I will be replacing the coolent temp sender on my L98 here shortly. Should i expect a lot of coolent to come out? Will i have to bleed any air out of the system after i replace it?

 

The coolant will spill out at a pretty good clip, but if the coolant is cold and your quick you can do it on the fly, just put a drain pan under the car.
refill with a 50/50 mix, let the engine run to operating temp, if you need to add more after, add it to the reserve bottle.

 

If you drop the level down to water pump level with the radiator drain plug nothing will come out

 

I just did this tonight. And just to be clear, you're talking about the SENDER in the head, -For the gauge, right? The SENSOR for the ECM is in the manifold.

Engine was cold but I had a little pressure anyhow. Nothing dangerous, but it shot all over the frame rail ...I lost about a quart. ...nothing major. just a little refill.

 

Helps some to pinch closed the hose from the rad. to the overflow tank, air locks the system and slows down the leakage some.