had a coolant hose develop a pinhole leak when I was 7,000' up a volcano. I noticed the gauge was climbing and patched things up before losing too much coolant, so I was able nurse the car 50 miles back to the city where I could get a new hose. If I'd had no indication of a problem before the red line was reached I would probably have had to have the car recovered, at a cost of a few hundred dollars. Gauges are great, if you monitor them.
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Joinedup
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The thermostat and fan are designed to keep the engine coolant between an acceptable max and min value while the engine is running, the acceptable range is narrower than the distance between the blue and red lines on a gauge and tbh you might not notice the needle moving

... it sounds like the correct working of that system is what the gauge is showing you. I'd guess the gauge is just slightly more responsive than the one in your previous cars.
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Nuffles
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(Original post by CurlyBen)
If your car is sitting at higher temperatures when moving slowly, the obvious thing to check is the cooling fan. Having said that, slightly over halfway wouldn't worry me at all. The gauge isn't precisely calibrated, so small variations in the sender and gauge will lead to some change in where the needle sits for the same temperature. Variations in the thermostat will also lead to changes in the exact temperature it holds. Thermostats, water pumps, bad radiators and coolant levels are unlikely to be at the root of temperature variation at different speeds - if there is sufficient cooling capacity at high speeds then there should be no issues when at idle or just above, provided there's sufficient airflow over the radiator.

You really don't want to run the engine as cold as possible at all times. Cold engines suffer significantly more wear, because the clearance between moving parts is tighter and you also have issues such as fuel condensation on the cylinder walls. What you want is the engine to reach its designed operating temperature as quickly as possible and then stay there. If it was really bothering you that much you could change the thermostat for one that opens at a lower temperature. Personally, I'd potentially be more concerned at the low temps you're seeing, not the high temps.

As a side note, I disagree with Nuffles and GonvilleBromhead saying the gauge doesn't show anything useful. It's very useful to see the rate of change, or just to see abnormal indications. I've been having problems with the cooling system on my car, and I know exactly where the needle should be. If it rises above that I know immediately that something isn't right, but if I can't stop immediately I set the blowers to max hot and then I can watch what effect that's having. Sometimes it's enough to stabilise the temperature at an elevated level until I get home, sometimes it isn't. Sometimes the air bubble will bleed itself and the temperature will drop right back to where it should be and I can turn the blowers off. In each situation I can prevent it ever reaching red line temperatures. A simple light wouldn't let me know anything was wrong until I was already at the red line and I'd have to pull over immediately.

If that's still not enough of a reason to have a gauge, on one occasion I had a coolant hose develop a pinhole leak when I was 7,000' up a volcano. I noticed the gauge was climbing and patched things up before losing too much coolant, so I was able nurse the car 50 miles back to the city where I could get a new hose. If I'd had no indication of a problem before the red line was reached I would probably have had to have the car recovered, at a cost of a few hundred dollars. Gauges are great, if you monitor them.
My point was that the gauges aren't calibrated properly and don't really show anything useful other than that the engine is running at roughly the right temperature. Far more useful would be a properly calibrated gauge, but that would never really sit slap bang in the middle and would fluctuate depending on air temp, engine load, and a load of other variables. Apparently 99% of people prefer a gauge that jumps straight to the middle and only deviates when there's something seriously wrong with the engine temps.

They're useful enough to tell you when something's seriously wrong, but don't really give you any kind of accurate information.

The gauge on my TDI Passat has read ever so slightly cool ever since I bought it, regardless of weather conditions or load (didn't even budge hauling ass up a steep hill in sixth gear with five guys and luggage on board, towing a trailer). Recently it decided to read bang on the middle for a few weeks, before going back to reading slightly cool. A proper coolant temp gauge would be cool, but seeing as it's a diesel an EGT gauge would probably be more useful.
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CurlyBen
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(Original post by Nuffles)
My point was that the gauges aren't calibrated properly and don't really show anything useful other than that the engine is running at roughly the right temperature.
It's not calibrated, but the repeatability should still be good. That means that if the needle is in the same place the temperature is the same (within the limit of the sensitivity of the system). You don't know precisely what that temperature is, but that's less useful than knowing it's running at its normal temperature.

