Discovered that my 79 300D ( non turbo ) does not have the vent pipe from water pump housing to head as it should have according to the parts list. Could this explain erratic temperature fluctuations as I suspect that air pockets are forming in the engine due to cavitaion or whatever. Later Om617 ( +- 1983 's ) however did not require this vent pipe even thogh pump and housing remained the same - so I'm a bit puzzeled as to weahter one actually does need this vent.
Anyone have any info on this matter? Peter
