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Engine Temperature needle

Just asking for a bit of peace of mind. Only had my 147 for a week, and its going great. One thing though, the engine temp needle in the dash seems to have a bit of movement in it. Other cars I have had normally sit at one temp. The 147 varys a bit, it never goes much higher than 90 but just never sits constant. Is this normal?

Its not a water pump prob is it??!!

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Re: Engine Temperature needle

As long as it isn't dropping too far below 90 or rising too far above 90 it is fine.
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Re: Engine Temperature needle

As the climate control system makes demand of the heat from the engine then the temperature gauge may drop a little. And vice versa.
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Re: Engine Temperature needle

Thats normal, it happens on mine as well. It never goes above 90 and when traveling depending on weather conditions then it can drop 5-10 degrees less.
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Re: Engine Temperature needle

i only have my 156 about a week and a half,just after i bought it i noticed the temp gauge dropped right off when i was driving and sat just above 90 when stationary so i changed the thermostat (myself bit tricky to get at but straight forward)which fixed the problem but temp gauge does same as yours,can sit just above 90 until fan kicks in or your driving and goes up and down slightly depending on whether your moving or stationary.try bringing car up to temp and watching the gauge while parked when it creeps just over the 90 mark check your cooling fan comes on and the gauge should drop if it does i'd imagine your good
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Re: Engine Temperature needle

Is it possible that my sensor in the top of the stat has gone?

I changed the thermostat and the car gets sits at 90 in traffic and when on the move it stays at just above 70..

It doesn't make sense.
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Re: Engine Temperature needle

Quote:
Originally Posted by OperationAlfa View Post
Is it possible that my sensor in the top of the stat has gone?

I changed the thermostat and the car gets sits at 90 in traffic and when on the move it stays at just above 70..

It doesn't make sense.

its supposed to do that. i've replaced my rad, thermostat and coolant temp sensor (on top of thermostat) and mine still reads 70-90 during use. its normal. i think people who's temp gauge reads higher constantly must have less effective rads. the 156 rad usually lasts approx 70k but doesnt get changed until it leaks so you can go for years with an ineffective rad.
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Re: Engine Temperature needle

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Originally Posted by jug View Post
its supposed to do that. i've replaced my rad, thermostat and coolant temp sensor (on top of thermostat) and mine still reads 70-90 during use. its normal. i think people who's temp gauge reads higher constantly must have less effective rads. the 156 rad usually lasts approx 70k but doesnt get changed until it leaks so you can go for years with an ineffective rad.
I was to understand it should be nigh on 90 at all times
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Re: Engine Temperature needle

That's quite normal. Mine's exactly the same, sits just about 90 in traffic, otherwise it sits in the 70s when cruising and gradually edges up to 90, before dropping quickly back down to the 70s again. Most of the time that happens pretty fast, it doesn't hang around long at the higher reaches when you're moving freely, so unless you've got your eyes glued on the needle (rather than the road!) it might look as if it's almost always in the 70s. I've had my thermostat and sender changed and it's still behaving the same. It was pretty obvious when the 'stat needed changing as it was running about 10-15 degrees cooler and never getting far above 75.

Just a word of advice: I got my 'stat changed at a main dealer, and they charged a pretty hefty whack, I'd shop around if you ever do need to change it.
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Re: Engine Temperature needle

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Originally Posted by OperationAlfa View Post
I was to understand it should be nigh on 90 at all times
I understood that to be the case as well, my V6 sits at 90 while on the move, maybe just slightly, ever so slightly under 90 (just a needles width under!!) and in traffic it passes 90 and the fan comes on, which eventually knocks off when the car gets back to 90. Petrol engines are at their most efficient around 90, or so I'm told.

My JTD runs cooler, just over 70 normally, but in traffic it can get up to 90. This is with a new temp sender, thermostat and radiator, not sure of the condition of these in the V6 but it appears OK.

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Re: Engine Temperature needle

Mine sits around 75-80 or a little above that when cruising - in traffic it goes up to just over 90 - then the fan cuts in and brings it down to about 75 - 80 again.

Seems there are variations - possibly due to rad condition as suggested above.
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Re: Engine Temperature needle

I'm not quite sure of the actual type of sensor, what it is made of and its construction.

