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Discussion Starter #1 (Edited)
hi,just bought a 156 1.8 and the prob was temp guage never got off mark while driving but went up in traffic,have replaced stat and it now works but is erratic! could it be dodgy stat or temp sensor fitted inside stat or maybe something else?am new to alfa so any help appreciated:confused:
 

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How do you mean erratic? The Alfa gauge is the ACTUAL temp in that it fluctuates. Many other cars show you the average. When the engine is cold, as it heats up it will rise, then suddenly drop as the thermostat opens, then slowly rise to around the 90 marker. However even then the guage may not be right. Mine is running at 84 when the gauge is on the mark mid-way between 50 and 90 and running at 94 when on the 90 mark! :confused: Fun ....
 

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How do you mean erratic? The Alfa gauge is the ACTUAL temp in that it fluctuates. Many other cars show you the average. When the engine is cold, as it heats up it will rise, then suddenly drop as the thermostat opens, then slowly rise to around the 90 marker. However even then the guage may not be right. Mine is running at 84 when the gauge is on the mark mid-way between 50 and 90 and running at 94 when on the 90 mark! :confused: Fun ....
Mine does the same. Shows just over 70 when the actual temp is 87 (readings taken on examiner) despite what the guage sys in my case fans are cutting in at right temp and ECU getting the correct readings. Apparently it's not unknown for the guages to be a bit 'sticky'
 
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One thing to note is that as you are driving, if you accelerate hard and then ease off, you will see the temp guage respond very quickly, like about 10s! Of course, this is literally the engine getting hotter and colder as the work rate goes up and down. Could it be this in your case?
 

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Discussion Starter #6
thanks for all your help so far guys but driving at constant speed,be it 30,50,70 or 90 mph the temp guage rises to about 92 degrees and then drops to 70ish degrees in about 10 seconds..then off it goes again up to 92 degrees.think i'm gonna change the sensor thingy that bolts into the thermostat as a process of elimination:rolleyes:
 

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Mines just started doing it after 14 months in my posession, was previously rock steady. Fitted new stat 6 months ago (old one stuck open). Would be interested to know if new sensor cures it.
 

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This might help, taken form Alfa156.net. I'm just about to replace my stat as it never gets off the mark.

Problem
The water temp rises too slowly, hitting 90c° only after 10Km (driving
about 90Km/h with 5c° outside), when temp reaches 90 it suddenly drops
to 75-80 and then rises a little but usually is always below 90c°.

Reason:
Alfa uses a different way of showing the temperature compared
to i.e. Opel, Audi, VW. I guess Seat is VW so......
The difference is that in fact the temperature always goes up and
down because there is a thermostat (in all cars!!) that opens when
the cooling circuit reaches a certain temperature like 90dgr.
When the thermostat opens, a whole lot of relativaly "cold" cooling
drops from 90 to 70-75dgr.
Alfa shows this immediately on the temperature indicator whereas many
other cars measure an AVERAGE temperature that goes up and down very
slowly and certainly will not show the peaks like the Alfa way.
I guess this is done because the "normal" car driver will get in panic
and goes and see their dealer to check if nothing is wrong and Alfa is
of the opinion that Alfisti, as real, true car drivers, as enthousiastic
and knowledgeable car dirvers and can "see through" this.
 

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I fitted the new stat at the weekend, now the temp rises to just over 90 and then drops to between 70-80 and then rises again and drops again, and so on... Which is how it should be in an Alfa. I suppose it takes between 30 seconds to a minute per cycle while driving at 50mph
 

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Discussion Starter #12
have fitted new sensor in stat,its called an "engine management sensor" cost £22 and is exactly the same as before and would so appear that alfa temp guages move from 70-90 dgr all the time
 

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Sure, they very rarely go wrong, as there is nothing much to go wrong with them, its other management sensors like the air mass meter that more commonly fail. Normally the orange engine managment light will show if there is a problem and you may get restricted power. I have had no end of problems with that bloody little light on previous cars, though touch wood my Alfa has behaved it's self. It's the best car I've owned, I don't think I could own anything else! Well maybe a 166 one day!
 
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