Originally Posted by
mox
Seems to me this should be used just for short term fix, not longer term in hot and heavy load conditions. With this heater turned off, water still should flow through the element. Note how reported damage to 300Tdi's from overheating seems to occur first around No 4 cylinder. Not a good idea to reduce or stop coolant flow there. Water obviously would not circulate past it as much in the head with heater circuit blocked off with these plugs. Would also be slowed by partially blocked element. So the solution as proposed by 86mud is preferable. Or as I had when heater was removed, one piece of three quarter inch standard heater hose connected to the fitting on the head, doing three quarters of a loop and the other end connected to the return pipe.
Effectively same result but probably easier to obtain bits to achieve it than 86mud used. No need to wrap tape around fitting in head of mine. Standard 5/8"" diameter to fit into special hose and with 3/8" BSP thread had earlier been replaced with more sensible standard one which fits 3/4" hose. The outlet hole in cylinder head has been bored and tapped to take 1/2" BSP. (Note that British Standard Pipe sizes are the approximate diameters of the pipe bores. Diameters of where threads are is much larger and these are the measurements that are critical.)