Chevrolet L27

The 3800 Series I — the first of the family the L36 finished, a 90° pushrod 3.8 of about 170 hp in the LeSabre, Park Avenue, Regal, Bonneville and the Lumina APV.

It is the same architecture as the Series II and not the same engine, which is worth establishing before buying a part: heads, intake and management all changed at the Series II, and a listing that says only 3800 covers both.

The fault worth knowing first is the fuel pressure regulator, because it fails in a way that reads as something else entirely. Its diaphragm splits, the vacuum line then feeds raw fuel straight into the intake, and the car runs black-smoke rich with a fuel smell and no obvious leak. Pull the vacuum hose off the regulator and look for petrol in it — that is a thirty-second test that settles a diagnosis people spend a day on.

The other recurring items are the ignition control module and its coil pack, which fail as an intermittent no-start or a stumble that comes and goes with heat, and the crankshaft position sensors behind the balancer.

And it shares the GM-wide intake manifold gasket, the same composite gasket the 3.1, 3.4, 3.8 and 4.3 all use, which works loose as the engine heats and cools until coolant finds a way out — or into the oil.