QuestionThe upper radiator hose is hot, the temp. gage is red line within minutes, but the heater blows cold and it bubbles at the reserv. Could this be contributed to a faulty thermostat instead of a bad water pump.
AnswerHector,
I would, definitely, replace the thermostat right away as this is an inexpensive fix, and even if the water pump went out, the thermostat should be replaced anyway.
If the water pump is completely out, it should be leaking, or making a growling noise at the least.
The water should circulate a little even with a bad water pump due to the change in temperature from the radiator to the block.
Carl
