Problems with Oil Pressure, need some diagnosis help

[Lopaka]

OK, here is the story, the Oil Pressure light (the one on top of the instrument panel that is red and looks like a can of oil) doesn't come on when the engine is cold, but when it warms up just about 1/2 on temp guage, the light comes on, but when you rev above 1200 rpms the light comes off. (please don't tell me to raise the rpms to 1200 at idle and to make the car colder, I really need some new ideas here)

Here is what I did so far.
1. Changed the sender unit.
2. Checked the sender to make sure it was working.
3. Changed the oil 20/50 weight and filter (two times).
4. Oil pressure test
Nothing wrong
5. I visually inspected the top of the engine oil through the valve covering, and oil is being sent to the top. So the oil pump is working, but I don't know the psi of the oil pump and if it's completley working.
6. Put in 91 octane again, as a friend said poor fuel ignition can cause low pressure. (Not that there was anything but 91 in there, so what the heck I did that too and added gas cleaner why not everything else didn't work)
7. I figure it can't be the bearings because the car pulls strong, and doesn't have any knocking or any sounds that sound bad.
8. I called BMW and talked to a tech, he said that almost never do the bearings or oil pump go (but doesn't mean it can't happen).

So, now, After about 6 hours of checking everything, I still don't know why the f@#$@#-ing light doesn't go out. I am ready to kill a chicken and do some voodoo Sh@#$#@t at this point.

Anyone wanna take a stab at it? Thanks in advance

[Don Stevens]

Ther seems to be something wrong with the pressure switch that controls the light. Maybe master technician Jon Caldito has seen this before and can advise what to do. Otherwise, install an oil pressure gauge, might as well do an oil temp gauge while your at it, and keep your eye on it.

Don

[jsp98m3]

You said you did an oil pressure test in your list. But then you say you don't know the psi. Which is it?

Also you say:

but when you rev above 1200 rpms the light comes on

Did you mean it goes out?

The oil pressure lamp comes on when pressure drops to about 6psi.

The chances of two sending units being bad (you said you changed it) are pretty much nil. But you could try putting your suspect ones in another car.....

Also, it could be a light short on the instrument cluster, causing a parallel (lower) resistance in that circuit. Then the light would come on.

First thing to do is to get a liquid capable pressure gauge screwed into the sending unit location and measure the oil pressure. LIke I said, the light comes on at or below ~6 psi. But the car should idle at about 20psi and raise pretty quickly to 56psi at 3500 rpm or so.

As a test equipment manufacturer I always love it when people's first impulse is to believe the test equipment is screwed up. It is there to tell you something. Look into it the right way. I have news for you, the car wont blow up immediately with partial oil pressure but you are taking chances.

Now tell me this didn't start right after you changed the oil filter...........

[Lopaka]

Originally posted by jsp98m3
You said you did an oil pressure test in your list. But then you say you don't know the psi. Which is it? Also you say: but when you rev above 1200 rpms the light comes on Did you mean it goes out? The oil pressure lamp comes on when pressure drops to about 6psi. Also, it could be a light short on the instrument cluster, causing a parallel (lower) resistance in that circuit. Then the light would come on. First thing to do is to get a liquid capable pressure gauge screwed into the sending unit location and measure the oil pressure. LIke I said, the light comes on at or below ~6 psi. But the car should idle at about 20psi and raise pretty quickly to 56psi at 3500 rpm or so.

Sorry above 1200 rpms, the light goes out. As far as not knowing the psi, I don't how much psi the oil pump is pushing, even though I know it is sending oil up. We did a oil pressure check at 2 shops and it is ok. Now, I did check the sending unit, and I don't have any blame for it.

2 things I am thinking about, tracking down the wires from the oil pressure sender and seeing if it is grounded properly (which I don't think is it or cutting the wire and installing a manual guage).

Now you say that it may "be a light short on the instrument cluster, causing a parallel (lower) resistance in that circuit. Then the light would come on." But would the light stay on all the time?

Also, the light has been on since I bought the car. The guy didn't know what was wrong, so I figured I could fix it since the car drove perfectly and gives no indication as to problems except for the light and I didn't think it was the bearings.

