Arrgghh! Flickerig Oil Light

[Curt C]

Well crud. My daily driven 1999 S52 with 135,000 miles on the odometer now has the flickering oil light at idle. Yesterday was a mid 90’s day in Las Vegas. Lots of stop and go on the freeway going up the hill. It did this several months ago too when it got hot. I have noticed that the average oil temperature has increased over the last two summers. The temperature gauge used to stay right in the center at 230. It now runs 240 - 250ish on hot days around town. Last summer I saw close to 260 on a 115 degree day traveling at 80 MPH from Los Angeles to Las Vegas. I was not too worried because that was going up the Halloran pass which is a long, long steep grade.

I have a VDO oil pressure gauge. It typically shows 10 psi higher than RPM under load eg. 2500 rpm = 35 psi. It does show quite low at idle (around 5) but it’s an electric gauge. I am running Mobil 1 10-40. Last oil analysis was done at 125,000 miles and was clear. I have done extensive searches here. I don’t think a loose oil pump nut would cause this? The gear is either on or off right? With hope I have a broken or clogged pickup and or failing oil pump? I am going to change the oil pressure sending unit today for shifts and giggles but I am not too encouraged that this will fix the problem.

I would like to hear your thoughts on what is possibly going on here. The temperatures in themselves do not concern me but the increasing trend along with the now flickering pressure light is disconcerting. For what its worth, I have owned this car since 40,000 miles and it has been well maintained with no tracking. Its stock except for the Dinan ECM flash that it came with. Next step is to pull the pan and inspect the pump and bearings right? Its too soon for this!?!?

[rdsledge]

A clogged pick up screen,well cause the oil pump to burn up giving you the symptoms you describe.

If the oil has been changed on a regular basis I would doubt it would be a clogged up screen.The screen would be clogged with sludge,

Would start by checking the gauge.

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[328 Power 04]

Welcome to my world. Pretty much exact situation, even the oil temps and all. I have been battling this on my 99 S52, for quite a while. Conclusion comes at the end.

What I have done, in rough order:
-Changed oil pressure switch
-Added VDO pressure gauge. 6-7 psi on very hot idle. Over 10psi per 1000rpm, until the 57psi (or whichever it is) relief valve opens, then remains at that.
-Dropped oil pan, rebuilt oil pump with new internals, new spring and valve.
-Safety wired the Oil Pump Nut. It was not loose.
-Secured the oil pickup.
-While I was there, I checked the conrod bearings. They were perfect.
-I replaced the conrod bearings, and new BMW OE conrod bolts.
-Rebuilt VANOS seals.
-I put in Royal Purple 5w40 inside = the thickest 5w40 you can buy.

So far, nothing changed. Still the same.

So frustrated, I bought a spare low mileage S52, waiting for my S52 to bust... It has not. Both Randys have heard my complaining and idea bouncing, about how frustrated I was. Especially after putting SO MUCH work into it. So I still have a very good S52 waiting.




On to cooling system. I have a fan delete (not a great idea), new stock temp thermostat, aluminum housing, lowered 80/88 radiator temp switch. Radiator is still stock from PO. Must change it, I believe it is restricting flow.
-Bled and rebled, searching for an air pocket. After bleeding, I no longer see 260 deg F oil temps. Max 240 now.

I noticed that when oil pressure light flickers on hot idle... if I go outside and spray the radiator with hose water, the oil pressure light goes away within seconds.
Points to a cooling issue.

I will be replacing the radiator, and installing S54 oil filter housing with aftermarket oil cooler.



Other points to consider:
-The manual clearly says that oil flickering on hot idle is normal. (!!?)
-I was told by an older BMW master tech that there was a TSB back in the day for certain S52s that had an issue with the oil pressure check valve in the head. It's cheap, but a lot of labor to replace.




Conclusion.
Go to 15w50, or 10w60 (my next plan, I was given some 18 liters of it for favors), add an oil cooler, make sure your cooling system is up to par.

If you ever have your head off, replace that check valve. There is no problem if you keep on driving it (as long as your oil system is good).
Good luck!