Far more useful would be a properly calibrated gauge, but that would never really sit slap bang in the middle and would fluctuate depending on air temp, engine load, and a load of other variables.
No, it wouldn't! The job of the thermostat is to regulate the coolant flow to maintain the desired temperature. Once it's reached that temperature it should stay there until you reach the maximum capacity of the cooling system. The fluctuation should be in the flow of coolant to the radiator, not the temperature.

They're useful enough to tell you when something's seriously wrong, but don't really give you any kind of accurate information.
Accurate isn't the same as calibrated. The aircraft I fly have 'calibrated' gauges for oil and cylinder head temps but there's still variation between aircraft under the same conditions, and to be honest all I really care about is whether it's different from normal for that engine.

Watching the way the coolant temp gauge on my car behaves gives me a pretty good idea what's going on with the cooling system. A few examples:

- if the gauge takes a long time to rise or never reaches the middle, that suggests the thermostat is stuck open

- if it rises quickly beyond its normal middle mark that suggests lack of circulation (thermostat stuck, air lock or coolant loss)
- if you put the blower on max hot and the gauge starts to fall, that tends to point to a stuck thermostat or relatively minor coolant loss. If it has no effect and you get cold air out of the blower that suggests air lock or significant coolant loss

- if it rises slowly above the middle and stabilises that suggests insufficient cooling capacity (heavy load, inadequate airflow or cooling system in poor repair)
- on Fords, if not on other cars, putting the AC on max automatically turns the engine fan on if the speed is below 40mph, which is an easy way to check the fan. Additionally, if the AC cycles on and off, especially when stationary, that points to inadequate airflow

You can probably tell I've had numerous cooling issues! But I'm not sure knowing exact temperature would help in any of those cases - rate of change would be much more useful.


The gauge on my TDI Passat has read ever so slightly cool ever since I bought it, regardless of weather conditions or load (didn't even budge hauling ass up a steep hill in sixth gear with five guys and luggage on board, towing a trailer). Recently it decided to read bang on the middle for a few weeks, before going back to reading slightly cool.
My first thought would be to look at the voltage regulator. You can also normally read coolant temperature with an OBD II reader, which should let you know if it is actually a variation in coolant temperature. As for going up that hill, that just means you didn't reach the cooling system's capacity or, if you did, you didn't for long enough to cause a detectable rise in the coolant temperature.

By the way I don't dispute that manufacturers design a system that will tend to sit rock solid in the middle, but that's down to the sensitivity rather than the accuracy or calibration of the gauge. And to an extent it makes sense - people like to see the same thing every time they drive the car.


A proper coolant temp gauge would be cool, but seeing as it's a diesel an EGT gauge would probably be more useful.
I'd actually argue that's a gauge will only really tell you if something's going wrong. It will give an indication of power, but then your right boot will do that as well. It's going to vary far more than the coolant temperature will.

(Hopefully it's obvious, but I'm not trying to knock your opinion - just saying why I don't agree)
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StanC
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Engines run better when warm. Just replaced my thermostat and temp sensor on 05 Zafira 1.8 and temp runs just below half way up scale so just below 90c . Fan kicks in when idling just a little above this. I replaced components as temperature on gauge was near bottom when driving and only rose to 90c when idling at which time fan kicked in and temp was stable, as soon as I drove any distance temp gauge dropped back to cold. Solution Thermostat and Temp Sensor replaced. Buy complete unit and only takes less than an hour for DIY to change.
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Mechanic Lucario
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It really depends, if it moves a little bit, then it could be a open thermostat, a small open in the thermostat, but usually won't cause damage, and two, the age of your car. If it's a 75-86 then it's really old, cars in the 50s, 60s, and 70s, the thermostat gauge was controlled by a steel cable (Like you see the one on the throttle cable) so if that cable gets old, then it can erode and cause it to snap, which will make it go above normal, but legit, if it ain't overheating, then don't worry about it. It might also be a worn out electrical connection inside the gauge, and yes if it was the thermostat then it will continuously creep towards the HOT area. But no it ain't a thermostat problem, it's either normal or an electrical (Shorted Circuit) problem. Like I said, if it doesn't overheat, then you'll be fine
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