Could it be a fault with the DME? As an example, the check coolant level light doesn't go off either on the check control computer, and I changed that sensor too and have been waiting for it to recycle in the OBD for the past couple of days and about 35 miles of driving (I may need to do more driving not sure). I also redid the thermostat and water pump and did a pressure test on the cooling system the other day So it is baffling. Would the DME be something to look into at this point? Another reason why I am suspecting the DME is that when I bought the car it gave me a 1226 fault (knock sensor). I bought it and just got it in late yesterday, when I did the fault code test again yesterday, it didn't give me the fault code 1226, but gave me the fault code 1222 which is the air/fuel mixture (which could be it if the timing is retarded due to the knock sensor). Go figure.

By the way, thanks for the input.

[jsp98m3]

Usually a bad ground would keep the light from coming on at all. Sounds like something is blocked somewhere if you've tried multiple sensors and 'someone' says the pressure checks ok. The coolant sensor is wierd. You replaced the sensor where? In the overflow bottle or on the side of the radiator?

The air/fuel mixture is possibly a loose or torn intake bellows, the large rubber hose between the air cleaner and the motor.

It sounds like you have lots of little gremlins. It probably wouldn't hurt to take it in and get the car gone through.

[Kevlar]

Originally posted by jsp98m3
But the car should idle at about 20psi and raise pretty quickly to 56psi at 3500 rpm or so.

When my car is idling, oil pressure is about 8-9psi.

[jsp98m3]

You're running the viscosity equivalent of water, remember?

[Kevlar]

You may be right...

I'm trying to think if I converted to 0W-30 before or after I did my oil pressure guage install. The timeline of my mods tends to all run together now.

But here's a question... if my car was recommended 5W-30... shouldn't it have the same oil pressure with me running 0W-30 in it (when warm of course)?

[Lopaka]

Originally posted by jsp98m3
Usually a bad ground would keep the light from coming on at all. Sounds like something is blocked somewhere if you've tried multiple sensors and 'someone' says the pressure checks ok. The coolant sensor is wierd. You replaced the sensor where? In the overflow bottle or on the side of the radiator?

The air/fuel mixture is possibly a loose or torn intake bellows, the large rubber hose between the air cleaner and the motor.

It sounds like you have lots of little gremlins. It probably wouldn't hurt to take it in and get the car gone through.

I replaced the overflow sensor. I checked the fan sensor (side of radiator) and made sure it works.
AS far as something being "blocked", are you thinking maybe the bypass oil hose (I can't remember the name, but it's the one when the car shuts down and let's oil drain???) or something else inside of the motor?

I'm going to replace the knock sensor today, and will take off the intake manifold and see under there. Yeah, gremlins is right. It's taking me a week longer to fix than I anticipated, and luckily I have the time and extra transportation to let the car sit and work on it at my leisure. I'll check the sender wires again for any grounding problems. But you don't think it's the DME, huh?

[gschomi]

Originally posted by Kevlar


When my car is idling, oil pressure is about 8-9psi.

Im at about 10-12 PSI when im warmed up at idle with the EMW guage kit. I use 0w30 or 5w30 mobil one. Anything under 20PSI seems low to me at idle but i guess this is normal or so my BMW tech says.

[jsp98m3]

Beats me. I'm not discussing oil anymore. ~20 is what mine and a few others read. You run a different brand of oil and maybe a different year car. So it's not apples to apples.

[Kevlar]

Originally posted by jsp98m3
Beats me. I'm not discussing oil anymore. ~20 is what mine and a few others read. You run a different brand of oil and maybe a different year car. So it's not apples to apples.

Understandable... the oil debate has gone on long enough, to each and everyone their own.

Back to the original problem... maybe there is something wrong with the belt that spins the oil pump or the oil pump itself? Maybe it's not providing the necessary spin to turn it fast enough at idle.

[Bob ///M3]

Kevlar,

My M3 has about 11 to 12 psi of oil pressure at idle when the oil temperature is around 212 degrees F. This is normal. Maximum oil pressure is about 58 psi. I don't know why you're oil pressure reading seems to be two or three psi lower than everyone else's. You would find the exact same pressure readings if you used the BMW 5W-30 oil. It may be the sensor that could be off slightly. Do you get a reading of about 58 psi at full throttle? If it is a little less it could very well be the sensor.

By the way, a 30 weight oil is a 30 weight oil! You could be using 0W-30, 5W-30, 10W-30, 15W-30 or straight a 30 weight oil of either petroleum base or synthetic and at 212 degrees F (100 degrees C) any one of these oils will be weighted the same...

