need to change my coolant sensor on my 2001 xk8... any idea how.........

 

The sensor literally plugs into the bottom of the surge tank. You can replace it without losing any coolant, as it never touches the coolant. It sits up inside a small well in the tank bottom. It is a reed switch, which operates by way of a float inside the tank. Generally, these dont fail as often as the float fails! A new tank includes the sensor, but it isn't exactly cheap. I suppose you could test the switch when you get it out by passing a small magnet near it (with it plugged in, of course) and see if the Low Coolant light goes on and off. Might take two people to do that. One in the car watching, etc! If you can turn the warning on and off, you likely need a tank. Way too much info, but I hope this helps!

 

The float inside the expansion tank fails more often than the sensor. Not sure about the magnet trick, but you can lift the float with a long screwdriver or piece of wire. Just don't force it.

With the engine cold, locate the float inside the tank before you start the car. It is on the side closest to the center of the engine in the back of the tank. Once you find it, start the car and lift the float If the light goes off, you need another tank.

They come with a new cap and sensor. About $150 and easy to change.

 

This link to my page will have the location and what it looks like.

Link JagRepair.com - Jaguar Repair Information Resource

 

My surge tank has a slight leak from the bottom of the tank. I haven't pin pointed it yet but it looked like it was coming from the level sw, but what I am reading it sounds like the sw has not direct access to the coolant. Is there other places on the bottom of the tank or the tank it self that has a tendence to leak?

 

Correct, the sensor switch does not touch coolant.

The expansion tank has been known to weep from the seams as the plastic ages, but start with the hoses. Both the rubber and the plastic can deteriorate over time. I had to cut back on one hose about a 1/4" to get it to seal properly.

And be careful, if it is the tube on the tank itself that is at fault, they can break off on you.

 

I had a tank that sprang a leak on the side nowhere close to a seam. Constant flexing under pressure, vacuum, near boiling and below freezing over many years is not appreciated by the little tank.