fans - who needs 'em?

[tim]

Bit of an odd one.... the wife's BX has done nearly 300,000 miles and she's clocked up half of that. She reckons she's never heard the fan work but the car has still happily gone from A to B for years without cooking, frying, or boiling. Last week the rad sprang a terminal leak so I fitted a new one and found that the sensor at the bottom was so rot that one terminal wasn't even there and the other two were crusty green. I couldn't find a replacement locally - any ideas who DOES sell them??- fortunately the one off our scrapper was OK so I cleaned it up, cut back the wires until copper showed rather than green powder and added some terminals.
Three days ago we did the weekly shopping run and arrived in the supermarket car park. As we stopped we could hear a whirring noise.... the fan was working for the first time in ten years! So I'm just curious really....if the motor can run for so long in all conditions without the fan, how essential is it?? It's nice to know these things. This one only has the one fan, whereas mine has two; I presume this was part of a towing kit package. These both work as I saw them kick in after running on the ramps for ten minutes. This suggests that they do have a job to do, and yet the other one has suffered not at all from the lack of a fan. Though it has to be said that it's a 'country' car and maybe fighting a city rushhour every week would have had more terminal results....

[Gibbo2286]

Don't know why you managed without the fans but here's where to get the parts. Gibbo.

http://partfinder.smpeurope.com/index.h ... &fullid=-1

[toddao]

Luckily you live on the cold island!* I just think it hasn't got hot enough to require the fans otherwise you'd have been looking at the head gasket palaver and probably more. Obviously no big long hills around thereabouts?

(* yeah, I know it's warmish over there at the moment)

[djm666]

GSF do them

[Tim Leech]

I do, my TZi got rather warm today sat in traffic and got up to nearly 100 degrees on the temp gauge but the fan cut in and normal service was resumed. Its always been quite a warm engine, ive changed the coolant and thers no airlocks

Maybe I should fit a diesel temp sensor?[/list]

[Mothman]

Hi Tim,

never heard the fan on mine work either until i replaced the rad a couple of years ago. Cleaned all the terminals like you, including everything to do with the fan and got it working. Havnt heard it since either, even when doing long runs to Looe n back.
As long as no red lights come on ime happy.
See you Saturday.

Andy

[themildbunch]

Hi

I replaced mine with a lower temperature FAE one from Eurocarparts when I did my water pump recently. The part number is FAE 3780 but FAE have a useful online catalogue with all their parts an applications listed...... It cut in on low speed yesterday when I was idling for 20 mins..


adrian

[electrokid]

If it's a diesel it won't need the fan unless you're stuck in traffic for a while.

The temp switch is not in an ideal place - directly under any overflow from the rad after top-up - and it's at the bottom where road spray can get at it too so it's no surprise that the terminals rot away.

From there the wiring goes across the front of the car to a connector close to the NS headlamp - I think it's supposed to be protected to some extent by the plastic screen below the headlamp but if that's been disturbed then it's easy to leave the connector out in the wind and rain too - and that will rot and go open circuit as well so it's worth checking where it is and its condition.

Lower temperature switch - very good idea.

[kiwi]

I think my TRS is telling me something

THe Fan no longer works unless I bypass it directly to the battery, which is what I had to do today while working on where the Matrix was leaking. Saw an orange light in a place it should not be on so replaced the sensor with a spare I had and still nothing.

Any ideas folks on ways to test the sensor?

[electrokid]

There are a variety of temp sensors fitted to the BX. The one controlling the fan is at the bottom of the rad - check by removing it (save the coolant if it has antifreeze in). connect it to a meter or test lamp so you can see if the switch operates and dunk it in boiling water. From memory it should switch at around 75-85 °C.

[kiwi]

Solved the problem

Rule 1, check fuses

Rule 2, If in doubt check and replace the fuses.

Rule 3, If still in doubt check those fuses again.

Guess which rule after replacing and checking the therm switch applied

[electrokid]

excellent

The next question is 'did it jump or was it pushed ?'

Fuses suffer from mechanical wear ! Because the fuse rating is close to the running current it warms up when equipment is switched on and cools down again when it's switched off - so it expands and contracts - in the old clear glass fuses it was not uncommon to see the element move when the load changed.

Expansion and contraction can weaken the element and crack it.

It probably jumped

[Defender110]

As Brian has said fans will rarely kick in unless stuck in traffic for long periods or heavy towing. A high temp running engine will do know harm as long as it doesn't reach boiling point. It was common practice in Land Rover circles to remove the mechanical viscous fan all together and run without if not used for towing or serious off roading.
In our silent running film generators with restricted air flow blimps we use a 50% antifreeze coolant mix which raises the boiling point of the coolant and prevents air locks from boiling when they are running at their max, i used this trick with great success on my Jensen Interceptor to eliminate static boiling after switch off which they were proan to with there mighty 7.2 litre V8 engines. (I miss that car , but not the fuel bill)