Jim's comment about 0W-30 being like water is unfounded because any multi-viscosity oil is at its "thinest" when the oil is at 212 degrees F... We know it is a 30 weight oil, right? A 0W-30 oil is "thicker" at room temperature than is a hot 50 weight oil for example! But of course the 0W-30 would be thinner than a 20W-50 if both were measured at room temperature which is far below the normal operating temperature of 212 degrees F. You actually want your oil to be as light as possible when you crank up the engine to reduce wear. It's a shame we can't get our hands on an oil that is as light as "hot" oil! But that's the advantage of using a 0W oil because it's as light as the oil makers are making it and it protects better than a 5W, 10W, 15W and especially a 20W oil when you first crank up the engine...even on a real hot day..........plus it meets the recommendations of BMW which is a 30 weight oil.

In just so happens I changed my oil and filter today! Any quesses on what I used?

Bob ///M3

Originally posted by Kevlar
You may be right...

I'm trying to think if I converted to 0W-30 before or after I did my oil pressure guage install. The timeline of my mods tends to all run together now.

But here's a question... if my car was recommended 5W-30... shouldn't it have the same oil pressure with me running 0W-30 in it (when warm of course)?

[Bob ///M3]

Lopaka,

I agree with Jim, it does sound like you have possibly a number of things that should be checked out by BMW. They can hook their fancy computer gizmo up to it and check everything very thorughly. I would suggest you take it in too.

Good luck!

Bob ///M3

Originally posted by jsp98m3
It sounds like you have lots of little gremlins. It probably wouldn't hurt to take it in and get the car gone through.

[jsp98m3]

Bob,

You can use whatever you want. But you really do need to stop making a point of touting startup wear characteristics.

Assuming that the motor has been run in the last couple of weeks there is a film coating all parts. The oil pump will pump almost any oil that is the correct viscosity throughout the engine at almost the same speed.

I'll allow that the thinnest oils might get to the parts a fraction of a second sooner. But at only 700 rpm, it's an irrelevant timing issue.

If these vaunted oils have to be thin to get pressure to the parts that soon, maybe they aren't good oils to begin with? We know that is just not true, they leave behind a film with additives that do an excellent job. So startup wear just isn't an issue. If it was, there wouldn't be any motors running organic oils left on the planet over 5 years old. They would have all seized up.

Lighter weight oils do a good job in cool to cold weather and in engines, like the BMW, that have the close parts tolerances to utilize them. Argue the points that are supportable.

[Kevlar]

Hey... we've heard both sides of the great oil debate in a different thread... and I thought you guys agreed to disagree. Jim can continue to pass along his knowledge about the 15W-40 and Bob can continue to pass along his knowledge about the 0W-30. No reason to continue arguing about it. You've both presented good sides... now it's up to people to decide for themselves.

Anyway...

My M3 has about 11 to 12 psi of oil pressure at idle when the oil temperature is around 212 degrees F. This is normal. Maximum oil pressure is about 58 psi. I don't know why you're oil pressure reading seems to be two or three psi lower than everyone else's. You would find the exact same pressure readings if you used the BMW 5W-30 oil. It may be the sensor that could be off slightly. Do you get a reading of about 58 psi at full throttle? If it is a little less it could very well be the sensor.

At full throttle... I get around 57-59 psi. I'm guessing that since 58 is maximum pressure, that I am right on the money.

At startup, the PSI is around 30-40psi until I start to drive, then it'll stay up at 40psi during idle. Then as the car warms up, the PSI slowly starts to come down. Initially It'll be around 40psi at idle, then 30psi at idle, then 20psi at idle, then 11psi. The lowest I've seen it at idle is about 8-9psi. I did see 7-8 psi after a extended trips at triple digit speeds.

[Bob ///M3]

Kev,

It sounds like you are getting very standard readings at all times with possibly the exception of when the oil is at normal operating temperatures where the pressure is down two or three psi. I don't think it's anything to be concerned about at all however.

Bob ///M3

[Lopaka]

Originally posted by Bob ///M3
I agree with Jim, it does sound like you have possibly a number of things that should be checked out by BMW. They can hook their fancy computer gizmo up to it and check everything very thorughly. I would suggest you take it in too.

Thanks everyone for their input. I actually have been having thoughts of taking it it. At least for them to diagnose, and for me then to do the grunt work hehehe. If I'm gonna get raped by the stealer, it won't be for full admission.

