ASE A1 Engine RepairCylinder Head and Valve TrainEasy
A technician is performing a visual inspection of a cylinder head after an engine overheat event. They notice slight discoloration and a faint wavy pattern across the sealing surface. To determine if the cylinder head is suitable for reuse, what is the most appropriate measurement to perform?
- ACamshaft journal diameter with a micrometer.
- BCylinder head flatness using a straightedge and feeler gauge.
- CValve guide clearance using a dial bore gauge.
- DValve spring installed height with a ruler.
Show answer & explanationAnswer & explanation
Correct answer: B. Cylinder head flatness using a straightedge and feeler gauge.
Discoloration and a wavy pattern on a cylinder head's sealing surface after overheating strongly suggest warpage. The most appropriate measurement is to check the head's flatness using a straightedge and feeler gauge to ensure it can seal properly against the engine block.
Why the other options are wrong
- A. Camshaft journal diameter is relevant for camshaft wear, not for assessing cylinder head warpage after an overheat event.
- C. Valve guide clearance is important but not the primary concern for a cylinder head that has potentially warped from overheating.
- D. Valve spring installed height is a critical measurement for valve train performance but unrelated to potential head warpage from overheating.
Cylinder Head Flatness
The degree to which the cylinder head's sealing surface is free of warpage or distortion, critical for proper head gasket sealing.
- Measured with a straightedge and feeler gauge.
- Crucial for head gasket integrity.
- Overheating can cause warpage.
- Exceeding specifications requires machining or replacement.
Memory trick: Overheat's wavy, check the flatness, gravy.