However, I think that it is fair to say that if the sensor itself is defective then its operation will be intermittant. It won't read slightly out...it will tend to read on-off-on-off-on-off etc. It is the connection back to the ECU, the ECU and the calibration data within the ECU that will cause temperature sensor readings to fluctuate more than they should naturally.

Where I work we have a fair few problems with temperature sensor signals and their interpretation.

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Re: Engine Temperature needle

its just an everyday NTC thermistor housed in a brass casing. the varying resistance alters the voltage. if the signal was intermittent it would illuminate the engine management light whenever you lost the signal because the ecu can determine if it is not getting a signal from the coolant temp sensor.

the strange behavior is because the gauge moves so quickly. on most cars the temp gauge is the same as the fuel gauge, they do not respond to small variations in the signal to give a steady reading. on the alfas the temp gauge has traditionally been the type that does show small variations on the gauge. thats not a problem but people who arent used to it get paranoid.

if you consider how a thermostat works you would expct the coolant temperature to fluctuate almost constantly.
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Re: Engine Temperature needle

The switch in the unit is a spring which adjusts with heat to open and close. The sensor is independent as far as I am aware and it sits in the top of the stat itself.

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Re: Engine Temperature needle

Quote:
Originally Posted by OperationAlfa View Post
Is it possible that my sensor in the top of the stat has gone?

I changed the thermostat and the car gets sits at 90 in traffic and when on the move it stays at just above 70..

It doesn't make sense.
On mine, that "70" marks is actually just over 80!
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Re: Engine Temperature needle

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Originally Posted by OperationAlfa View Post
The switch in the unit is a spring which adjusts with heat to open and close.
the spring doesnt adjust, the wax pellet melts at a certain temperature, when that happens the pellet swells forcing the valve open.
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Re: Engine Temperature needle

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Originally Posted by fran156 View Post
That's quite normal. Mine's exactly the same, sits just about 90 in traffic, otherwise it sits in the 70s when cruising and gradually edges up to 90, before dropping quickly back down to the 70s again. Most of the time that happens pretty fast, it doesn't hang around long at the higher reaches when you're moving freely, so unless you've got your eyes glued on the needle (rather than the road!) it might look as if it's almost always in the 70s. I've had my thermostat and sender changed and it's still behaving the same. It was pretty obvious when the 'stat needed changing as it was running about 10-15 degrees cooler and never getting far above 75.

Just a word of advice: I got my 'stat changed at a main dealer, and they charged a pretty hefty whack, I'd shop around if you ever do need to change it.
Changing the stat (depending on model of course) is very straight forward removing the hoses can be a bit tricky because of the factory fitted clips but once you have them off its only 2 bolts holds it on it comes with a new seal already fitted to stat just buy some new jubilee clips because old ones will be unusable and just put it back together refill with coolant and check for leaks/fan kicking in and temp reading i'm not a mechanic but if you have any basic skills its not that difficult try it yourself if you get stuck then call a mechanic just my opinion
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Re: Engine Temperature needle

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Re: Engine Temperature needle

I had my stat done recently - it has been checked as being OK now. The old one was sticking and caked in crud. My car now fluctuates between just over 70 and 90. While moving about 75 seems the norm, and TBH I DO find it a bit disconcerting, however with all the reassurances I get on here I no longer really worry about it. Still - it wasn't getting above 60 before the change of stat, so its an improvement.
now for the squeaky suspension and that sodding airbag light . . . . . .
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Re: Engine Temperature needle

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Originally Posted by jug View Post
its supposed to do that. i've replaced my rad, thermostat and coolant temp sensor (on top of thermostat) and mine still reads 70-90 during use. its normal. i think people who's temp gauge reads higher constantly must have less effective rads. the 156 rad usually lasts approx 70k but doesnt get changed until it leaks so you can go for years with an ineffective rad.
Or a head gasket gone. Becuse when my head gasket went in the 146 the needle sat dead at 90 degrees the whole time. And now that the head is done it is fluctuating like everyone describes and I can set my watch to it when it fluctuates and when it comes to move I know exactly when
 
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