By the way, didn't want to start an argument about oil, just wanted some friendly advice. We're all friends right? Ok, shake hands

Thanks everyone

[jsp98m3]

I'm sorry. I'm never in a good mood when the Nasdaq shuts down, extends their hours and my brokerage doesn't let me know.

I picked a great stock yesterday and made $85K on one stock alone. I missed the sell bump at $2.50 profit per share and took $2 thinking the market was closing. I could have made $141K instead. This company was doing a secondary public offering, it was the last day of the quarter and the company was joining the Russle 1000 which meant that brokers had to add it to their portfolios if they didn't have it already. 3 million shares changed hands in the last 15 minutes.

So I'm just an ill tempered son of a bitch with the equivalent of a corn cob ass today. Bastard broker. It seems the more money I accumulate, the more I worry about it.

On other business.....

You said you were going to pull the intake. That is a bear of a job. Have you done it before? There are lots of connections under there that have to be done pretty much by feel and your forearms can't be thick. Not that it can't be done. I've had mine off a few times. If you decide to go ahead with it, I suggest you consider putting the car up on jackstands. I'm 5'9" and the job is the most comfortable for me with the car 7" up in the air. Its a bitch to do all hunched over. I have a lift in my garage so I can get it right where I want it. Just a thought.

[Kevlar]

I picked a great stock yesterday and made $85K on one stock alone. I missed the sell bump at $2.50 profit per share and took $2 thinking the market was closing. I could have made $141K instead.

I think I'm in the wrong business...

[gschomi]

Originally posted by Kevlar


I think I'm in the wrong business...

No kidding. I bust my but azz a jet mech. and im lucky to get 40K a year. LOL

Hey Jim, how about posting some great penny stock buys for us? I bought WDC at 3 1/4 over a year ago and its still around 3 1/4.

[jsp98m3]

Buy what you know. Talk to your suppliers and customers. The ONLY people who make money in the market are people with inside information or people who can sit in the market long term without touching the money. I do both. Discounting insider info, on average the stock market makes BIG money, as a percentage, about 10-12 days per year. Nobody can successfully guess those days even 1/4 of the time. So you can't get in and out. You have to be in all the time. Then you make a little or lose a little all year, generally rising at roughly the same rate as Fed Reserve returns. But 10-12 times a year you really make a haul.

I've been making on average 800-1000 a day for quite a while. Of course I have a lot of money tied up. Yesterday was one of those whales you wait for. So I'm severely pissed I missed out on a third of it. I could have churned the money two more times if I had known. It's like the grocery store. They don't get rich because they sell a can of beans for 50 cents and make a penny. It's because they sell that can of beans 200 times....

Yesterday near the close the stock I was trading was popping up and down $1.50 at a time. The company would release big blocks and the houses would grab it. In between the price would drop as little chunks of 500-5000 shares would come on-line from individual investors that were below the radar of the houses. I bought those a couple of times. Churning the roll. I could have kept it up another half an hour! Bastards. But I guess I can't blame them. I'm small potatoes and I had $800K active.

And if you think I'm going to give stock tips, you'll believe I'm going to fly out and do Bob's oil changes

[BMWguy206]

BMW Specs on oil pressure according to Technical Information under Technical Data.

Oil Pressure at idle speed with engine at operating temperature MINIMUM BAR - 0.5 (7.35psi)

Regulated pressure is 4.0 BAR (58.8psi)


The DME isnt the blame since it does not get any input signal from a low or zero oil pressure from the switch. The OBC and the Check Control Module also does not monitor oil pressure. The only control unit that monitors it is the Instrument Cluster via the pressure sensor switch.

I have no idea what can be causing the complaint you're experiencing with the low oil pressure light lighting up on you. I'm not sure but upon installing a new pressure sensor, arent they supposed to be primed?

I wish I can help but you're better off taking it to a BMW dealer or an independant shop.

Oh and there's a misunderstanding.. I'm not a Master Technician. At least that wont happen in about 2yrs.

[Bob ///M3]

Jim,

Are you seeing ~20 psi oil pressure at idle for your M3 when the oil is at normal operating temperature of about 212 degrees F?

Bob ///M3

Originally posted by jsp98m3
~20 is what mine and a few others read. You run a different brand of oil and maybe a different year car. So it's not apples to apples.

[jsp98m3]

40 cold idle, 20 warm idle (220-225), ~56 indicated at speed.

It currently has 7 quarts of Redline 20W-50 in it. Ambient temperature is 77 degrees.