Cant get my fans to come on when car gets up to temperature, ive bridged the connection at the fan switch and they came on so i know there is power there, ive also swapped for an msd fan switch with new wiring. also there doesnt seem to be any pressure in the header tank at hot temps, i should at least hear a hiss when i take the cap off when its hot, i dont know where to look next.

 

Could be the temp sensor?

 

is that the one on the back of the inlet manifold? i bridged that today aswell and still nothing.

 

temp sensor is on front near thermo housing. cant see it being tht, is it goin into the red or atleast up near it, have you run it on the road, or just ticking over, checked for air locks, ?????

 

yeah it will go up into red, its mainly been ticking over but i have run it round the compound where it is not for long though. had it running without the top hose on the thermostat housing to get rid of all the air.

 

have you check all the hoses for heat, I guess its an rs turbo engine mate

 

The one that screws in the thermostat

 

lol calm down , good call

 

yeah, well its a zvh. all hoses seem to be hot. regarding the temp sensor, i replaced it for a new one when i built the engine.

 

If you bridged the switch and the fan comes on , must be the fan switch itself, what else can it be?

 

ive had 2 brand new switches to try and they still wont come on

 

Could your gauge be wrong?

 

switch not copatible with loom/fan. possible break in loom

just re read. are you using the std gauge? bear in mind they are waaay out 90% of the time. what temp should the fan kick in and what thermostat you got in?

 

If the fan works when he bridges the switch connector, then there is nothing wrong with the fan or it's wiring.

From what I remember with my RSTs (in the 90s so a long time ago) the fan only used to come in about 3/4 up the gauge.

There used to be quiet a few different colour temp senders for CVHs, and if the wrong one was fitted the gauge would be inaccurate.

 

Yeah they do come on around 3/4s and i was going to say there are different colours of senders so i would definatly check this as my first thought was the sensor!

If you cant find the fault soon and need fans put in a manual over ride switch for now

 

Have you changed the thermostat? For what it cost and how easy it is it may be worth a try

 

As said clearly the problem lies with the switch or the coolant not reaching the switch etc, I assume you actually have coolant?

Also are you sure it's getting hot enough for the fans to engage?

Martin

 

How will i know which colour sender to use? Yes i have a new 82° stat. My water gauge used to go to red so i thought it might be faulty so ive wired an aftermarket water gauge in and it goes to nearly 100° without any fans coming on, i dont want to risk boiling the coolant. There is water at the switch aswell because it wazzed out wen i swapped it for another one.

 

Contacts clean on the plug? Is it connected to the switch correctly?

Yes the fans should operate well before that temperature, especially in the case of "uprated" switch which brings the fans on earlier than the original.

Martin

 

Yeah its an msd one with two wires coming off it which have been connected with new connectors, its a proper headscratcher this one, lost my rag with it yesterday.

 

It's very simple, either the switch does not work or the coolant is not reaching the temperature required to close the switch!

When at the switch activated temperature, check for continuity across the switch terminals, thus showing whether the switch is closed or not!

Martin

 

standard fan switch activates at 102/103 degrees but not sure on the msd ones

 

have you got an rs turbo temp senser in it mate. think they are brown in colour, wen i change from xr3i to rs i had to change the temp sensor to xr3i one in rs block

 

Xr2i's have a brown one that i use in my xr3i and that works fine.

I imagine turbos will be different as they probably run abit hotter

 

As I say MSD "Uprated" switch brings the fans on earlier, around 90 degrees seems to ring a bell.

I doubt there is a particular switch one for a RST, the cars were never designed properly in the first place (although it's probably not an issue on a standard example) in any case they were built from the parts bin.

It's just the same story with the Cosworth, the standard switch is useless (This is the complete opposite to RST, fans come on to early then stay on for an eternity) it's the same item as found in a MK2 Fiesta!

Martin

 

As standard i wouldnt think you'd have many problems but how many are still standerd?

 

Exactly that, but then again build quality was never a strong point!

Martin

 

Cheers for all your help guys im not sure what colour the temp sensor is ill check when i get down my unit this weekend, thinking of taking it to norris motorsport for a setup i wonder if theyll look into it for me as its the only thing stopping it from going on the road