1989 Plymouth Sundance excessive oil loss & excessive e

Holy cow. That's worse than bad fuel mileage!

Hi originalalleycat. Welcome to the forum. This is much too much oil usage to be related to rings or valve guide seals. I would suspect a cracked head or a head gasket leaking between an oil feed passage to the head and a cylinder. Consider performing a cylinder leakage test to see if you can identify a single cylinder as having the problem. This involves placing one piston at a time at top dead center on the compression stroke, then forcing in regulated compressed air through a tester that will indicate the percent of leakage. Next, you listen or look in four places for escaping air. In particular, air escaping from the tail pipe would indicate a leaking exhaust valve. From the air filter / throttle body is due to a leaking intake valve. Bubbles in the radiator are from a leaking head gasket or cracked head, and a hissing from the oil fill cap or dipstick tube is from worn rings. Air being pushed back into the oil circuit is a little trickier to identify. If you have an oil pressure gauge, turn the ignition switch to "run". If the gauge rises during the test, suspect the head or head gasket. You can also remove the sending unit and watch for oil or air escaping from the port during the test.

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