Radiator Fans Not Working

[ondra]

Can anybody point me to the right direction where is the temp sensor which switches the fan on. My a/c doesnt work as the pipe from the front rad broke off, but i dont think that would cause the main fan failure.. Connected both fans to 12v supply and they work, so its got to be the switch. Car is getting hot on the motorway and I`ve got only 10 days to my holiday. ;)

[gio]

sorry cannot help with the switch thing, but the car is getting hot on motorways?

 

Well that shouldn't be happening regardless of the fans working or not.

[insider]

I would tend to agree with gio - the fans are unlikely to have to operate at motorway speeds as there would be more than enough cool air flowing over the radiator. Have you checked the following?

 

Anything blocking the radiator grille?

Coolant level, any leaks?

Slipping drive belt?

Is there air in system?

Thermostat?

Expansion tank and/or cap and seal.

Radiator blocked?

Water pump (there are known problems with plastic impellors breaking - search this site)

[ondra]

I`ve fitted new pump yesterday it looked allright, but changed it anyway, pump is cambelt driven so no slipping ;) .took the thermostat out and flushed the system, no sign of blockage.New thermostat and coolant in the engine. Going for the test drive now..

Is there a way how to test the expansion cap??

Thanks for the reply, will update after test drive.

[Bigjeeze]

When my Air con pipe developed a leak the first thing I noticed was the fans NOT coming on - Once I had it re gassed (after fitting a new pipe) the fans re started. So I think it may be as the OP have said and not the fans or switches at all.

[clown]

When my Air con pipe developed a leak the first thing I noticed was the fans NOT coming on - Once I had it re gassed (after fitting a new pipe) the fans re started. So I think it may be as the OP have said and not the fans or switches at all.

 

 

 

Ondra,

 

if your engine exceeds 90

[Tony]

Hi

I had a similar problem and found the fan relays (1 unit incorporating 2 relays) by the battery were switching intermitantly once replaced all worked fine. I have a 2001 TDi.

[ondra]

Thanks for the tips, but i think there is a Bigger problem ;) . Please, can anybody tell me this is not a head gasket failure.... ;) See picture

[Smilge]

Ondra ...mmmmm ...... looks dodgy but this may be just caused by condensation on the filler cap. Have a good look around the rocker box with a torch and a close look at the dipstick. I would then remove the expansion tank cap (engine cold), start her up and see if any air bubbles appear. If your still not happy then go and get the system pressure checked. Do you get a lot of steam from the exhaust?

[ondra]

No steam at all and the oil in the sump looks fine (changed about 1000m ago) I am really confused.. Yesterday on the test drive it blew off the thermostat rubber seal, so it is overpressurized. the water from the expansion is disappearing while the engine is hot, when you open the cap it comes back. Going for a new thermostat now, and will try again.

[Smilge]

Sounds reasonable mate and the expansion tank will fill up again when you release the cap but it shouldn't disappear when the engine is warm. This sounds like you need to check all the hoses / joints meticulously and with the engine warm, squeeze the hoses. If there is any air in the system you'll find the hoses very difficult to squeeze. Just be careful you don't burn your hands.