On my 04 I have a weird thing with the coolant level. It will go down way below the normal level about even with the nipple that goes to the TBH . If I fill it up it will get pushed out by pressure through the overflow onto the frame rail. The main hose does not get hard with pressure and its been doing this for the 2 years that I have had it. All my others run about 1 inch below the full line . Any ideas what the issue is?

 

I have thoughts:

1. You have an air pocket in your heater core
2. T-stat is not opening and closing properly allowing back pressure
3. You have a clog in one of the hoses, possible heater core

 

Buy and install a new reservoir cap. About $15 at any auto parts store.

 

 

2nd the cap. And bleed the system after you do the grueling install.
.......

 

Hey have you ever found out what caused your coolant level to drop to the same level all the time? I have the same issue; not sure what is causing it. Thank you! --mc

 

It was an external HG leak at the rear of no. 7