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E36 M3 (1992-1999) {Euro - S50 B32 321hp @ 7400 rpm} {U.S. - S52 B32 240 hp @ 6000 rpm}
Total Produced: 71,212 - Years Produced: 1992 to 1999


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Old Tue, Mar-17-2015, 07:59:22 PM   #1
matty.
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Exclamation Potential Purchase - Help w/ Oil Pressure Light Flickering at Idle

I went to look at a sedan over the weekend. Need some feedback on an issue before I consider a purchase. Your insight is appreciated..

The car drove perfect. Temp that day was in the high 80's. Test drive only lasted 20 min or so. No lights or warnings the whole time. Car was allowed to idle before test drive while we talked for ~15 min so it had time to get warm. Upon return and coming to a stop to park the oil light began flickering. Then solid on, then flicker, and off. . so on and so forth. Normally I would shut the car down and tow somewhere to have it inspected, but I wanted the seller/ my friend to see the light and be aware that it just started doing it. Then we shut it down and confirmed that the dipstick was still showing full.

I understand others have had this issue with mixed results. Some said they experienced this with catastrophe shortly after. Others fixed with a new oil press/temp switch located on back of filter housing. Others said they felt it was normal and changed when a thicker oil was used, or that it was possibly a low battery/ low alternator output. To me this is not at all normal. Over the ownership of two prior e36 m3 sedans in nearly 10 years I've never seen this other than if oil levels are approaching low and I'm on a long right hand onramp.

To give some background on the type of seller/ vehicle. The seller is a friend of mine I've known over the past 10+ years. He is meticulous with all the cars he owns; several including a Carrera 4S. Record keeping and maintenance is 100% from day 1. Never raced or tracked. He's a bit older than me (which makes him really old). No kids, pets, accidents, stories, etc. Everything is just as it rolled off the showroom floor with exception of euro lighting (front & rear), new Zimmerman rotors & PFC pads, Dinan airbox. Car is always garage kept and covered. Single owner CA. car. It was typically only driven on Fridays & weekends so the miles are pretty low. Oil change every 5k. I'm not sure why but he liked using Mobil1 5w-30. Before the car was even started, the level was checked and confirmed at the full line. The car is always parked in the same spot so there were not any coolant or oil leaks visible on the garage carpet.

I'm not sure what to do at this point other than tell him to have a shop hook up a gauge and confirm the oil pressure at idle meets spec? He said he called his tech who told him its just flickering because the car hasn't been driven enough.. which didn't make sense to me?

I have had my fair share of things go wrong with a BMW once the transaction is complete and I'm on the drive home, so I definitely don't need to add a major engine failure to the list. . Does it sound minor enough to still consider or would you walk away from the sale??

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Old Tue, Mar-17-2015, 08:27:20 PM   #2
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Default Re: Potential Purchase - Help w/ Oil Pressure Light Flickering at Idle

I've experienced the same issue in my 97. Keep in mind that 5w-30 is thin for these cars, and the ambient temp was relatively warm. According to this thread, the owners manual mentions it's normal (haven't verified this myself):

http://www.bimmerforums.com/forum/sh...dle-after-warm

I would definitely get the oil pressure checked with a manual gauge before you buy it. If pressure is low at higher engine speed then I wouldn't buy it. Sounds like a good car otherwise, I hope it goes well!
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Old Tue, Mar-17-2015, 08:39:50 PM   #3
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Default Re: Potential Purchase - Help w/ Oil Pressure Light Flickering at Idle

might be the spec oil that is in it, but often people keep adding a higher weight oil to bandaid the symptoms.

It also could be as easy as a cracked pickup tube. My fathers car was sort of doing this (never light fully on though) and i changed to 15w50, kind of helped. I ended up pulling the pan and the pickup tube was broken, so i replaced it with the z3 reinforced version and baffle. Also kind of helped. Later down the road it spun a rod bearing while returning to idle on an off ramp.

Wouldn't hurt to change the sensor and have the pressure actually tested but i wouldn't take oil pressure lights lightly at all.
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Old Wed, Mar-18-2015, 02:40:17 AM   #4
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Default Re: Potential Purchase - Help w/ Oil Pressure Light Flickering at Idle

Mileage?
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Old Wed, Mar-18-2015, 03:07:36 AM   #5
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Default Re: Potential Purchase - Help w/ Oil Pressure Light Flickering at Idle

Definitely isn't normal. I'd have it thoroughly checked out before buying.
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Old Wed, Mar-18-2015, 03:19:04 AM   #6
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Default Re: Potential Purchase - Help w/ Oil Pressure Light Flickering at Idle

Definitely don't take lightly an oil pressure light that occurs at idle. You have to keep in mind that oil pressure in an engine is largely determined by the resistance to its flow to/through the areas that lubricate rotating internals. When a crankshaft/camshaft bearing is damaged, that's going to increase mechanical tolerance in the rotating assemblies which is going to allow oil to flow through more easily and reduce oil pressure. Oil pressure is inherently lower at idle as a rule, because the oil pump just isn't spinning as fast, which is why an oil pressure light at idle is most likely to reveal significantly worn internals and/or bearings.

