The 3.8 engine was a GM wonder. They toyed with this motor, changed things for many years. Untill it started lasting too long. Then it was discontinued.
As stated they last many miles. Most are just getting broken in at two hundred thousand.. Most never see more than 3200 rpm. Cruise at under 2000 rpm. The only problems they have is intake plenums/gaskets and head gaskets. Usually at higher miles. This example probably spent a lot of time on I-75 and I-94 racking up the three hundred thou miles in comfort.
These are not 56 Chevrolet engines. They don't have fancy coatings on the valvetrain. It is just GM got it right, finally. Thin rings that don't beat up the ring lands, conform to the cylinders better. Light weight valves and springs. Positive oil controll seals. Fuel injection and OD tranny.
You will usually find the leak is on the back head. Drivers end. Between the coolant passage and the fire ring of the last cylinder. It Brinnells into the casting from heat cycling. Usually only leaks, into cylinder, at running temp at higher speeds.
You can have any auto repair place put a tester on the cooling system. You may be able to rent/borrow a tester from a chain auto store.
Last edited by BOBCRMAN@aol.com; 11-01-2012 at 08:37 PM.