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Discussion Starter · #1 ·
So my 156 1.8 TS CF3 is running at around 85°c under normal conditions (main roads) - around 90°c on motorway, and it heats up as quick as I expect it.
However, sitting in traffic, even at days with only 18-20°c ambient temp, it will quickly heat up to +95°c.
The radiator itself is new (replaced by previous owner). Considering that heat-up and running temp is ok, I have a hard time believing that it's the thermostat causing this (unless of course it doesn't open fully).
The fan runs - although, I haven't checked if it actually goes on both speeds.

Where do I start? Say my fan does run on both speeds, then what?
I wouldn't dare a road trip to Italy, risking a traffic jam in 40°c...
 

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To me it sounds like your fan only run at high speed.
If the temperature rises and the fan kicks in, do the temperature continue to rise?

If the fan only run on high speed it is probably the resistor unit or the low speed relay that has broken
Do you have the wiring diagram?
 

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Discussion Starter · #3 ·
To me it sounds like your fan only run at high speed.
If the temperature rises and the fan kicks in, do the temperature continue to rise?

If the fan only run on high speed it is probably the resistor unit or the low speed relay that has broken
Do you have the wiring diagram?
The temp doesn't go down with the fan running.. So I'm more inclined to think it goes opposite of what you're saying - that it maybe only runs on low speed.
I will check fan speeds later today.

Forgot to mention that there's no coolant useage and level is fine as well.

I have access to AutoData, so I can pull out a diagram yes :)
 

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The temp doesn't go down with the fan running.. So I'm more inclined to think it goes opposite of what you're saying - that it maybe only runs on low speed.
I will check fan speeds later today.
......
I would also, if possible, compare the temperature as read via OBD with that displayed on the gauge (the OBD temp is the temp as read by the ECU).... The gauges on 156 have been known to be off.
Fans etc are controlled by the ECU, which uses a separate temp sensor. Gauge has it's own sensor.
 

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Discussion Starter · #5 ·
I would also, if possible, compare the temperature as read via OBD with that displayed on the gauge (the OBD temp is the temp as read by the ECU).... The gauges on 156 have been known to be off.
Fans etc are controlled by the ECU, which uses a separate temp sensor. Gauge has it's own sensor.
I'm aware the gauge is off - the temps I provided in the posts are actual temps, not read from the gauge, but through OBD ;)
 

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Discussion Starter · #8 ·
Switching temps for the fans are :

first speed: 95 degr
second speed: 102 degr

So as said, doesn't seem too abnormal.....
That high, really? My fan is mostly on, when I pull into my drive-way on the way home from work.. As I mentioned it's usually around 85°c under normal conditions, so why is it on that "low"? Because of AC?

Well I've seen it up to 98°c, before I've chosen to put the interior heating on full blast to keep it down..

I was unable to activate the fan relays via AlfaOBD, but I will try switching the relays around, just to verify that both relays are OK.
 

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If you turn on the AC, the fan will be on low speed if the condenser needs to be cooled.
If you can't activate the fan relays with AlfaOBD then try a free version of MultiECUscan to see if it will activate the fan relays

NB. you can PM me via AlfaOwner or via AlfaClub Denmark if you need live help.
 

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If the thermostat is not the original all these are normal i think. Some thermostats are more sensitive than others. But 98 is too much for TS i think. My TS 1.8 Euro3 in Greece hasn't ever reached this temp. Did you check if there is trapped air in the radiator's network?
 

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Well I've seen it up to 98°c, before I've chosen to put the interior heating on full blast to keep it down..
Seriously, that isn't over heating. Certainly no need at all to panic and put the heating on...

Remember that 100degC is NOT boiling for two reasons.
1) The coolant isn't water. So has a boiling point well over 100.
2) It is under pressure, which raises the boiling point even further.

I once used a coolant with a boiling point of 180degC.


But obviously make sure that the fans work at both low speed and high speed.
 

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Discussion Starter · #13 ·
Seriously, that isn't over heating. Certainly no need at all to panic and put the heating on...

Remember that 100degC is NOT boiling for two reasons.
1) The coolant isn't water. So has a boiling point well over 100.
2) It is under pressure, which raises the boiling point even further.

