Turbo coolant line blew, and engine got pretty hot (knocking, etc.). Replaced line, and engine now runs hot after about 15 minutes of driving.

1) No sludge or water in oil
2) Cooling fans run normally
3) Top radiator hose gets hot- thermostat replaced 12 months ago
4) No smoke or funny odor from exhaust
5) Runs and idles fine
6) Coolant has no sludge
7) After 50 miles, still getting bubbles from thermostat return line (to expansion tank). More throttle = more bubbles.
8) When it gets hot, coolant comes out around exp. tank cap (cap about 12 mos. old)
9) Stop and let the motor cool down, and it's low on coolant again
10)When it gets hot (last white bar on gauge), the temp will drop at stop lights
11)I think it may have blown a head gasket when the turbo coolant line split

Comments??