[Curt C]

Hello 328 Power 04. I have seen some of your posts in my searches. Thanks for chiming in. It is frustrating. Interesting - I too have the fan delete but I have installed a Spal puller. I replaced the radiator (stock) and pump (steel impeller) at 120,000. Stock T stat and fan temp sender are still in place. I will start to monitor coolant temperature too. Perhaps it is just an age thing of sorts? If your con rod and main bearings looked good I would not be to concerned. These things do idle at a ridiculously low level - 500 rpm in my case. I think I am going to replace the oil this weekend with 15/50 and send off another sample to Blackstone. Assuming the sample is good then my dilemma is whether to pull the pan and inspect the bearings and pump now or wait and see if things get worse. As I noted above the pressure is good when driving and the temps are really not that bad especially considering where I live.

[328 Power 04]

If you had starvation, your hydraulic lifters would really be singing their song. You would know.
I had thought I had loose bearings, and that just wasn't the case. All that is left for me is a different oil filter housing (S54), and maybe one day the check valve, part number 11121735180.


What is your actual idle rpm? Not going by the tacho. The 'halfway' line between 0 and 1 is about 650rpm actually.

I also bumped my idle from the stock 700 to about 780-800 using software edits to keep me from seeing that light.

[rdsledge]

The heavier oil will probably make the light go out. I run 20/w50. I thought oil pressure at idle was supposed to be 5 psi.(heaver oil makes the oil pressure higher)

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[328 Power 04]

If I remember correctly the pressure warning switch is 0.5 bar, which is ~7psi.

[gmushial]

Not to hijack the thread... but if one wanted to add an actual oil pressure gauge: one would obviously need a gauge, a sender and a switched 12v to power the gauge... but what about a place to put the sender? The standard VDO pressure sender + underpressure switches, are quite a bit larger than a simple underpressure switch - is there room to replace one with the other? Or does one need some type of adapter/spacer to have room... I'm talking in the context of a M52TUB25. [having 200k mi on the motor, it's getting that time to keep an eye on pressure, ie, suspect bearings are starting to get thin... and search for oil pressure gauge doesn't come up with any obvious threads/answers.]

[Curt C]

OK. I changed the oil to Mobil 1 20W-50 and replaced the OEM pressure sender. Went for another drive. it is 91 today. Coolant was steady between 199-205 per my little OBDII App. Idle is 675 ish. Doing 80 mph up the hill puts oil temp just right of center - maybe 240 at most. No lamp. The heavier oil should and appears to have helped. Now we wait. We wait for the lab to come back on the oil and we wait for the temperature to get over 100 for some real testing.

Gmushial. The are some adapters out there that go between the oem sender and the port. Check Leather Z. I think they carry them.

[Curt C]

Update:

Well when the temperature hit mid 90's again the light flickered even with the 20-50 oil. The clutch and 3rd gear synchro have been needing attention so I took the car to the shop. Mechanic says the connecting rods look perfect. He did say the oil pump had a broken / cracked bracket which could be causing some vibration. The pickup looks okay. I had him save the pump so I can document later. Blackstone oil analysis came back fine too. The lab did note that as cooling systems age they are not as effective and that one has to choose between heat and pressure. It will be interesting to see if the new oil pump solves the problem. If it does not I am not going to worry too much about it. I will kick the idle up a little to keep the pressure above the switch level and watch the pressure at higher RPM via the VDO electric gauge. Question - is there a bypass mechanism in the filter housing that could be causing the pressure to the switch to go below minimum at idle? Thanks

[Muzz258]

Do some research on the two small o rings on the bottom of the plastic filter top/insert in your oil filter. By memory they are instrumental in stopping oil bypass, but I can't remember exactly what gets bypassed and could not find the tread that explains it. When you change the oil filter and lift the the filter top, the o rings break their seal and allow the oil to drain to the crank case. Maybe they are leaking a little and letting your oil bypass when the car is running?

[Curt C]

Well Damn. The new oil pump did not fix the problem. The light still flickers at idle when the ambient temperature exceeds 90. I at least have the peace of mind that the pump is new, nut is on, the connecting rod bearings look good and the oil analysis results have been good.

In the M3 forum I found this post: http://www.bimmerforums.com/forum/sh...sure+oil+light

He solved his flicker problem by changing the oil filter housing. He states:

“If your pressure is reading low on the gauge, consider addressing the oil filter housing next. There is a pressure relief valve built into the housing that, theoretically, can get stuck and affect the oil pressure in the filter housing itself. This is the limitation of reading the oil pressure on the back of the housing because what you're reading is the pressure at the housing not necessarily the pressure in the engine. I don't know if the housing can be cleaned, repaired, rebuilt, etc. In my case I chose to put on a whole new housing ($355 for the parts and it came with a new gasket and oil filter from BMW).”

