Oil pressure warning
12-08-2018, 07:09 AM
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Oil pressure warning
I have a 2008 bmw 550i and my wife was driving home last night when the oil pressure warning came on she thought it meant low oil levels so she drove it 2miles before getting home. This morning i checked the oil levels which were between min and max i started it up and engine still sounds good i turned it off and looked under the car and had a little puddle of coolant on the ground should i be worried?
12-08-2018, 11:49 AM
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I have a 2008 bmw 550i and my wife was driving home last night when the oil pressure warning came on she thought it meant low oil levels so she drove it 2miles before getting home. This morning i checked the oil levels which were between min and max i started it up and engine still sounds good i turned it off and looked under the car and had a little puddle of coolant on the ground should i be worried?
12-08-2018, 02:20 PM
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+1 ^^
I'd either swap in a new oil pressure switch, or test with an actual gauge connected to the pressure port. If she actually drove 2 miles with zero oil pressure, all kinds of bad could happen.
I'd either swap in a new oil pressure switch, or test with an actual gauge connected to the pressure port. If she actually drove 2 miles with zero oil pressure, all kinds of bad could happen.
12-08-2018, 02:42 PM
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12-09-2018, 07:13 AM
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In case you don't know, engine oil pressure rises as the engine speed does. Specification for oil pressure on an engine at operating temperature may be around 10psi at idle speed, and 60psi or so when running ~2000rpm and higher - oil pumps have a pressure relief that stops the pressure getting too high. Oil pressure llight switches can only tell you when there's less than about 5psi. Very worn engines (excessive crank bearing clearance) can have their idle oil pressure drop below the switch pressure, so the light can come on at idle, but it will go off again once you rev the engine higher as the pump overcomes the pressure loss due to higher pumping speed. If the light stays on at road speeds it's either a serious engine problem (no oil, defective pump), or a bad switch.
12-10-2018, 03:58 AM
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I hope that's all it is too.
In case you don't know, engine oil pressure rises as the engine speed does. Specification for oil pressure on an engine at operating temperature may be around 10psi at idle speed, and 60psi or so when running ~2000rpm and higher - oil pumps have a pressure relief that stops the pressure getting too high. Oil pressure llight switches can only tell you when there's less than about 5psi. Very worn engines (excessive crank bearing clearance) can have their idle oil pressure drop below the switch pressure, so the light can come on at idle, but it will go off again once you rev the engine higher as the pump overcomes the pressure loss due to higher pumping speed. If the light stays on at road speeds it's either a serious engine problem (no oil, defective pump), or a bad switch.
In case you don't know, engine oil pressure rises as the engine speed does. Specification for oil pressure on an engine at operating temperature may be around 10psi at idle speed, and 60psi or so when running ~2000rpm and higher - oil pumps have a pressure relief that stops the pressure getting too high. Oil pressure llight switches can only tell you when there's less than about 5psi. Very worn engines (excessive crank bearing clearance) can have their idle oil pressure drop below the switch pressure, so the light can come on at idle, but it will go off again once you rev the engine higher as the pump overcomes the pressure loss due to higher pumping speed. If the light stays on at road speeds it's either a serious engine problem (no oil, defective pump), or a bad switch.
05-24-2021, 02:12 PM
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My Ride: BMW 550i - M package
Model Year: 2008
Engine: 4.8 litre, 8-cylinder
Question of the day is....where is the oil pressure sensor/switch located? I've heard passenger side, under the vacuum pump. To change it...are you accessing from above or below? Lots of youtube videos but none on the 2008 BMW 550i with the 4.8L 8-cylinder. Bought a repair manual online but it doesn't have a diagram/image.
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