Flushing route cache?

I have a linux host that is on the 2.4.20 kernel.
After I do some route manipulation, the host seems to
remember cached route values from before the route
table changes, and I cannot seem to get rid of those
entries with 'ip route flush cache'. 'route -C flush'
seems to exist as a command option, but is not supported.

If I delete the default route on this host and add it
back again, verbatim, the routing works as expected.

The issue I am seeing is that the host seems to be
trying to resolve the MAC address of the destination by
arping, instead of using the next hop defined in the
routing table.

Any pointers on how to make the routing table changes
take effect immediately?

TIA,

irax.