Practice question

A school bus diesel has low engine oil pressure at idle when hot but normal pressure at speed. The MOST likely cause is:

  1. A plugged cabin filter
  2. A loose lug nut
  3. A faulty windshield wiper motor
  4. Worn bearings/oil pump wear or a weak oil pressure relief, allowing pressure to drop at low speed and high oil temperature

Answer: D — Worn bearings/oil pump wear or a weak oil pressure relief, allowing pressure to drop at low speed and high oil temperature

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Practice more: ASE S2 Diesel Engines (School Bus) Practice Questions - ASE S2 - Diesel Engines (School Bus) Certification Exam →