2007 Chevy Silverado Classic 1500 LT, 5.3 Flex fuel, 4x4. 225k miles
I’ve noticed a slow coolant loss since I bought this truck 2 years ago, about a quart between oil changes at 3k intervals. About 6 months ago, one of the QDs (quick disconnects) broke off the heater core and I thought that must have been the problem. It appears it wasn’t.
When the QD broke, I replace all the hoses, QDs, Y’s, water pump and thermostat. Still losing coolant at the same or slightly higher rate. I was worried that it might be a head gasket, and since I don’t have a maintenance history on the vehicle before I bought it, I decided to go ahead and replace the spark plugs and see if there is any evidence of coolant in the cylinders. I don’t see any but looking for a second opinion.
Spark plugs are in order as viewed from the drivers side of the engine.
I get a LOT of condensate draining from the AC so the heater core is my next suspect. I don’t see any coolant in it but it would be very diluted. Can’t find evidence of leaks anywhere else.