My 4L pushrod Ex, makes a noise like high presure air leaking through
a blown joint, this happens as the engine gets hot, say if standing in
traffic, only at tick over, goes as you rev the engine. The AC leaks a
little through the pump body, but filling once a year with a can and
gauge its Ok so don't think its that.the belt does not appear to slip.
I thought it may be the cooling fan viscous thinging but dowsing it in
WD40 makes no difference.
Any ideas