Melandre wrote:
It takes a couple of minutes to get passed "normal temperature". Then
another minute or so to climb over 200F. Then stays hot for 1 to 3
minutes (in a few occasions a bit longer than 3 minutes), then it
drops back from well over 200F to 150F in about 3 - 5 seconds.


We can be very certain that the cooling system isn't actually dropping
in temp for over 200F to 150F in 3-5 seconds. If you're getting a
report of a condition that seems virtually impossible, one of the first
things to check is the data itself. You sending unit is almost
certainly a screw-in unit with a wire attached to it. A new one would
be very inexpensive.



I am not sure what you mean by "sending unit" but if you suggests that
perhaps only the readout on the dashboard is screwed up, I doubt it
because, for these few freaky minutes, I can really tell the engine is
overheating (burning oil smell, block starts smoking a bit). Or
maybe you are referring to yet another part that I am not aware of...

It is also a simple raw water cooling system (not a closed one with
coolant).

Andre