Nopainnogain445
Newbie
So I have a 1989 gmc k1500 and for the last couple weeks I’ve noticed my temp guage slowly creeps up once I get on the highway doing about 60-65mph to about the 230 mark and one I slow back down to 30-40mph the temp drops back to normal, I replaced the thermostat and water pump was replaced a couple years ago, the coolant that is in there is brown and there is buildup around the inside of the radiator, also I have no heat what so ever so I am thinking maybe it’s a clogged radiator and heater core but I would think that would cause overheating at lower speeds, any help would be much appreciated.