A friend of mines s70 radiator fan stays on without turning off. plus when he said when he adds coolant, he always has to top it up every month. there is noo visible leak. what could be the problem. his oil kind of look okay to me without any milky look. could that be a thermostat problem? thanks guys

 

I just fixed my coolant switch for the exact opposite problem, the fan would never come on. It is possible that the switch is shorting out making the engine think that it's hotter than it really is. How's the temperature gauge reading?

 

l did not check the temperature guage yet, l will ask him how his temperature gauge works. l will ask him to change his temperature sensor and see if it helps

 

Unless the sensor is leaking this isn't going to fix it. The fan is already working so it's much more likely you have a small leak somewhere.

If you can't find any sign of leak then you might need to add some dye to the system and use a black light to see if you can find it.

It is possible you have the beginnings of a head gasket failure but saying he has to top it off each month seems to make it sound it's been going on for some time and usually they get worse as time goes by.

You can get a loaner tool from a parts store to try to test at the coolant expansion tank for hydrocarbons just to make sure it is/isn't the headgasket.

 

Yes and yes.

When our S70 head gasket went south it was loosing a little coolant and some had to be added monthly and just got worse.

http://atthetipwebs.com/technologyin...ead_gasket.htm

Then, when the rad fan wouldn't turn off after the drive, it was the ECT sensor that went bad.

 

 

 

he said he doesnt smell anything funny but see white smoke when he turns on the heater. which sounded strange to me.l will call him and ask him to come over and l can check that out. thanks

 

yea his coolant bottoms up after adding coolant. needs to add more often. will check it out when l get the chance. thanks

 

Only add coolant when the car is cooled off. If it expands in the reservoir while driving it's likely a head gasket issue.

So, when my daughter started the car the low coolant light was on. Then it would fill up as the car got hot.