Oil Pressure PSI in 99 M3?

[Zeppelin420Fan]

What does the normal oil pressure run at in psi for a 99 M3? I am asking because my father is looking at a miiinnttt 99 two door. The M3 has the aftermarket 3 gauge reader (oil psi and temp, and volt meter). The only problem was that the guages weren't working 100%. There seems to be a bad ground on the volt meter, and every once in a while the oil light on the dash would flicker on and off, and the PSI reading on the guage would fluctuate when this happened. It was explained that the oil pressure guage is piggy backed off of the oil pressure sensor.

cliffs: standard oil pressure psi on a 99 m3 coupe?

[Mad Dog 20/20]

min at idle is 7psi. below that and the light will come on. A flickering oil pressure light and/or low pressure at idle is not uncommon.

I seriously doubt the aftermarket pressure gauge is "piggybacked" off the OE pressure sender. Usually, there is a seperate sender mounted in the oil filter lid or in an oil distribution block mounted where the OE sender used to mount.

[Zeppelin420Fan]

7psi?! Im pretty sure it was reading anywhere from 25 - low 30s... The owner said it was piggy backed

[thejlevie]

Assuming an OE pressure switch, it does trip at 7psi. The oil pressure warning light should not flicker at idle unless the wrong oil is used, the filter is clogged/bad, the oil pump is leaking, the sensor is bad, or the engine is worn. Adapters are available to allow an oil pressure sensor and oil pressure switch to be connected to where the oil pressure switch normally mounts. So they can be piggy-backed. And oil pressure sensors are available that combine a warning switch and a pressure sensor.

[Zeppelin420Fan]

It wasn't even flickering at idle. It would flicker randomly even while driving.. I actually only saw it flicker on one occasion when test driving, and it was when he was slowing down taking a turn... But the owner said it was due to it being piggy backed, and drawing off of the original sensor or something..

[284Shooter]

Did you check the oil level?

This could be a bad ground. That's best case scenario.

Piggyback? I don't think the oil switch for the idiot light will send the correct signal to run one of those VDO gauges. My bet is he has a "T" in the block and the pressure switch is on one side, the oil pressure sending unit on the other. If BOTH gauges are fluctuating at the same time, that sounds like the oil pressure is dropping. It could be the oil pump nut is backing off or something is covering/blocking the pickup. (I just re-read the thread, and Mad Dog already covered this)

Before you buy it, get a PPI done and pay the extra amount for them to put a oil pressure gauge on that engine and check the pressure at different RPM's, etc.

[Mad Dog 20/20]

Adapters are available to allow an oil pressure sensor and oil pressure switch to be connected to where the oil pressure switch normally mounts. So they can be piggy-backed.

That is a typical oil distribution block set-up. I have one on my car. The oil pressure sender and the OE oil pres switch are not "piggy-backed". They are totally independent. If one goes bad it does not affect the other in any way.

7psi?! Im pretty sure it was reading anywhere from 25 - low 30s...

25-30 psi would be extremely high idle psi. 7-15 would be normal

the owner said it was due to it being piggy backed, and drawing off of the original sensor or something..

Sounds like BS.

[libravcs]

A flickering oil pressure light and/or low pressure at idle is not uncommon.

.

This may be true, but doesn't mean it's appropriate and usually indicative of something that needs to be corrected. Accepting an oil pressure warning as being "ok" isnt the best thing to do.

[Mad Dog 20/20]

This may be true, but doesn't mean it's appropriate and usually indicative of something that needs to be corrected. Accepting an oil pressure warning as being "ok" isnt the best thing to do.

Who said it should be accepted as "OK" or "appropriate"?

[CrazyCoder]

I'd walk away from -any- car with a flickering oil pressure light.

Even if the owner says it's the gauge sender, if it was, why hasn't he replaced it? Sure be easier to sell then! And it's not like it's -hard- or particularly -expensive- to do. No, I'd take it as a sign that there is something else wrong.

[savage217]

If the oil viscocity is very thin such as 0-30 then pressure as low as 7 psi and possibly lower can happen. I personally have never had my oil light ever flicker and my warm oil temp psi is never below 8psi. I would be worried about the light coming on. To answer your question more clearly though the normal warm idle psi is as maddog said, 7-15psi normally and when driving about 55-70psi, mine is usually 60 psi at a constant highway speed.

[MIMI1]

in my 99 when i had the S52 in there it read around 10-15 psi at idle after it warmed up and 60 on the highway

on track around 75psi

[(V)3]

my set-up is spa gauge w/ sensor at oil filter housing. running 0w-30. oil pressure is usually around 12psi at idle. never below 10psi even after an HPDE session on a hot day.

when i was i searching for gauges, i wasn't able to find any aftermarket gauge that could be "piggy-backed" off the stock oil press sensor. stock sensor resistance reading are very different than standard aftermarket sensors.

[BMW4LIFE]

This is an interesting thread. When I come off the track I get the low oil pressure light and I run 15w50 Mobil 1. BUT this only started happening after I installed the VDO gauge kit.

Could it be an overly sensitive sensor on the VDO kit?

[Mad Dog 20/20]

This is an interesting thread. When I come off the track I get the low oil pressure light and I run 15w50 Mobil 1. BUT this only started happening after I installed the VDO gauge kit.

