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Xflow cooling fan switch, radiator or top of head?

steve m - 21/2/13 at 02:10 PM

Having changed my Radiator to a polo one, on the xflow, i now have a cooling fan switch on the rad, as well as the water filler on top hose/head

which is the better one to use, rad or head switch, or could i even use both, but independently ?

regards

Steve

snapper - 21/2/13 at 02:19 PM

Don't see it as an issue, there only a foot apart and temp won't change much in that distance
If pushed I would go for head temp as its the engine temp not rad temp that is critical

Paul Turner - 21/2/13 at 02:24 PM

Had it in the head filler on the cross flow and now in the radiator with the Zetec. Works fine in either location.

Don't wire both in, you may end up confusing something.

phil m - 21/2/13 at 03:01 PM

Hi
Mines a cross flow with the fan switch in the polo rad

britishtrident - 21/2/13 at 03:39 PM

Job of the fan switch is to control the radiator outlet temperature not the engine temperature, provided the rad outlet temperature is not too high the engine temp is controlled by the thermostat.

Just screw a 22mm fan switch in to the Polo rad, choose a switch the switches in a few degrees higher than the thermostat fully open temperature and switches back off close to but still slightly above the thermostat temp.

The 22mm fan switches used by some Fiats including the early Pandas have standard spade connectors so you don't need a special plug.

steve m - 21/2/13 at 04:30 PM

Thanks all,

BT, im your experiance, which is better rad switch, or top of block ??
or does it really not make that much difference

Steve

britishtrident - 21/2/13 at 05:30 PM

Rad switches were more or less standard practice until manufacturers switched to using ECU control for the fan. Ford were the exception to this probably for production reasons.

renetom - 21/2/13 at 06:11 PM

Hi Steve
We have a polo rad with a fan switch in
& it works fine , when the temp gauge says 95
it switches on & off when the temp drops
Whatever your little heart desires.
good luck
René.

Paul Turner - 21/2/13 at 06:56 PM

quote:
Originally posted by britishtrident
Rad switches were more or less standard practice until manufacturers switched to using ECU control for the fan. Ford were the exception to this probably for production reasons.

On the Zetec Silvertop the fan switch was in the thermostat housing. In the Zetec Blacktop fitted to the Focus the fan was ECU controlled with sensor in the head.

joemotion - 27/2/13 at 08:55 PM

Sorry to hijack but Im after a rad thermo switch for a polo rad that comes on about 85 degrees. The one i have is coming on at near on 100 and is getting too hot. Can anybody link me to somewhere on the bay that supplies the right one?

Cheers

Joe

[Edited on 27/2/13 by joemotion]

Trollyjack - 27/2/13 at 09:07 PM

quote:
Originally posted by joemotion
Sorry to hijack but Im after a rad thermo switch for a polo rad that comes on about 85 degrees. The one i have is coming on at near on 100 and is getting too hot. Can anybody link me to somewhere on the bay that supplies the right one?

Cheers

Joe

[Edited on 27/2/13 by joemotion]

Does you rad switch have 2 or three conections some have 3 and they can switch at either 90°c or 100°c

joemotion - 27/2/13 at 09:23 PM

Cant remember offhand without checking but probably just the two wires going in. Either way can one be purchased that kicks in lower? I like her sitting no more than 85

Trollyjack - 27/2/13 at 09:35 PM

quote:
Originally posted by joemotion
Cant remember offhand without checking but probably just the two wires going in. Either way can one be purchased that kicks in lower? I like her sitting no more than 85

Try here Radiator Fan Temperature Switch Audi/Vw 06031 | eBay
Radiator Fan Temperature Switch Audi/Vw 06031

This one switches at 87°c

joemotion - 28/2/13 at 02:21 PM

Cheers

britishtrident - 28/2/13 at 07:07 PM

quote:
Originally posted by joemotion
Sorry to hijack but Im after a rad thermo switch for a polo rad that comes on about 85 degrees. The one i have is coming on at near on 100 and is getting too hot. Can anybody link me to somewhere on the bay that supplies the right one?

Cheers

Joe

[Edited on 27/2/13 by joemotion]

97c is a typical cutting temp for a rad fan 85c is very very low even if you have an 88c thermostat.

Coolant boils about 118c if the cooling system is water/steam tight.

Paul Turner - 28/2/13 at 08:51 PM

When I ran a x-flow it was always fitted with a 74 degree stat and ran at 78 degrees summer and winter. The radiator fan switch was 85 degrees and the set up worked perfectly. Never had a head gasket problem or other similar failure in 14 years. Pretty sure the 74 degree stat is no longer available, the last one I had was sold on e-bay for a stupid price as bidders went crazy for it, even got bids form the US.

The current Zetec has an 88 degree stat in it with a 95 degree fan switch, again the set up works perfectly summer and winter and has done for 11 years.

greed1 - 28/2/13 at 09:40 PM

Im running a 75 degree stat from a jaguar, temperature stays at 78 although not had chance to run it in the summer yet fan just on a switch on the dash soon to be an 85 degree switch in the top hose. No problems so far

David Jenkins - 28/2/13 at 10:08 PM

quote:
Originally posted by Paul Turner
Had it in the head filler on the cross flow and now in the radiator with the Zetec. Works fine in either location.

Don't wire both in, you may end up confusing something.

I have wired both switches in parallel - basically, I had to plug the hole in the radiator with something, so I used a thermostat! Wired them both in parallel, on the principle that if one fails, the other will still do the job. Works nicely, and no problems found after many years of use.

[Edited on 28/2/13 by David Jenkins]