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Johnny 5C

Fan Comes On At Startup

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Hi guys.

My 4 pot M43TU is running nicely now, but I have noticed that the rad* fan kicks in about 20 seconds after starting the engine.

Nothing else is wrong. The temp needle is bang on 12 o'clock when warmed up.

Just seemed a little odd. Thats all!



*on edit. A fan comes on, is there more than one?

Edited by Johnny 5C
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Yes mate number 11. I got mine from c3 BMW spares (they used to be local to me in SE London but have recently moved to brands hatch. They do deliver). The sensor was about £15

Before changing that I tried a new fan, resistor box ect.

It was actually ian323sport on here that put me in the right direction of a faulty switch :)

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No didn't johnny. It takes hardly any time to change I think you either turn it 90 degrees then it comes out or you slide away a clip then it pulls out.

I bled the air out of the system after :) don't think there was much in it tho tbh :)

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Cheers chaps.

I need to replace the hose on the rear of the engine, so i will probably do these two at the same time as i will need to bleed the air out.

Im actually not that up to speed on bleeding the cooling system.. or particularly confident about it..

Edited by Johnny 5C
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Marc, done some searching, but what exactly is the process for bleeding the air out?

Mine doesn't come on at startup. If it does it must be on the lowest setting cos I've had my car for 3 years and never heard it!

The bleeding process isn't much :) It's fill up the expansion tank with the bleed screw out (there is only 1, on top of the expansion tank). Start the engine and put your heaters on 32 degrees but the lowest fan setting.

Wait till coolant comes out of bleed screw then put the screw back in.

I then took my car on a 5 min drive to warm the the engine up and the thermostat to open. When I got back I loosened the bleed screw 2 turns until coolant started coming out then tightened.

Jonny on your m43 what is your pipe like going from the thermostat housing to the top of the radiator? Mine is sucked in like there is a vacuum. It's been like it for ages I'm wondering if it's normal. I don't think it is!

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Marc, all my hoses are round. Could be just a kink in the hose rather than a vacuum. If you tool the rad cap off the vacuum would be released right?

I have just finished wrapping my trim in CF look vinyl. Put it back in and it looks awesome. I still have one of the aluminium fixing posts on the table though. So back out tomorrow to find out which one is missing.....

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Interesting link.

The car is supposed to run the fan for 20 seconds when you first turn the car on, then check to see if it is spinning, if the fan is not spinning the computer should set a code.

Going out in an hour. I'll let the Mrs start the car while I stand outside...

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OK, so the fan does go off on its own after start-up... hmm

As a distraction from my fail, here are some pics of my interior trim CF vinyl wrapped.

I need to slide the passenger side strip towards the radio to close the gap, but the result is awesome.

Just a tenner delivered for the wrap. I ordered 1000x750 black at 2 pm, and it arrived the next day from this guy:


Photos don't do it justice.




Edited by Johnny 5C
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