87 4 runner overheating/no heat

i had a blown head gasket in my 22re 4runner. i replaced the whole top
end. new head, new cam, new valves. everything went fine for like 3
weeks and now its overheating badly. there is no coolant in the oil
and no oil in the coolant. truck runs good forlike 10 mins and then
the temp guage shoots up to red and the overflow tanks boiles. the
doesnt work either. can somone please shine some light on this
problem. i realy dont feel like having to replace a bottom end now.
email me if you have any ideas. thanks.