Oil in the water .
As ch7472 said head gasket or head
On a similar note, my Falcon temp guage was all over the place over the weekend. Engine seemed to run fine, but whilst standing still or in slow moving traffic the guage was reaching to the top. After pulling away and giving it some gas the temp guage would drop again big time, but would then creep up again at the lights.
I've taken a look in the radiator and the coolant looked quite rusty and foamy. So am presuming the radiator's playing up, or just has a backload of rust sitting in it, but I'm quite surprised the car would run as smoothly as it did after pulling away.
Any other possibilities? Thermostat shot? Or maybe the water pump's on it's last legs? Any advice would be appreciated.
The subject of this thead really caught my attention. My first thoughts were some kid poured something bad into the car. However, it turn out to be something entirely different. Sorry to post on something I know nothing about, but I just had to comment on the subject. I'll bet others clicked on this thread for the same reason.
Sounds like the exact symptoms I had when my head gasket blew. Eventually the coolant gets so think and gooey that it will overheat every time you try to drive it more than 5 mins. Once it gets to that point it is also very, very difficult to clean it all out.
Cleaning out the gunk....you can only do this once its fixed. An old boy once showed me a way with kerosene. put in a cup.....get it hot, and then flush with clean water...garden hose up a heater pipe with the other end blocked works well...with the car running for short periods.
Do this 3 or four times and it should clean it....failing that some of the speed shops sell a cooling system cleaner that would probably be just as good...read the label.
You mention you have replaced the engine with a c/o long block. still under warranty??? this is a warranty item as far as i can see (unless you didn't meet all the fine print)
I think I need to flush and see if anything returns. The current state is basically milky green/white now and not clear green with the cottage cheese as it was when it leaked all out.
If anyone thinks of anything else, let me know.
If it returns, I guess I'll have a shop test the fluid for gases.