Posted for "Gerard O Connell" <goconnell@dodo.com.au>:

 Matt,
 
 That is weird, there have been many complaints about the opposite problem,
failure of the pump to activate after a long flight and gear is selected down.
The concensus for this seems to be a leak from high to low across the dump
valve and is fixed by slightly loosening the dump valve in flight. The pump
usually begins running (if gear handle is left down and circuit breaker NOT
pulled as per check list). Have you tried opening the dump valve when this has
happened?
 
 I have observed marked pressure changes on my hydraulic guage with variance
in outside air temperature (up to 1800-1900 psi).
 
 Perhaps the solution is to leave the dump valve open whilst the airplane is
parked in hot conditions...??? I believe there is reference to this practice
on prior LML posts to avoid over stressing the hydraulics whilst parked.
 
 Tricky problem...
 --
 Gerard O Connell
 Melbourne, Australia
 VH-LPD (LNC2)