Recently our oil pressure light has been flickering = and sometimes staying on steady for seconds at a time. I have = checked the pressure by pulling the 0.3bar switch and installing a = pressure gauge. I have 7-8 psi (0.48-0.55bar) at idle and = 30-40psi (2.00-2.76bar) at 3000RPM. I have noticed the light = flickering both below and above 2000RPM. The light is never = continuous above 2000RPM and the low oil pressure buzzer never sounds = not even a short BZZT.
Another bit of information is that I run 20W-50 = during the summer months and 10W-40 during the rest of the year. = If I wait too long in the spring to change over this problem = appears. The problem also arises during the summer if I have been = driving for extended periods of time when ambient air = temperatures are at or above 95 degrees.
Last summer I had our mechanic replace the 0.9bar = pressure switch. I understand that VW also has a 1.8bar switch = and that this switch is sometimes installed by mistake. If my = mechanic installed the 1.8bar switch this would explain why this = problem appears when the oil viscosity is too low either due to ambient = air temperatures or viscosity breakdown due to high temperature = duty. But if this switch is the cause then why is the oil light = illuminated below 2000RPM? And, why don't I hear a sound out of = the oil pressure warning buzzer above 2000RPM?
My other theory is that the wire going to the 0.3bar = switch is grounding out someplace. This would create a momentary = oil pressure fault for what ever duration the grounded condition = existed. This would explain the illuminated oil pressure light = below 2000RPM but not above. As I understand it the 0.3bar switch = input is ignored above 2000RPM. Has anybody confirmed this by = grounding the switch and running the engine above 2000RPM? If a = grounded wire is the cause of our problems then why does changing the = oil temporarily eliminate the problem?
Thanks in advance,
Tom Moritz