: Northstar drinking coolant - need advice

06-10-05, 12:26 AM
My 1996 STS with 170,000 miles has taken to drinking coolant. In the last week I drove about 400 freeway miles and needed nearly a gallon of coolant to top off the reservoir. This car has always used some coolant but now its going fast. No leaks to be seen anywhere. Can this be anything but a blown headgasket?? Car runs great. Mechanic is testing coolant for exhaust gases. Is this a surefire way to determine a headgasket problem, or should one pressure test the cylinders?

If it is a blown head gasket, what should I do? Fix the existing engine, find a used engine to replace it, or junk the car and get something else? My mechanic seems pretty spooked about doing the heads on a Northstar.

06-10-05, 01:20 AM
If your headgasket is blown it will show up in the coolant. You might be losing coolant through the overflow (defective cap) or from over-heating (waterpump). If you do find its the headgasket it is worth replacing, but make sure you time-sert the block while your in there. If you do this than you should be good for a while...

06-10-05, 04:04 AM
To test the head gasket, put compressed air in the spark plug hole and see if it comes out the coolant reservoir. There are tons of posts on this subject. I'm not sure of the exact procedure, but it is covered many times in this forum. This is a good one, but will take some time to pore over: http://www.cadillacforums.com/forums/showthread.php?t=32287

Good Luck!

06-10-05, 10:50 AM
Testing for exhaust gasses could be deciving. If the leak is at an intake port, coolant will be sucked out rather than at an exhaust port where exhaust gasses will be introduced into the coolant. If it turns up negative, you might want to do the cylinder pressure test to confirm it. The coolant has to be going somewhere and if there are no leaks then the assumption is that it is being injested.