Posted: Feb 13, 2006 1:08 PM
Problem: Oil pressure light on the dash flickers intermittently but the oil level is fine.
Cause: Most common: Failing oil pressure sender switch. Less common: Internal engine oil circulation problems including worn out pump, passage blockage, or banjo bolt fell out of oil spray bar above the cam (M30 only).
Description: Although this could involve a serious problem, more often, it's the cheapest and easiest fix: the sending switch that's screwed into your engine.
How can you tell?: As well as the intermittent flickering that may bear no relation to engine speed (revving with a worn pump usually raises the pressure enough to get it to go out), look for a telltale trace of oil from the switch itself (on the rear of the head on an M30; down under & dirty for the M20) because they often leak, as well. It costs under $10 to buy one of these and takes under 5 minutes to change it. It's easier than an oil change! The second easiest fix involves pulling off the valve cover, so you're a fool if you don't simply replace this switch first. If you've fixed the banjo bolt and pulled the pan to rebuild your oil pump and then discover that it was only the switch, you'll really be pissed!
The Solution: Go to your nearest auto parts store (or dealer, if you insist) and buy the replacement switch. The guys at AutoZone won't believe they have it in stock, but they probably do. The replacement isn't any better - or worse - than the OEM part which very commonly fails. Fortunately, they're cheap and easy to replace: unplug the electrical connector and unscrew it. Screw the new one back in (I like to use Teflon tape on the threads) and plug it back in. If the problem isn't solved, start saving up your spare change ...
Cause: Most common: Failing oil pressure sender switch. Less common: Internal engine oil circulation problems including worn out pump, passage blockage, or banjo bolt fell out of oil spray bar above the cam (M30 only).
Description: Although this could involve a serious problem, more often, it's the cheapest and easiest fix: the sending switch that's screwed into your engine.
How can you tell?: As well as the intermittent flickering that may bear no relation to engine speed (revving with a worn pump usually raises the pressure enough to get it to go out), look for a telltale trace of oil from the switch itself (on the rear of the head on an M30; down under & dirty for the M20) because they often leak, as well. It costs under $10 to buy one of these and takes under 5 minutes to change it. It's easier than an oil change! The second easiest fix involves pulling off the valve cover, so you're a fool if you don't simply replace this switch first. If you've fixed the banjo bolt and pulled the pan to rebuild your oil pump and then discover that it was only the switch, you'll really be pissed!
The Solution: Go to your nearest auto parts store (or dealer, if you insist) and buy the replacement switch. The guys at AutoZone won't believe they have it in stock, but they probably do. The replacement isn't any better - or worse - than the OEM part which very commonly fails. Fortunately, they're cheap and easy to replace: unplug the electrical connector and unscrew it. Screw the new one back in (I like to use Teflon tape on the threads) and plug it back in. If the problem isn't solved, start saving up your spare change ...