Could it be an overly sensitive sensor on the VDO kit?

I dunno . . . if you run over a nail with your right front tire, could it cause the spare in the trunk to go flat?

Aftermarket oil pressure gauges/senders are totally independent of the OE pressure light/switch - they just happen to usually get their data from the same place in the oiling system. But one does not rely on the other for ANYTHING. This redundancy is by design. If one fails, (and aftermarket oil pressure senders fail with some frequency) the other continues to give reliable info. If BOTH are indicating low pressure (OE light is on and aftermarket gauge indicates pressure is below or near 7psi), then you almost DEFINITELY have a pressure problem.

[CrazyCoder]

Aftermarket oil pressure gauges/senders are totally independent of the OE pressure light/switch - they just happen to usually get their data from the same place in the oiling system. But one does not rely on the other for ANYTHING. This redundancy is by design. If one fails, (and aftermarket oil pressure senders fail with some frequency) the other continues to give reliable info. If BOTH are indicating low pressure (OE light is on and aftermarket gauge indicates pressure is below or near 7psi), then you almost DEFINITELY have a pressure problem.

Actually that's not true...

Depending on what he's running, VDO has a dual sending unit that has pressure on one side, and a signal for a light on the other. Part# 360-025, I believe, which turns the light on at 11.4psi. I believe that is what I had in my 323, it came with the oil distribution block I got from leatherz.com.

Still I'd be concerned about the readings, an aftermarket sender is an easy fix. If the owner isn't willing to spend the ~$20 to do it, what else have they also not been willing to spend money on?

[pbonsalb]

Does the Owner's Manual state that the oil light might occasionally flicker at idle without being indicative of trouble? I remember this being the case with a car I owned, but not sure if it is the M3 and my manual is not handy.

[BMW4LIFE]

Actually that's not true...

Depending on what he's running, VDO has a dual sending unit that has pressure on one side, and a signal for a light on the other. Part# 360-025, I believe, which turns the light on at 11.4psi. I believe that is what I had in my 323, it came with the oil distribution block I got from leatherz.com.

Still I'd be concerned about the readings, an aftermarket sender is an easy fix. If the owner isn't willing to spend the ~$20 to do it, what else have they also not been willing to spend money on?

That clears it up. I do have a LeatherZ kit and I just looked up the part # and it does have a 11.4 psi warning and the stock sensor is lower than that. And it is a NEW kit so I am sure it is working fine and I don't think I need to buy another one. I just rev the motor a bit when I see the light to keep pressure up.

I have never seen the oil light in my car before installing this kit and I have tracked it hard for 2+ years.

I believe if it falls below 7psi then I have some serious engine issues, no? But I guess I do not know just how far it falls with analogue gauges.

[Mad Dog 20/20]

Actually that's not true...

Depending on what he's running, VDO has a dual sending unit that has pressure on one side, and a signal for a light on the other. Part# 360-025, I believe, which turns the light on at 11.4psi. I believe that is what I had in my 323, it came with the oil distribution block I got from leatherz.com.

Still I'd be concerned about the readings, an aftermarket sender is an easy fix. If the owner isn't willing to spend the ~$20 to do it, what else have they also not been willing to spend money on?

Actually what I said is still true.

The aftermarket sender you describe operates totally independent of the OE sender. You can install an aftermarket dual sender, but it still does not rely on the OE sender to function, nor does the OE sender rely on the aftermarket sender to function. Aftermarket senders do not "piggyback" off of the OE sender.

The set-up you describe sounds like it eliminates the redundancy of two seperate presssure senders (OE and aftermarket), and instead relies on only the aftermarket sender. This is not ideal. If the sender dies, you have no way of knowing if your motor just lost the pump nut or if the sender died. This results in a code brown tow truck trip home.

With a redundant system, if one sender dies, you can still drive, confident that yoou have pressure.

Does the Owner's Manual state that the oil light might occasionally flicker at idle without being indicative of trouble?

Yes.

[sixx00RR]

i just installed my oil psi gauge and it reads pretty low...the light doesnt come on. and i can tell the gauge is working cause it moves a bit but not even on the highway does it go up....any ideas on the problem?

[Balthazarr]

i just installed my oil psi gauge and it reads pretty low...the light doesnt come on. and i can tell the gauge is working cause it moves a bit but not even on the highway does it go up....any ideas on the problem?

How low is it?

[328iJunkie]

11.4? The light would be on alot... My hot idle pressure is ~8. Crusing 45+. Full load 55+.
And the stock sensor is a switch, I.E. On/Off. There is no way a varying gauge is reading off an open or closed switch. Ever.

Run away. There is prob crap in the oil randomly clogging the pickup while youre driving.
Stock idoit light is set to go off at like 6psi IIRC

[sixx00RR]

How low is it?

bearly noticeable on the gauge...4-5 psi...

light doesnt come one...and my oil level is good.

[bmwpowere36m3]

The spec for oil pressure at idle is 7 psi minimum (warm/hot oil) and a rule of thumb of +10 psi per every 1000 rpm to a maximum of ~59 psi. So if the oil pressure truly is 4-5 psi, then either the oil pressure warning sender is damaged, the oil pressure warning light it burnout/removed or the cluster is damaged.

However more important is if the oil pressure is really that low the oil pump is worn and/or the main bearings.