Test using Compressor - Interesting
I just did something you might find interesting to tell the difference between IMG and HGF.
I disconnected the return line from the radiator to the expansion bottle, at the bottle end, and plugged it with a pressure gauge.
I then connected an air compressor to the expansion bottle where the return line would normally go.
Therefore this is like a pressure test of both the system and the cap, since the cap regulates pressure.
I found that the system went to 1.2 bar, and then slowly bleeds back to 0.8 bar, and eventually to zero bar.
However, the oil level on the dipstick goes up.
Meanwhile, doing this over and over so that 1 liter of coolant is lost does not produce anything in the cylinder when cranking without plugs.
Therefore, I know that my initial plan to replace the IMG Inlet Manfold Gasket will not actually solve problem,
it is a HGF between oil and water passages not involving the cylinder, as all compression check at 140 psi-ish.
Does anyone thing this conclusion is not valid, if so please let me know.
Also, when it comes to cleaning the system out, pumping in air in this fashion is a good way to forcible eject all the crap out the top of the rad.