E300td 1998 cooling test & fuel pump

[nford]

Can you advise on what pressure to be applied when testing cooling system ? also there is a knocking noise from idle upto 1500 rev, then disappears,Ive been advised could be tappet, but having placed a stythescope on the fuel lies the knocking noise is emitting from fuel lift pump, any ideas / advise thanks

 

[dogsbody]

e300td 1998 cooling test

I usually apply between 12 and 20 psi to the cooling circuit to test for leaks. At this pressure I have found over the years several pinholed hoses, which were leaking enough water to show a daily change in the level in the header tank, but no other telltale signs as the water evapourated immediately. 15 psi will be enough to detect dodgy water pumps and similar.
Why do you ask the question - what is the cooling problem?

 

[nford]

Water leak

Thanks for the info, have leak from thermostat housing ,will replace o ring then test , any ideas on the knocking noise ?