Perkins 4.108 Home Made Heat Exchanger

[MV-Romnya]

I incorrectly posted a thread in the plumbing and fixtures section of this forum about my Perkins 4.108 over heating but nevertheless got exceptional advice - In that learning process I found that I am missing one pipe to the Heat Exchanger also that the HX is home made.. where is the missing pipe? the cooling system is closed circuit There is a pipe from the header tank to top of the cylinder head which houses the thermostat then there is a pipe from the HX to the exhaust manifold which then flows to the bottom of the engine block. The Perkins shop manual states that there should be a 3rd pipe from the rear of the engin block to the HX and the existing pipe from the header tank only opens at 83`c - the only way I can see how my system works is that when the engine starts up the coolant is circulating in its self till the thermostat open and then the circuit begins - I've gained exceptional knowledge from all you good people and am yearning for more - help and comments please - I feel like Humphry Bogart on "The African Queen" - MVR