2004 S40 T5 radiator fan (relay???) noise help requested

sootyboy · Post by **sootyboy** » 22 Oct 2008, 07:01

Hi, I have a 2004.5 S40 T5....perhaps I have not been able to hear it until the last 6 months or so, but I am noticing some fan stays for around 15 seconds or so after my car ignition is turned off, regardless of the weather. My Volvo technician says it is a radiator fan and due to the engine size, this noise (almost a whining) is normal; he has put the car through computer diagnostic tests and says nothing is wrong, but it just does not seem right to me. I certainly did not hear this noise when I was considering purchase of the car back in 2004...You folks have the experience and expertise, what is your opinion please? Thanks very much.

Post by **billofdurham** » 22 Oct 2008, 15:48

Welcome to Matthew's Volvo Site.

The radiator fan is designed to either stay on or come on after switch off if it detects the coolant temp is above normal. It can run for up to 6 minutes to remedy this. The temp gauge may not show that it is running hot but the sensor will detect it.

Bill.

volvonewbie18 · Post by **volvonewbie18** » 09 Mar 2009, 14:00

what if the fan has to come on while youre still driving...i noticed my temp gauge went up to the red while i was idling then it went down to normal as i started driving...i parked and noticed that my coolant was overflowing, not sure what that means cuz i just got my oil changed yesterday and they said my fluid levels were fine. heard it could be a number of things

Post by **MadeInJapan** » 09 Mar 2009, 15:21

Sounds like you need a new thermostat.
While in to change it, it's not hard to also change your ECT (engine coolant temperature) sensor. I would highly recommend you do both. Overheating your car (aluminum engine) could mean the death of your engine. Btw, the fan coming on is normal- it is trying its darnedest to cool your engine down.

volvonewbie18 · Post by **volvonewbie18** » 10 Mar 2009, 17:20

im a little confused, my car is overheating because it has a bad thermostat ?...i thought the thermostat just measured the temperature or does it initiate the cooling procedures (fan) too? also, i noticed that when the car temp starts to rise, i can turn the heater on and it works for a little bit...how long can i keep doing this b4 it causes a serious problem, i'm broke right now or i would've already replaced it.

Post by **MadeInJapan** » 10 Mar 2009, 18:16

The is the way it was explained to me and how I understand things. The thermostat opens the passageway at a certain temperature to let the hot coolant out of the engine into the radiator where it is cooled, pushing the lower temperature coolant back into the engine to cool it...that's about all it does. The ECT (engine coolant sensor) actually activates the fan by the temperature of the coolant that is pushed past the thermostat. When the thermostat is broken, the open/close function is disturbed leading to (usually) hotter coolant to stay in the engine... Even though the ECT turns on the fan, its functioning can become erratic, leading to even a greater increase in the engine coolant's temperature, thus the engine's temperature. That is why it's best to replace both the thermostat and the ECT at the same time.

volvonewbie18 · Post by **volvonewbie18** » 11 Mar 2009, 15:52

As always, u make things so easy to understand...thank you.

volvonewbie18 · Post by **volvonewbie18** » 12 Mar 2009, 09:36

so, the way i understand it is...if my thermostat is broken, then its not opening the passageway for the hot coolant soon enuf, therefore as it passes the ECT the coolant is already above the critical temp for the ECT to turn on the fan. So the fact that the fan comes on means that the passageway has been opened and the coolant should get cooled in the radiator and cooler coolant should be released into the engine. (is this a continuous process or is it a one time thing...does it depend on the constant reading of the temp by the thermostat to depict whether it has to open the passageway again...it would seem that the engine won't immediately cool off on one cycle of new coolant) if it was the thermostat then the cooler coolant directed towards the engine would cool it down but the thermostat may not recognize the reduction in temp. What tells the fan to turn off? the ECT? if so, then that must mean that the passageway stays open for the coolant to pass thru.

logically, im missing somthing...i was wondering if the radiator could be failing to cool the coolant, would it make sense to change all three out? either the the engine coolant is getting too hot b4 the thermostat opens the passageway, or the radiator is pumping out uncooled coolant back into the engine....could you please correct my thesis lol

John Cherubini Dublin · Post by **John Cherubini Dublin** » 12 Mar 2009, 10:55

Hi sootyboy,sounds like you've got more problems than the whining noise!! However i found on my previous 850 that a spray of WD40 into the fan motor ridded the whining noise for me.
Good luck

Post by **MadeInJapan** » 12 Mar 2009, 16:54

Thermostats can break open or closed...the flow of coolant is continuous. Now, try to figure out the logic. Also, continually over-heated coolant will stress the ECT...causing it to malfunction- follow that logic as well. As long as the radiator is not leaking- there is no need to change it out. It's just good practice to change both the ECT and thermostat at the same time. Other issues could include bad baring in the fan motor or bad fan relay.