my dads cosworth keeps overheating due to the radaitor fan not coming on at all.

the only thing i am gettin is that it only happens after an hour sat on tickover and it goes into the red, then i get the header tank and it bubbles over and dissapears thorugh the bottom off the car.

i have already tried the themostat and put a new one in...

any ideas or when does your fan kick in? help as this bits stopping me from driving it

 

Mine was doin this but after about 5-10 mins sat in traffic in the end i found it to be the rad . It wasnt gettin hot at the bottom so the fan swich didnt think it was hot . Tried a rad flush but didnt work so i bought a Pro-alloy rad and its now sweet

 

i'd short the connector on the back of the radiator and see if the fans come on.
Mine boiled over once, opened the fuse box, touched the fuse and they came on. never had a problem since. there is also evidence on the lid of the fuse box that the rad fan fuse has got hot at some point, don't know if this is common.

 

wire it up though a fuse m8 and have a switch in the car 17 year old wiring for you should kick in around 88degress

 

Common complaint on cossies this, I found mine ran a huge amount hotter with the sheild in place between the rad and intercooler, and once fans had come on they would stay on for ages trying to get rid of heat.
Took air deflector off, 95% better, it seems to help hold in the heat when fitted.
tabetha

 

Sorry for hi-jacking this, are the fans on a Saph supposed to stay on after the car is turned off?

My last one did this a lot, new one hasn't so far!

 

I beleive that they are wired permanently live so should stay on after turn off of ignition, never tried mine so not 100% sure but sure I have read they are wired permanent live.
tabetha

 

mine run after its switched off

andy, i believe i ave a wiring diagram to make up a new loom for the fans somewhere

 

Fuse and wiring, happens to all fucking Cossies don't it.

And mine stay on sometimes when I turn off the car.

 

temp gauge on mine goes all the way to the top of the N then they come on for ages. Try the fan switch mate

 

Fuse box connections go into meltdown mode my mate just moved the wires in the fuse box to a spare fuse and fans av been fine eversince.He said its a common problem on cossies as they get older.

 

it will be your rad no good block at the bottom u need to replace it with a new one .this happened 2 me no fans boiling up in the red relpaced rad all working fine now ... bridge the fan switch so it won t boil up and get it done asap matey

 

i've just ran in to an overheating problem too,

she boiled over at weekend after i'd been out for a run in her, bled the system and ran it up so no air pockets but had no fans come on,
so ordered a 82 degree thermo and rad fan switch and fitted them, ran it up again and still no fans!

have wired the fans up direct from the batttery and they work fine so I by-passed the rad fan switch with the aid of a split pin but still no fans!
the relay is clicking and have changed it for another ford one which does the same and have also checked the fuse and this is ok.

so has it got to be the wiring from the relay back to the fans or is there something else i could try??

many thanks
Dave

 

The fact that the relay is clicking suggests that the relay is working (ie switching) and the fan switch is OK, but that you've lost the 12V feed that should between the battery to the relay, or between the relay and the fans, or betwen the fans and earth. Time to get your multimeter out.

 

anyone know which prong on the relay is the one what goes to the + side of the rad fan

plan for tonight is:
plug negative plug up an run a wire from battery to positive side to see if earth works,

if it does run a wire from relay to fan see if power is relay,

if not run wire from battery to relay an see if that works

if none of that works gonna hard wire it so it constantly works with a 30 amp fuse in it until i can make a new loom up!