I once used a coolant with a boiling point of 180degC.


But obviously make sure that the fans work at both low speed and high speed.
But just because it's not boiling doesn't mean it's ideal.. To me at least, 105°c is pretty critical, but maybe I remember wrong.. But that's around where I'd expect the head to start warping :idea:
 

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Discussion Starter · #15 ·
I haven't.. And unfortunately I'll be busy most weekend, so won't be able to check until sometime next week.
 

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As already said, that's quite normal temperature readings as long as the fan kicks in at both speeds. If it was a K series rover, then I'd be concerned above 130c but not on a twinny.
Try bleeding the radiator. Get it up to full temperature remove the expansion cap and once the fan kicks in and open the plastic screw on the top left of the radiator O/S allow it to flow freely then close and top up coolant. Job done. Chances are you'll have a little trapped air which can raise the temp in a pressurised system.
 

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But just because it's not boiling doesn't mean it's ideal.. To me at least, 105°c is pretty critical, but maybe I remember wrong.. But that's around where I'd expect the head to start warping :idea:
I'd be surprised if merely reaching an indicated 105°C (or even more) caused a head to warp on its’ own, if there is no indication of coolant boiling. However it should be kept in mind that just because the coolant temperature at the point where the sensor is located may be X°, doesn't mean there isn’t a significantly higher temperature somewhere else (there almost certainly will be).

Even when the system is operating perfectly, the coolant temperature around the combustion chambers and exhaust ports will be significantly hotter than the coolant temperature at the point where the sensor is located (usually near to the point where coolant is exiting the head). As it moves through the head and nears the outlet, the hottest coolant gets mixed with coolant that is cooler, so the indicated temperature is more or less an 'average' coolant temperature, and not really all that indicative of the highest temperature it may reach inside the engine.

Having said that, if there are no obvious other signs of the coolant boiling (Can you hear it? Can you see evidence of expelled coolant? Is coolant disappearing? Are the hoses ‘hyper-pressurised’?) then I wouldn't be too worried. As David C said:
"Remember that 100degC is NOT boiling for two reasons.
1) The coolant isn't water. So has a boiling point well over 100.
2) It is under pressure, which raises the boiling point even further."

A 50/50 water / coolant mix raises the boiling point to around 106°C (may differ with different coolants?). Raising the pressure has more affect, with a 15psi increase raising the boiling point (of 50/50 coolant) to about 125°C. The 147 cooling system cap is rated at 20psi (1.4 bar), which is relatively high and will raise the boiling point a bit higher than 125°C (not sure how much higher).

It's my understanding (which I don't claim to be definitive) that heard warping is less to do with how hot the coolant becomes (below its’ boiling point, whatever that may be), and more to do with whether or not it actually boils and so creating gaseous steam in the water jacket, or, gasses otherwise becoming substantially present in the water jacket due to say a failed head gasket.

If gas is present in great enough quantity (regardless of the source of the gas) then it forms significant pockets in the highest and hottest parts of the water jacket (i.e. around the combustion chambers and exhaust ports). This allows these now effectively uncooled parts of the head casting to quickly become substantially hotter (than those parts of the casting that are still consistently in contact with coolant). But, the pockets of gas are not static, they can and do move with turbulence and the general direction of pumped coolant flow. When a gas pocket moves, the space it was occupying suddenly gets filled (more or less) with coolant that is likely to be a lot cooler than the uncooled metal in that part of the casting. The result is a thermal shock (or repeated shocks), and possible warping as a consequence.

If a significant amount of coolant boils then the internal system pressure increases exponentially. From memory, a liquid turning to gas expands something like 600 times in ‘free’ volume, though the trapped pressure itself tends to inhibit the expansion ratio somewhat (because gas is compressible). Nevertheless, internal pressures skyrocket, and the relief valve in the system cap can’t flow enough of this gas to keep pressure under control, despite expelling gas and coolant. The whole thing becomes a self reinforcing feedback loop, i.e. the hotter the coolant becomes the more it boils and the more gas is created, the more it overheats, the more gas and the more the uncooled parts of the head overheat more and then suddenly get cooled, the more likely the head is to warp (or even to crack...).

As I said, this only my understanding, I stand to be corrected....

Regards,
John.
 
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