1999 Cadillac Deville. Digital coolant temp reading on the dash perfect at about 190 degrees. If I sit at a long red light or just creep along in a traffic jam, the coolant temperature will go as high as 220-224 degrees. Is this normal? How high can the coolant temperature get before I need to worry about blowing a head gasket?
It could be normal. As long as there is no message of engine overheat. The characteristic of a Northstar is not necessarily a head gasket blowing, but much more a condition of the threads in the block failing causing lost clamping force and internal leakage. Make sure your cooling fans are coming on, at a minimum when the A/C is requested, and also at the higher coolant temps.
May, 4, 2011 AT 1:00 PM
That would be completely normal. The electric cooling fans aren't programmed to come on until around 226 degrees. As long as the temp responds to the fans, you are fine.
May, 4, 2011 AT 4:45 PM
You need to watch the temp. On the dash. It will go to 220s then u will see it start going down when the fans come on. When the temp. Is low enough they will turn off. When you see the temp. Go back to 220s they will turn back on. The heater core could be leaking. The a/c case has a drain its got a rubber hose coming out of the a/c case. Its right below the evaporator. Check it for coolant leaking. Gl