Yukon 2WD V8-5.7L VIN R (1997)
Exhaust Manifold: Testing and Inspection
1. Clean the exhaust manifold in solvent.
2. Inspect the gasket surface for damage.
3. Measure the alignment or surface flatness of the exhaust manifold flanges, using a straight edge and a feeler gauge.
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Flatness: 0.05 mm (0.002 inch)
4. If the flanges or the mating surfaces do not align, the exhaust manifold is warped and must be replaced.