06/06/2026
Bmw 6 series cabrio
We attended vehicle at customers address, to carry out initial diagnostic.
We discussed fault with customer and they explained a high pitch squealing sound, high oil temperature, higher fuel consumption, engine misfire.
We allowed vehicle to run and warm up but fault didnt occur. We decided to carry out vehicle road test and within a couple 100 yards fault was present. We returned to customer address and started diagnostic process. Noise was present within the engine bay, high pitch squeal changed when engine revved or brakes applied.
We attempted to open oil filler cap but engine was creating excessive vacuum not allowing this, we then removed upper engine cover to access (pvc)positive crankcase valve/camshaft cover, a large vacuum could be felt here, possibly caused by failing diaphragm within component. The pcv valve is part of rocker/camshaft cover so we got a replacement order and fitted.
Customer had also mentioned misfire originally which the above could have been causing this fault also but this wasn’t to be the case. So we looked into misfire moving ignition coils between cylinders to narrow down and identify which one had failed.
This was also replaced and vehicle was ready for roof down driving in the glorious sunshine we had.