NEED HELP! Coolant Leak

[RJ93]

When I changed my oil last time I noticed my coolant reservoir was empty, opened the radiator cap and it was not visible. I filled up the radiator with 50/50 and also the reservoir. A few weeks later (Today) I popped the hood and the reservoir was bone dry again, opened the radiator cap and it was once again not visible. I filled the radiator up but this time left the reservoir dry. I drove about 45 miles afterwards. Took off the radiator cap later that evening and the coolant level had dropped about 4 inches.

I hear the pressure release when I take the cap off. I do not see any coolant on the drive way.
I got under the vehicle and noticed fresh coolant-
1. On the lower radiator hoses
2. On parts between the fan and serpentine belt
3. Front, Side and bottom of oil pan, on the oil filter.
4. On the exhaust pipes behind the oil pan.

The bottom of the oil pan is also white wear I'm guessing coolant has dried. The temp gauge on the dash does not show overheating either.
I have no clue where to start, here are some pictures to hopefully help.

https://plus.google.com/102011793706945323853/posts/J9ggoXkGzgo

 

[drdoom]

Which engine?

 

[drdoom]

The SOHC engine thermostat housing is infamous for cracking, of course you want to look at the water pump as well.

 

[RJ93]

Which engine?

4.0L SOHC

 

[RJ93]

The SOHC engine thermostat housing is infamous for cracking, of course you want to look at the water pump as well.

Would I be able to check both of those on my own without taking it to the shop.

 

[XLTrunner]

A thermostat housing leak can be tricky to identify. Before I was educated about these t-stat housings leaking, I had taken it to a shop where they told me it was a head gasket leaking when I asked them to do a coolant pressure test. What I did was shine a flashlight (better when it's dark outside) to look behind it and into the forward part of the top of the engine valley. You'll usually see green coolant having pooled there.

Hoses and water pump are usually pretty easy to identify.

 

[RJ93]

Wouldn't the belt be squealing if the water pump was going out?

 

[drdoom]

No, first place to check water pump is it's weep hole, view with a mirror or get underneath.