thermostat and fan?

At what temp should the fan cut in at? iv recently finished wiring a 16v conversion but the fan doesn't seem to want to cut in at any point and i am not sure if the thermostat is opening either during bleeding. I have followed the bleeding instructions and all im getting is the water constantly boiling over and the fan not cutting in. any help is appreciated :dontknow:

Just a a couple of thoughts…
Is the cooling system all connected up correctly??
If that's correct then you'll need to check the switch in the rad is wired up and everything connected as it should be. Have you got power the the fan? or the earth for that matter…
You didn't say if you have the original fan running or an aftermarket item..?

running a brand new 16v fan/radiator, all connected up correctly as far as i know, took the two wires off the thermostat and touched them together to see if the fan came on and it did so i am a bit stumped any other ideas?

a couple of quick checks
to check the thermostat below water pump - check if the bottom pipe of the radiator gets hot , if it doesnt you have no Flow through your radiator - hence the thermoswitch will also have no flow & only see cold water - of course maybe through thermal transfer the radiator would eventually! get hot

If the pipe does get very hot - i would say the thermoswitch is probably faulty

the bottom pipe should start feeling hot at approx 5-10 mins of the car running from cold.

hope this helps
baz

just checked the bottom pipe and it gets warm then hot but feels as though there's no pressure in it, is that normal?

Is there a flow of water at the header tank?

yep there's a flow into the header tank

Hello

The first time you fill the water system - run the car with header tank cap off - when the thermostat opens there will be sudden rush of air bubbles from the radiator coming up to the header tank(its not boiling) - when this happens sw of engine let car cool then do the procedure again a couple of times - then on the fourth time run the car with the cap on the header tank ( pressurized system will have a higher boiling point )
keep an eye on water temp gauge though
this is what i do when changing the coolant

this is basically what i have done mate but there was no sudden rush of bubbles, the water just steamed then began to boil over after about 15 mins.

no worries
I can only speak for a 8v dx engine - may be its a prob related to the 16v

I take it the water is boiling inside the header tank with the system sealed
does it overheat on run or just when its idling
the thermostat seems  ok from your discrip

yeah the water is boiling inside the header tank when it is sealed, well the temp gauge goes 3/4 of the way when it sits idling for long enough, then when its out on the road it goes nearly all the way to the end, cheers for the help by the way

well
The temp sender sits on the primary cct ( so to speak ) so this would probably tell me the secondary cct ( radiator cct is not opening or blocked ) so when your driving there is not enough water flowing through the radiator to cool the engine & the primary cct just gets hotter & hotter
i would def replace the thermoswitch and thermostat for all the cost from gsf & flush the radiator

ps gsf do a lower cut-in thermoswitch that i have fitted to my mk1 ( my fan cuts in just over the half way mark on the gauge )

sounds like a plan mate :wink: gsf are just at the bottom of my street aswell so not to far out of the way

run it from cold with the cap off, then go round squeezing all the hoses you can lay your hands on. every now & again blip the throttle to really get the coolant flowing. Keep the level topped up, and watch that every time you rev the engine a stream of coolant and bubbles comes out of the thin hose to the top of the header tank.

As its warming up feel the bottom rad hose, it should stay stone cold till the gauge gets to about half way, then it should get hot pretty quickly.  Keep going till the hoses get too hot to touch, or you see the level of coolant start to rise up/bopil in the tank. switch off and refit the cap.

The fan should kick in at 3/4 on the gauge, if it doesnt and the fan comes on when you bridge the fan temp sensor plug pins, you either have a blocked radiator, poor coolanrt flow or a broken sensor.

To help diagnose the above, feel the side of the radiator where the sensor is, it should be just as hot as the opposite end. If not you have a blockage.

Also the system will boil over if it cannot pressurise, which buggers up the cooling system as you end up with air around the sensors. a common reason for this is the header tank cap, since they're so cheap its worth buying a new one regardless.

its sorted now rubjonny but thanks anyway, all worked perfectly after changing the thermoswitch and thermostat, have other problems now also in this section lol