In other words, the oil-pressure warning light sender might trigger at 15-30 PSI - which are conditions that are well exceeded when the engine is running at 2000 RPMs and beyond, but an engine in a bad state will not produce this pressure at idle. Driving the car more isn't going to fix something like this and I'd imagine any mechanic that told you that takes you for a country rube.
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Old Wed, Mar-18-2015, 03:25:22 AM   #7
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Default Re: Potential Purchase - Help w/ Oil Pressure Light Flickering at Idle

Not normal! 5w30 is just fine in these engines and others have said, thicker oil is just a bandaid fix. Pickup tube or oil pump nut. Both easy fixes but if it has been running on low oil pressure then who knows if and when it would fail
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Old Wed, Mar-18-2015, 05:34:13 AM   #8
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Default Re: Potential Purchase - Help w/ Oil Pressure Light Flickering at Idle

Quote:
Originally Posted by Jrrrrrrr View Post
Definitely don't take lightly an oil pressure light that occurs at idle. You have to keep in mind that oil pressure in an engine is largely determined by the resistance to its flow to/through the areas that lubricate rotating internals. When a crankshaft/camshaft bearing is damaged, that's going to increase mechanical tolerance in the rotating assemblies which is going to allow oil to flow through more easily and reduce oil pressure. Oil pressure is inherently lower at idle as a rule, because the oil pump just isn't spinning as fast, which is why an oil pressure light at idle is most likely to reveal significantly worn internals and/or bearings.

In other words, the oil-pressure warning light sender might trigger at 15-30 PSI - which are conditions that are well exceeded when the engine is running at 2000 RPMs and beyond, but an engine in a bad state will not produce this pressure at idle. Driving the car more isn't going to fix something like this and I'd imagine any mechanic that told you that takes you for a country rube.
If the oil was warm then the oil pressure should be low during idle, it should be at around 5-10psi. The light flickers on when there is no pressure at all. Definetl not normal and I would stay away from the car.
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Old Wed, Mar-18-2015, 05:25:01 PM   #9
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Default Re: Potential Purchase - Help w/ Oil Pressure Light Flickering at Idle

Quote:
Originally Posted by camdinans3 View Post
might be the spec oil that is in it, but often people keep adding a higher weight oil to bandaid the symptoms.

It also could be as easy as a cracked pickup tube. My fathers car was sort of doing this (never light fully on though) and i changed to 15w50, kind of helped. I ended up pulling the pan and the pickup tube was broken, so i replaced it with the z3 reinforced version and baffle. Also kind of helped. Later down the road it spun a rod bearing while returning to idle on an off ramp.

Wouldn't hurt to change the sensor and have the pressure actually tested but i wouldn't take oil pressure lights lightly at all.
+1

FYI, my engine felt strong until the moment I spun a bearing. Not something you want to set yourself up for if you can avoid it.

If you really want to buy the car, see if the seller will let you get an oil analysis done. That would go a long way towards indicating whether the bottom end is in trouble or not..
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Old Fri, Mar-20-2015, 12:39:45 AM   #10
matty.
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Default Re: Potential Purchase - Help w/ Oil Pressure Light Flickering at Idle

Quote:
Originally Posted by vmbray View Post
Mileage?
94k


Quote:
Originally Posted by Jrrrrrrr View Post
In other words, the oil-pressure warning light sender might trigger at 15-30 PSI - which are conditions that are well exceeded when the engine is running at 2000 RPMs and beyond, but an engine in a bad state will not produce this pressure at idle. Driving the car more isn't going to fix something like this and I'd imagine any mechanic that told you that takes you for a country rube.
Not sure what you mean, but as a rule pressure typically goes up 10psi: 1k rpm. So yeah running at ~3k should be around 35-40 with idle being around 7-12.

Quote:
Originally Posted by englishtom1596q View Post
Not normal! 5w30 is just fine in these engines and others have said, thicker oil is just a bandaid fix. Pickup tube or oil pump nut. Both easy fixes but if it has been running on low oil pressure then who knows if and when it would fail
Well BMW states that thicker oil is spec, printed pages from the manual says climates warmer than 58F should at least have a 5w-40. So it is possible that a water thin weight combined with a hot day could be responsible.

Quote:
Originally Posted by Rouzbeh View Post
If the oil was warm then the oil pressure should be low during idle, it should be at around 5-10psi. The light flickers on when there is no pressure at all. Definetl not normal and I would stay away from the car.
My understanding is oil pressure at idle is ~7 psi. The light will come on if pressure is below that value. What is your source for this info?

The car is immaculate and I don't think it's worth throwing away hope just yet. Looks like the issue is common across several boards. Sometimes serious sometimes not. Typical order of repairs are faulty sensor replacement. Drop pan confirm condition of pick-up tube. Confirm oil pump is in spec. Last is more serious engine issues.

For the record I've never liked Mobil1 5w-30 for anything but Hondas. I used it on my first m3 and my car drank it like water in the socal climate. Upped to 40+ weight and never had an issue again.

Thanks all for the input.
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Discussing Potential Purchase - Help w/ Oil Pressure Light Flickering at Idle in the E36 M3 (1992-1999) Forum - {Euro - S50 B32 321hp @ 7400 rpm} {U.S. - S52 B32 240 hp @ 6000 rpm}
Total Produced: 71,212 - Years Produced: 1992 to 1999 at BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)