If it was bled properly and the waterfall goes away but returns after driving for a while it sounds like head gasket leaking and gas getting back into the coolant. Definitely do a chemical test!

 

Thanks for your help everyone.

Say, Savannah Buzz - I bought one of those tests from Napa a while back - I'd seen you posting about it a lot. Thing is I couldn't quite figure out how to make it work with my Rover. Just a huge syringe-y thing with a bulb on it and some testing fluid. The exact one is here: NAPA AUTO PARTS

My coolant expansion tank is plastic - and coolant is continuously pumped through there via the neck of the cap while the car is running - are you familiar with this?

That design (with the constant stream of coolant) makes it impossible for me to perform the test without sucking coolant into the tester - thus contaminating the result.

Am I doing something totally wrong? Prolly - please let me know if there's a better way.

And thanks again!

 

You are supposed to suck up the coolant, that is what you are going to be testing.
The test detects exhaust mixed into the coolant.

 

Look for coolant on the garage floor after it is parked for an hour.
That will tell you you have a leak.

Ok try this.
When your truck is parked say 1/2 hour.
And, you take the cap off of the coolant tank slowly --
then does it blurp blurp and coolant comes BACK into it?

If so - replace the head gaskets.

 

preasure test your system as already suggested

 

Will a pressure test ID a head gasket leak?