Is there a pressure relief valve on our filter housing? Edit: I just saw the post above from Muzz. Perhaps the o rings he speaks of have been compromised? I don't see an O ring part on Real OEM in the diagrams. Or are you speaking of the O rings that come with the filter? Those are changed regularly in my case.

In the meantime I will raise the idle at maybe switch to the 10-60.

[Muzz258]

Just realised that the oil filter system on a Z3M is different to the non-M Z3. My comment about the O-rings does not apply to the M Z3's

Sorry for any confusion.

[Curt C]

For those following - It appears that faulty oil squirters can cause a low pressure situation at idle. http://www.bimmerforums.com/forum/sh...e-at-Idle-Info

[Curt C]

I hate it when folk don't follow up on their threads so I feel compelled to do so. Update:

I sourced a little 11.25 x 4.8 inch Setrab oil cooler and hooked it up to an oil filter lid sold by Bimmerworld. That little unit knocked the temps down 20-30 degrees. I beat the piss out of the car on a 104 degree day. While the oil did get up to 240 degrees per the stock gauge the oil pressure stayed at around 10 psi and no oil warning light. Cruising oil temp is 200 - 210. In winter I plan to block the cooler with black aluminum tape. So - I will continue to drive and test the oil at regular intervals. With hope I just have some broken oil squirters. I want to thank 328 Power 04. He was gracious enough to offer to reprogram my computer and raise the idle in an effort to keep the oil pressure above the trigger. I did not do this but his offer is commended.

[328 Power 04]

Glad to be available to help.

I am also happy that you followed up, because my oil cooler is *still* not installed but am looking forward to results like yours.

[jclausen]

We had a tech once put the oil filter stand in the cleaning machine because he was replacing the oil filter stand upon Assy the oil light started to flicker at idle, we tried various things then we in stalled the new oil filter stand and the oil light stayed off. Maybe one of the valves in the oil filter stand are acting up. And we only clean these by hand now

[Geo31]

Curt, I'm curious if the solution you mention has held up.

I'm also in this club. I just brought my Roadie back to life after a 4 year sleep. It has some issues I need to address, but none of them appear to be serious enough to seek immediate "medical attention." I'd forgotten about this issue, which reared its ugly head a few months before I stored her (well, detailed her an threw a cover over her).

Since the car is not at idle a whole lot, I'm not freaking out about it, but it's one more thing on my To-Do list, and with another older Bimmer, you know the list is long.

Whatever the issue is, German engineering being what IT is, the solution for one is likely the solution for almost all.

[Geo31]

Bump.....

Can anybody confirm this is a long-term fix?

[328 Power 04]

I am starting to believe jclausen, as I have changed so much on mine, except the oil filter housing, and still have the idle pressure issue.

BTW, I am in Conroe, that's quite close.

[Geo31]

I am starting to believe jclausen, as I have changed so much on mine, except the oil filter housing, and still have the idle pressure issue.

BTW, I am in Conroe, that's quite close.

I guess that's another thing I need to put on my "wish" list at ECS. I'll get to it eventually. From reading through this, I'm not inclined to get overly worried. If you think about it, unless you're driving in steady stop and go traffic (like I did on the way home last night with my Roadie), it's probably at idle for only 30-60 seconds at a time anyway. A bigger issue for me right now is the clutch is not fully disengaging sometimes. I need to bleed the hydraulics and change the hose to braided. Another to-do. Heh.

Yeah! You're right down the road. Which side of 45? I'm just north of Willis near Calvary Rd (Emerald Lakes).

[Curt C]

Hello Geo. Yes the cooler worked. No flicker this summer. I am convinced my problem is some piston squirters that do not close at idle like they should and thus bleed some of the pressure off.

[Geo31]

Thanks Curt. I need to change the oil in my Roadie. I think I'll throw some Marvel Mystery Oil in the crankcase for a tankfull of gas. If something is sticking, that may loosen it up. After that, I've got some work to do.

[Curt C]

Hi Geo. The squirter fails because of a loose or broken spring. Mystery oil won’t help that if that is your problem. What viscosity oil are you running?

[Geo31]

Hi Geo. The squirter fails because of a loose or broken spring. Mystery oil won’t help that if that is your problem. What viscosity oil are you running?

Ah, that makes sense.

I don’t remember what is in tha crankcase, but probably whatever the factory recommends. It’s been 4 years [cue embarrassment]. I just revived it. Gotta change it soon.

Recommendations?