revjames · Aug 31, 2007

I was away camping at the weekend and there was this bloke with a disco like mine. He reckons that you can take the viscous fan off and wire in the 2 AC fans on the front of the rad to cool the engine and thus get more MPGs. Anyone else heard about this? Good idea or bad idea?

I am a bit reluctant at the moment because I still have issues with coolant loss at the moment. I fixed it for a while with radweld but now there is no pressure in the expansion tank when you take the lid off.

The Mad Hat Man · Aug 31, 2007

the principle is.....
a viscous/engine mounted fan is taking up a small amount of engine power all the time which the engine has to produce by burning fuel. An electric fan only uses stored power (battery) when it needs to come on - very rarely on most landies - therby saving you power (fuel) most of the time.

Mantamad · Aug 31, 2007

On some cars (not certain with the disco) the radiator fan that comes on for the air con runs at a low speed, then can speed up as required, if its wired to come on to cool the coolant, it may burn it out as it would likely be at the high speed all the time.

Your best bet would be to get an electric fan kit from Kenlowe or similar.

The Mad Hat Man · Aug 31, 2007

Mantamad said:
On some cars (not certain with the disco) the radiator fan that comes on for the air con runs at a low speed, then can speed up as required, if its wired to come on to cool the coolant, it may burn it out as it would likely be at the high speed all the time.

Your best bet would be to get an electric fan kit from Kenlowe or similar.

bollix!

Mantamad · Aug 31, 2007

The Mad Hat Man said:
bollix!

Hmmm, you think so.

As I said, I am not certain about the disco but I was actually quoting on how the system on a VW Golf works and often fails (unless you think that bollix as well), wouldn't want the guy damaging his engine if it all goes wrong.

The Mad Hat Man · Aug 31, 2007

Mantamad said:
On some cars (not certain with the disco) the radiator fan that comes on for the air con runs at a low speed, then can speed up as required, if its wired to come on to cool the coolant, it may burn it out as it would likely be at the high speed all the time.

Your best bet would be to get an electric fan kit from Kenlowe or similar.

alright - let me explain.
the bit above in red is bollix - cause....

a) I think the disco has a (viscous) fan mounted on the engine which will be "on" all the time the engine is running.
b) removing that will remove the inherent bhp loss and help with fuel consumption.
c) most landies are overcooled and any engine cooling fan will only be needed rarely.
d) because of that, the need for any electrical cooling fans would only be minimal.
e) they would, therefore, not be on at high speed all of the time.

the only q are
how you would control the air con fans to operate by two inputs ie air conn and engine temp.
whether they would be man enough to cool the engine coolant.
if they were cooling engine coolant, what would they do to the air conn temp.

I spose it also depends whether yu have air conn or not to.

revjames · Aug 31, 2007

You would need a 2 way relay, and a temperature switch (ie opens at say 65 degrees and closes at 95) just a guess. There should be a sender for the temp gauge anyway but thats a variable resistance not an open/closed input. The 2 way relay would give you normal AC (lets face it if you need AC your engine will need cooling too) in one position and then a kind of override for the independent control of the fans for cooling. I never managed to get the circuit info off the guy, only saw him the once. he runs his disco like that and has no problems.

The Mad Hat Man · Aug 31, 2007

i am not sure how a/c works - but if the refrigerant is cooled by the cooling fans - switching them on unnecessarily wud reduce the refrigerant level below the required level - would it not?

If they are variable speed fans - that opens up a whole new nest of vipers - coz they might have feedback to an ECU.

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