Thank you Tom .
Allways a pleasure to read your comments.
Im sadly in lack of the necessary "McGuyver-Gen"
and im allways to fast in spending the bucks...
I tried a "radiator-cleaner" (whatever this is)
I tried vinegar-type-cleaner with no effect
Then i read your Threat (somewhere some weeks ago)
and used degreaser which took the grease away and
brought a fresh smell
Had to rinse about 10 times untill taste changed
to "normal water". I got a temperature-Gun but from
my point of view the difference in temps (Top-to-Bottom)
wasnt as high as expected and some dry-crusty-dirt is still
visible (Water stays clean even driving all day.....)
I didnt have the idea to look for cold spots with the gun.
Thank you again.
Will try even daytime-temps now are low over here.
For sure i will try a radiator shop too as my radiator looks great.
(Due to transportation and taxes, prices for US-Model-"A"-parts
are more than duplicated till i hold them over here ).
Best Regards Christoph