Well many of you know, several months back, we overheated the Trooper and cracked the factory head, as many of us 2.6L owners do. We replaced it with a brand new AMC aluminum casting that has been working great since then.

However, just a few weeks ago, we noticed some symptoms begining to reappear... such as the surging at idle, etc. So we checked the radiator and found it had puked out over half its contents into the overflow container and the engine compartment.

So the troubleshooting began....
- we boiled the thermostat to make sure its opening. And I can tell it is by the upper radiator hose getting hot too.
- did a complete flush and fill on the coolant system. using the garden hose to completely flush out the radiator, the block, and heater core. no signs of blockage from any of those systems
- and finally, replaced the radiator cap with a brand new one
- oh and I should say, the temperature guage doesn't report anything abnormal while running the vehicle, if anything, I think it tends to read a little cooler than it should once warmed up.

Even with all that, after about 10-15 minutes of driving, it will gradually transfer the contents of the radiator to the overflow container. such that in about 10mins, the overflow will rise from the min to the max line.

Can anybody offer some words of encouragement? Where we should go next in our troubleshooting process? pressure test? dye? replace water pump (though its not weeping)?

-Rob