Fan override switch

[billybradshaw]

Afternoon all,

I'm off to France later this year and I want to cover all basis in terms of limiting the chance of overheating.

I have fitted a new ali rad, new hoses, refurbed pipes, thermostat, temp gauge and senders.

I have bled the system and it all appears to be working well with the fans kicking in, etc. etc.

I can't help thinking though that for absolute piece of mind that I should wire in an override switch. I have been stuck in traffic queues in the heat of a French summer before and they're not much fun and I suspect with an AJP V8 up front my nerves will be shot to pieces.

So, as I am an electrical numpty, see my previous threads, would one of you be good enough to sketch a wiring diagram and suggest the components that I would need to make something up.

Ta very much

Ian

[aide]

Not sure an override switch would make much difference under normal circumstances.
If it's hot the ecu will cycle the fans anyway.
If it's cold you don't need them.
And when you're stuck in traffic, and the engine is idle, the water isn't being pumped efficiently.
So air flow from the fans - via the ecu or an override switch - will only cool slow moving coolant.

The best mod to get is a cooling chip from Julian Lane at kitsandclassics

[DCerebrate]

You could test on a hot day on the M6 at rush hour! New rad should help, but cooling is either adequate or not. As I had issues with coolant temps at idle with my Sp6, I went for Davies Craig piggybacked electric pump, and a single 16 inch high power pacet fan, with custom made cowl. High power twin replacement fans would do just as well though you would have to consider current draw. I found that the standard fans were only stirring the air, by comparison the high flow item is powerful enough to pull air through both the aircon and coolant radiators.

[billybradshaw]

I've been in touch with Joolz and a chip will be in my grubby mits next week.

I'll see how that goes, hopefully I won't need anything else with everything else being new / refreshed.

Ta

Ian

[FarmyardPants]

If you've replaced the hoses very recently make sure you check/nip up all the hose clips. Just sayin'

[billybradshaw]

FarmyardPants said:

If you've replaced the hoses very recently make sure you check/nip up all the hose clips. Just sayin'

Yeah thanks for that. I noticed that a couple had started to weep. It's as if Silicon 'relaxes' a little which then affects the seal. I've used Mikalor clamps too in most places and I hoping that these will prove to be better than the conventional jubilee clips.

Ta

Ian

[Juddder]

aide said:

Not sure an override switch would make much difference under normal circumstances.
If it's hot the ecu will cycle the fans anyway.
If it's cold you don't need them.
And when you're stuck in traffic, and the engine is idle, the water isn't being pumped efficiently.
So air flow from the fans - via the ecu or an override switch - will only cool slow moving coolant.

The best mod to get is a cooling chip from Julian Lane at kitsandclassics

Just a question on this...

The cooling chip alters the temperature that the fans turn on, afaik, so is basically the same as turning on the fans manually, but just earlier at a lower temperature?

I was chatting with Mikesr about this a while ago, who did most of the disassembly of the ECU code to find out how this works, as to where in the ECU code the changes are made, and his feedback was

"The fans are switched on by the ECU which uses a separate electrical temp sensor. Plugging a laptop in and checking the temp the ECU is reporting will give you a feel for how high the guage reads above actual temp.

The ECU as standard turns the fans on at 95 and 97. The stat opens at 85/86 so the cooling system hots up another 10 degrees after the water is going through the rad before the fans kick in."

...

"These are 1 byte locations and if I remember correctly the temperature value is just stored as 1 byte HEX equivalent
xxxx is probably the on temp and xxxx is the off temp. We always set the off temp e a couple of degrees below the on temp"

[tofts]

Yes, thats all the chip does. I was going to have a look at the code myself at some point for this very reason, its just one of those jobs thats not that important.

Anyway, I also see no reason an over-ride would be a problem if your concerned. It would do no harm, but if the engine is working correctly then it should not technically be necessary. Not only this, but with the new tuning chip it does make a noticeable difference in the temperature and I have never had issues with mine with this chip fitted.