Want to fit a manual over-ride switch for radiator fan

M

Mickey Dale

True Classic
Hey guys,

Had to drive 80 miles yesterday on motorway. Car ran great until I came off motorway and temp started to rise quite alarmingly. The radiator fan refused to come on at all. I leaned across the drop the fuse panel and see if I could make it burst into life, but no joy. Then the guy behind me knocked on my window and said I was leaking fluid. I managed to pull over and noticed some horrid rusty coloured water coming from the small overflow pipe on the expansion tank in the engine bay.

I'm going to totally flush the system. The expansion tank looks like it has thick sludgy crap in the bottom of it. Not nice. And I will make sure the fan is working right. But I would like to fit a manual switch on the dash too. I searched for threads relating to that but had no success finding out how to do it. Could someone please point me in the right direction?

Final question...

Once the car cooled, I thought I'd set off and complete the last two miles of my journey to Liverpool. Turned the key. Nothing.

I have done the brown wire mod, the ignition switch is all good. Earths are good all round. This problem has happened before and it's always when the engine is warm. Not even a click form solonoid. I'll start by pulling the wires and cleaning them all on the starter motor. Other than that, are there any common things which cause this that I have not yet covered?

Have a great weekend folks! Thanks in advance of any help!

Best,

Mickey

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Easy to do

You can do this without cutting any wires too... and it's EASY.
Just find a short pigtail that has male/female connectors on the ends that match
the radiator thermal switch.
Then run a pair of wires from an unused console switch to the front, near
the radiator switch, (sensor) and ACROSS the pigtail. (essentially shorting out the pigtail)

It's not important that the wires be a large gauge. 16Ga will work fine.

Then, insert the pigtail BETWEEN the radiator thermal switch and the wire that it connects to.

Warning: Do NOT insert this in-line with the FAN wire. These connectors, unfortunately,
are the same. Doing so will only blow the fuse for the fan when it comes on.
 
Another option...

Since the thermo switch in the radiator grounds the radiator fan relay, you could also just put a parallel switched ground circuit to the radiator fan relay in at the relay in the fuse panel which will use less wire, among other things.

However, from your description of the overflow, it sounds like your flush plan will be the fix. A "hot no-crank" condition can be caused by any bad connection in the circuit, including internal ones in the starter. Be sure to clean and tighten all ground path connections.
 
and...

if you are purging the system, may want to order a new thermo switch ahead of time since it screws into the radiator....
 
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