cooling fan trouble

i got my 164 about a month ago and am loving it, only thing is the fan on the rad runs as soon as i turn the ignition on, ive had a look under the bonnet and the factory wires appear to have been cut and a bypass put in with some other wires??. if anyone can explain this and why someone mite do it and a possible fix, both me and my car would be grateful

I would guess the temp sensor has failed. To prevent overheating someone has shorted it out. Sometimes people put a switch in line so they can switch the fan on and off themselves (why they don't just replace the sensor is beyond me). Find the sensor, check for open circuit when engine hot. If yes, sensor knackered. New sensor to fit. If the bodged wiring is easy enough to put back to normal, do so, if not, cut into the circuit and run it through the new sensor (it's just a thermostat switch)

Its a bit more complex. The Super has a two speed fan. It should run permanently if the aircon is on on low speed, but if not I 'think' its should cut in full speed at 87C (I'm getting a bit rusty in the memory dept). What often fails is the resistor in the fan cowling that control the speed, so people just chop it and build in a manual switch.

If you go to the 164 Site (Alfa Digest) they will tell you chapter and verse if you do a search, or ask Alfisto Steve, who knows EVERYTHING , as I said, I'm rusty on it.

AlfaLincs

Originally Posted by Mitch166

Sometimes people put a switch in line so they can switch the fan on and off themselves (why they don't just replace the sensor is beyond me).

Because they can fail again.
Replaced 1 to have the replacement fail within a few weeks, for no obvious reason - the replacement for that had no problems.

Plus some of us need to drive the car whilst waiting for the switch to come in.

Originally Posted by Cheradnine

Because they can fail again.
Replaced 1 to have the replacement fail within a few weeks, for no obvious reason - the replacement for that had no problems.

Plus some of us need to drive the car whilst waiting for the switch to come in.

Faulty part, get a free replacement.

yes but only as a temp measure, not permanent set up!!

sweet thanks guys ill get out n have a good look when the rain stops,

Originally Posted by 164gta

i got my 164 about a month ago and am loving it, only thing is the fan on the rad runs as soon as i turn the ignition on, ive had a look under the bonnet and the factory wires appear to have been cut and a bypass put in with some other wires??. if anyone can explain this and why someone mite do it and a possible fix, both me and my car would be grateful

Yes, this is a common repair which I dislike very much. The slow speed fan resistor has been by passed by connecting the brown and blue wires together and the high speed wired up to run with key on.

My suggestion is to replace the resistor, and repair all wires to run on 2 speed fan.

Here is a discussion about it with wiring diagrams and general info on the fan:
No low speed cooling fan operation - Alfa Romeo Bulletin Board & Forums

I run all my 164 and customers cars exactly how it came from the factory, have 0 problems with it this way. I see very hot temps here and never overheat, takes less out of the fan this way as well. Running all the time on high wears the fan FAST.

Jason

I Had A Look And It Seems Someone Seems To Have Done A Bodge On The Wiring To The Fan Red & Brown Wires It Seems As Though They Cut Them Were They Come From A Box That Has 3 Fuses And 2 Relays And Joined Them In And Earthed It All To The Engine, Although Its Working The Temp Only Gets Up To 70 On A Good Day, Must Admit Im A Bit Worried To Touch Anything As The Last Thing I Want To Do Is Cook My Engine.

Originally Posted by 164gta

I Had A Look And It Seems Someone Seems To Have Done A Bodge On The Wiring To The Fan Red & Brown Wires It Seems As Though They Cut Them Were They Come From A Box That Has 3 Fuses And 2 Relays And Joined Them In And Earthed It All To The Engine, Although Its Working The Temp Only Gets Up To 70 On A Good Day, Must Admit Im A Bit Worried To Touch Anything As The Last Thing I Want To Do Is Cook My Engine.

Yes, they just wired it to run with engine on. The other thing is that the car runs too cold in colder temps and MPG is decreased as well, plus it strains the alternator and electrical system running all the time.
If it where meant to run all the time it would run off a belt.

I would repair it to stock set up, follow the wiring diagram I have shown and you will be fine.
Clean it up, solder cleanly if needed and get it back to normal.

This method is a cheap way to cover mechanic's inability to figure out the electrical issue that is causing it to over heat.

The resistor is 98% the problem. Usually the thermal fuse is bad not the resistor itself. Easy repair.

Fix it soon or you will need a new fan motor on top of that as well as an alternator.

Jason

i had a good look today and i cant work out whats been done, the positive feed on the fan is joined into the purple and black wire that comes from the relay near the fan with the 15 amp fuse. ive tested for 12v in the cut oe wiring but theres no juice, can anybody help as i am having a hard time reading wiring diagrams. are the original wires that go to the fan 1red and 1 brown?? thanks