Low Oil Pressure and Rod Knock After High-Speed Driving - 7M Engine Rebuild with Oil System Upgrades

Engineadvanced✓ OP Confirmed

Problem

After sustained high-speed Autobahn driving (230-240 km/h), the engine developed noticeably louder startup knock and reduced oil pressure, with a diesel-like knocking sound under load between 3000-3500 RPM.

Loud knock for first second after startup until oil pressure builds (worsened after high-speed driving)Oil pressure dropped from ~2.8 bar (40 psi) at 3000 RPM to 2.0 bar (30 psi) at 3000 RPMOil pressure reads 1.6 bar (24 psi) at 2000 RPM warmDiesel-like knocking between 3000 and 3500 RPM under load

Root Cause

Worn rod bearings, likely caused by a previous owner driving with a bad head gasket (coolant contamination in oil damaging bearings). The existing bearing damage was worsened by sustained high-speed/high-load driving at 230-240 km/h on the Autobahn.

Confidence

Moderate confidence — Original poster confirmed this resolved the issue

View Original Thread →Posted August 2020 on SupraForums.com