Well the original TF box is now rebuilt. Seems to turn nicely & the propshaft that goes to the front wheels for selection to 4WD, turns freely when it is in 2WD. So it is now installed again.
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But same trouble, oil is still being lost from the breather. Plan B was to tap a hole for an alternative place for the breather 2 inches higher up, with due regard to the architecture of the casting inside, it is a fairly sheltered from the direct squirting of oil from the gears. But oil is lost just as readily from this higher breather position.
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Although OEP220 is what was used in service as required by the Servicing Schedule, some have suggested that there is no anti-frothing agent in OEP220 but there probably is in an EP90.
This all sounds very reasonable. But I doubt if most privately owned Humbers get treated to OEP220, the owners will be using EP90 yet still they have breather leakage problems.
I am wary of using a thinner oil as this will increase wear, but was still thinking of an additive.
Looking at the Saladin Servicing Schedule new transfer boxes at the 500 mile service have OX320 added to the OEP220. So that it is present in 10% concentration.
OX320 is 90% mineral oil & 10% colloidal graphite. Anyone any experience of adding graphite additives in anything?