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Discussion Starter #1
Hello every one,

I am living in a place where the climate is hot near 30 degrees i have 2.5 v6 cf3, and it runs hot, i did some diagnostic and found the low speed fan start at 97c, is that something normal ? when should the first low speed start and the high speed start ? as far as my knowledge with bmw and other cars the low speed fan should start at 90c 91 or something and the high speed starts when it is over 100
 

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The low speed should start at approx. 92 °C and the high speed should start at approx. 98°C.
If the car has AC, the low speed will also start when the condenser needs cooling.
In the low speed a resistor is put in series with the fan to slow down the speed

To me it sounds like the low speed don't work in your car.
I assume your car has two fans right?
It has seperate circuit for the too fans (relays and resistors). Maybe both of your resistors have failed.
Have you used MES (MultiECUscan) to check if both fan speeds work?
 

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Discussion Starter #4
The low speed should start at approx. 92 °C and the high speed should start at approx. 98°C.
If the car has AC, the low speed will also start when the condenser needs cooling.
In the low speed a resistor is put in series with the fan to slow down the speed

To me it sounds like the low speed don't work in your car.
I assume your car has two fans right?
It has seperate circuit for the too fans (relays and resistors). Maybe both of your resistors have failed.
Have you used MES (MultiECUscan) to check if both fan speeds work?

Yaaah I did, both first speed and high speed works with the MES, i changed the engine temp sensor and it solved the issue for me, but when i drive the car aggressively the temp raises to 97 or even 100 and i have to slow down so the temp goes back to 92,


another thing, what i understood about the fans circuit that it is for high speed and low speed not for the first fan and the second fan,
 

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Ok, in that case then it could be the water pump that is worn and has a poor performance or if the radiator fins are corroded, restrict the airflow and don't cool enough
 

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"when i drive the car aggressively the temp raises to 97 or even 100 and i have to slow down so the temp goes back to 92" this sound to me like water pump.
 

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Ok, in that case then it could be the water pump that is worn and has a poor performance or if the radiator fins are corroded, restrict the airflow and don't cool enough
Before getting the pump changed, carefully check your radiator and the A/C condenser in front of it. If the fins are either damaged or corroded it will reduce airflow. Be especially careful if your car has the old copper radiator (painted black fins) as they turn to dust.

The 2.5 came with a plastic impellor which is prone to cracking and then slipping at high engine speeds but this has been known about for many years so it would be better to ensure it is not simply the radiator.
 

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My jts has the same properties. I connected ecu scan and watched as slow speed fan didnt come on until about 96oC. I thought it was the dial but the temp at which the fan came on corresponded with what the dial wad reading. It cools the car back down to 88-89 fairly quickly in my case but i dont know why its doing that. Ive been told thd fan on/temp particulars are set at the factory
Cheers
 

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Discussion Starter #10
Guys i changed the water pump, and the same issue the first fan speed starts at 97.... is this normal ? i changed the engine water temp sensor and the same, could this be sensor for cold places ?
 

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The 97°C you mention is it the temperature reported by the Engine ECU?
Or it it a read out from the gauge?

Do the car still get warmer when you drive it hard?
 

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Discussion Starter #13
The 97°C you mention is it the temperature reported by the Engine ECU?
Or it it a read out from the gauge?

Do the car still get warmer when you drive it hard?

Yes same issue with new pump, when it reaches 97 the slow speed kicks in, and this is not a gauge issue as i read that through MES, the first speed Kicks in at 97, could this be engine temp sensor issue ? that it sends the data to the ECU at 97 ? could be that ? And is this the normat behaviour for the CF3 2.5 v6 ? or is there is another engine temp sensor that it reads for example at 92 ? i need answers :'(
http://tinypic.com/r/8yx6yb/9


 

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I have checked the workshop manual and it is not mentioned anywhere at which temperature level the low speed and high speed should kick in.

As the 97°C kick in for low speed you mention is reported by the Engine ECU it can't be a temperature sensor problem.
The temperature sender is just a NTC resistor (NTC stands for Negative Temperature Coefficient)
The resistor decreases with higher temperature and the Engine ECU just measure the resistance and use a look-up table to convert the resistance to a temperature.
A certain resistance corresponds to a certain temperature

So it seems the software in your Engine ECU is set to enable the low speed fan when the Engine ECU measure 97°C cooling water temperature.

As the temperature sender includes a second NTC resistor for the gauge there can be a mismatch between the temperature reported by the Engine ECU and the temperature shown on the gauge.

I can try on my own 2.5 V6 to see at which temperature level the low speed kicks in.
 

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for most (all?) the later models, the temp. settings are:
low speed: 95 degr
high speed: 102 degr

as measured by the ecu.
 

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Discussion Starter #17
I have checked the workshop manual and it is not mentioned anywhere at which temperature level the low speed and high speed should kick in.

As the 97°C kick in for low speed you mention is reported by the Engine ECU it can't be a temperature sensor problem.
The temperature sender is just a NTC resistor (NTC stands for Negative Temperature Coefficient)
The resistor decreases with higher temperature and the Engine ECU just measure the resistance and use a look-up table to convert the resistance to a temperature.
A certain resistance corresponds to a certain temperature

So it seems the software in your Engine ECU is set to enable the low speed fan when the Engine ECU measure 97°C cooling water temperature.

As the temperature sender includes a second NTC resistor for the gauge there can be a mismatch between the temperature reported by the Engine ECU and the temperature shown on the gauge.

I can try on my own 2.5 V6 to see at which temperature level the low speed kicks in.
My Car is a CF3 version, has only 1 temp sensors that is sending to the ECU and the Gauge,also i changed it 3 times and same issue even the gauge i just changed it, the previous owner sold it for this issue, and i thought its something i can fix :D but i think this will kill me before i fix it
 

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Discussion Starter #18 (Edited)
for most (all?) the later models, the temp. settings are:
low speed: 95 degr
high speed: 102 degr

as measured by the ecu.

and how can i change that on the ECU maps ? did any one try to do that ? i have tried that in my previous e46 330 following the instructions on this website
 

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for most (all?) the later models, the temp. settings are:
low speed: 95 degr
high speed: 102 degr

as measured by the ecu.

and how can i change that on the ECU maps ? did any one try to do that ? i have tried that in my previous e46 330 following the instructions on this website
Perhaps you cant.
Theres been loads of input on this thread, from various models including 147 156 etc
Somebody said that the 147 dial is designed to operate so that it shows 90oC steady when the actual temp fluctuates between 85 and 95

If the operating temp is 90 then it makes no sense to turn the fan on at 91 or 92. It would wait till 95, then come on to cool the car down.

Maybe the manufacturer doesnt want us to see this fluctuation as its disconcerting to the driver but on some models the needle DOES indicate the change because...well....its an alfa and consistency is boring and not part of Italian flair and style. (No two alfas seem to be the same).

If the car does not steam or lose coolant and the fans seem to work and, in general ,there's no drama, then maybe its fine to leave it alone ?
 

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Perhaps you cant.
Theres been loads of input on this thread, from various models including 147 156 etc
Somebody said that the 147 dial is designed to operate so that it shows 90oC steady when the actual temp fluctuates between 85 and 95

....
Yes, but that's only for later models with a CAN bus, like 147. The temp as measured by the ECU is processed and sent via CAN to the guage, see
 

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