How many miles are on the car? Have you ever replaced the water pump? For the most part, they don't really wear out, there just a mechanical system that turns when the timing belt turns. As long as the bearings fail, they just keep going. I agree it could be a small radiator leak but it could be tought to find.
Have you done a tuneup recently? Cap, rotor, plugs, wires?
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Andy - Reinstated
Hybrid Forum Moderator
'06 Subaru Legacy Spec B - Stock, for now
'98 Civic EX - CTR headlights and grill, Kosei K1's, for sale
'90 240SX - SR20DET that will never get installed, project car.