df 70 looking for a miracle

[hadaveha]

my 1999 df 70 is killing me, after motor is started and runs for maybe 3 to 4 minutes i get 1.5 second beep every 7 to 8 seconds, seems to getting hot 210 dead center of the exaust manifold with my temp gun. new water pump, new tstat,new water valve, motor flushed with salt away, and flushed with pressure. water seems to be flowing freely with no restriction. I am at a compleet loss was going to pull the head but when we flushed it and the water seem to move so freely im thinking this is not the problem. I would be so thankfull for any help even if its bad help right now.
david

[Ads seajay]

Be sure to check the internal anodes throughout around the block. You may have one or a few in and around the block.
It sound like a similar issue to a problem I had with a second hand df40 that is of the same age. I ended up having to chip away at all the calcium build up that was blocking a water jacket around a exhaust port.