Hi all! I hope someone checks out this part of the BB, as I understand the 460 was not sold in the USA. My 460SE automatic overheats (gauge rises from 3/4 to almost the red mark) unless the AC is on. Even if I drive at highway speeds, the temp will rise until I turn on the AC; it then returns back to the 1/2 mark and stays there. What's weird, is that this car doesn't have a separate booster radiator fan for the AC... The car isn't loosing any coolant, radiator looks clean, and the fan is making its cycle properly. I am tyred of freezing myself in the cabin to keep the engine cool, so your help is greatly appreciated!

Thanks;
JGCBAIZ.

Because the lovable 460 is not allowed in the USA, we are stabbing in the dark.\

If the engine cools off when the AC is on, I would suspect that the radiator fan is not working as it should. When hot, the fan should be on "high" all of the time. The AC setting will turn the engine fan on to cool the condenser and cause the radiator to cool off. It might just be a fan relay that has gone bad.

I never knew that it got cold in Columbia :)

Klaus
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The 164 has a new home, all I am left with are a 95 854T and a 98 V70R :)

I would look at the drive-belt and a/c clutch. Any source of friction there might lead to cumulating overheating. How is the electrical (voltage regulation) with the a/c on or off? Maybe the clutch electromagnet is drawing overcurrent or partly shorted? Overloading the electrical system?

Beyond that, it's hard to relate specifically with the a/c.

Also is the coolant thermostat sticking sometimes?

You could also feel around when the engine is starting to get too warm if block, radiator, hoses, etc. are all at similar temperature - if not, then the coolant may be circulating poorly.

Finally, what happens if you switch on the car's heater? I don't know about the 460 series - the 850 series has coolant running through the heater always, and the heat is just redirected to or away from the car's cabin as selected. On various other cars, maybe the 460, coolant runs or does not run thru heater according to the passenger heat setting.

Hi all and thanks for replying! The fan relay should be fine, as the fan does kick in (and cycles properly) with the AC on or off. I drove today with the AC off and noticed the gauge rising to about 3/4, but it stays there. Using the heater has no effect. I went to the dealer today to pick up my 940 and they tell me that it is normal for the 460 to operate at high temp, but I am not the least convinced... They tell me there is a sensor for the gauge and another for the fan control, so one of these must be giving inaccurate readings, as the fan is shutting off when it reaches a certain temp, but the gauge is still showing signs of overheat... I will check the thermostat and heating rate for the various engine parts...

Thanks and looking forward to more ideas;
JGCBAIZ