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  • Oil pressure light coming on at idle - is this a major cause for concern

    I just swapped an s-14 into my 1991 318is. After getting it up in running everything appeared to be fine aside from some minor issues. One of which is the M cluster I installed must need new SI board batteries or a board since the tach is twitchy / intermittent. I took the car to the track and ran it for a few sessions as a shake down and all was well, it ran great. After sitting for a few weeks I used the car again today and now the oil pressure warning light is coming on at idle. As soon as the rpm climbs past 1200 or so it goes out. Oil level is fine. It didn't do this at all during the track day... Also the motor has about 5k miles on it since it was refreshed by the PO at a shop that I know and I'm assuming the oil pump was check or replaced. I did not do so prior to installing the motor in the car I did however add both a horizontal as well as vertical baffles. Can this be the symptom of a bad sender or perhaps my SI board or should I be looking for a more serious issue. Any suggestions on the best approach to determine the cause would be appreciated.

  • #2
    The light comes on at a dangerously low level, something like 8 psi or so iirc. I have my alarm trip point at 30#

    I would get a sensor and measure the actual pressure in there, to be certain.

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    • #3
      Remove sensor and measure oil pressure with a 0-100 psi gauge and report back what you find.
      Ron ///Man

      • '91 Gr-A Former CiBiEmme / Ravaglia - Sold
      • '90 M3 Faux EVOII Alpineweiss 36K Orig Owner - The Queen
      • '91 M3 Faux EVO III Brilliantrot Euro Driveline - The Rocket
      • '91 M3 Faux Gr-A Club Racer DM - The Alter EGO
      • '89 M3 M3T / ITR Club Racer
      • '94 Spec E36 - Eh....
      • '09 M3 - Tarmac Terrorist
      • '04 330Xi Sport 6 Speed - Snowmobile
      • '07 530 Xi - Highway Star
      • http://www.imwcarparts.com/e30-m3-parts.htm


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      • #4
        Try replacing the sensor first. It costs only a few bucks.

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        • #5
          Originally posted by Ron ///Man View Post
          Remove sensor and measure oil pressure with a 0-100 psi gauge and report back what you find.
          Thanks Ron,
          I will get some readings over the weekend.
          Hope it's not the pump going bad which I suspect it is - they are BO with BMW until Oct. this year.

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          • #6
            Markus is selling some awesome BNIB EVOIII pumps if push comes to shove
            --------------------------------------
            The God's chariot... (OO==[][]==OO)
            sigpic

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            • #7
              Originally posted by Ron ///Man View Post
              Remove sensor and measure oil pressure with a 0-100 psi gauge and report back what you find.
              Readings I got

              Oil Cold

              RPM PSI

              800 - 15

              2k - 35

              4.5K - 60

              6k+ - 65

              Oil Hot

              800 - Negligible

              2k - 10

              3k - 22

              4.5 - 36

              5k - 40

              6k+ -48
              DOES THIS INDICATE A BAD PUMP OR SHOULD I BE COLOOOKING AT BEARINGS ???
              Last edited by danse30m3; 07-20-2013, 07:24 AM.

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              • #8
                Curious what oil are your running. 10PSI would concern me but I am not an expert.

                Cheers,

                Jim
                Livin the Dream

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                • #9
                  Those numbers are too low. Don't drive the car anymore. You said someone just rebuilt the engine, I would find out exactly what was done. Show them the readings and see what they offer to do for you. Typical hot readings are 30-72PSI. You shouldn't really be under 30PSI much if at all. I hope it's as simple as an oil pump but I somehow doubt it. You said it was fine when you tracked it, then the next time you drove the car it started exhibiting low oil pressure. That's not good.

                  88 M3 - LACHSSILBER/M TECH
                  89 M3 - ALPINEWEISS II/SCHWARZ
                  85 323I S52 - ALPINEWEISS/SCHWARZ
                  91 M TECHNIC TURBO - MACAOBLAU/M TECH


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                  • #10
                    Originally posted by danse30m3 View Post
                    Readings I got

                    Oil Cold

                    RPM PSI

                    800 - 15

                    2k - 35

                    4.5K - 60

                    6k+ - 65

                    Oil Hot

                    800 - Negligible

                    2k - 10

                    3k - 22

                    4.5 - 36

                    5k - 40

                    6k+ -48
                    DOES THIS INDICATE A BAD PUMP OR SHOULD I BE COLOOOKING AT BEARINGS ???
                    Originally posted by Reelizmpro View Post
                    Those numbers are too low. Don't drive the car anymore. You said someone just rebuilt the engine, I would find out exactly what was done. Show them the readings and see what they offer to do for you. Typical hot readings are 30-72PSI. You shouldn't really be under 30PSI much if at all. I hope it's as simple as an oil pump but I somehow doubt it. You said it was fine when you tracked it, then the next time you drove the car it started exhibiting low oil pressure. That's not good.
                    Way low. My car, running 15/50 mobile one is around 80 psi on cold start idle,at a 50* ambient temp, and around 90psi above 6k warm. Idle warm is around 40 psi.

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                    • #11
                      Check the oil pump relief port. I would expect to see those numbers if it was wide open.

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                      • #12
                        Hi,
                        The word "Track day" in your first post has set off alarm bells for me and reminds me of my track day all was well until the next day when the engine sounded rougher and oil pressure was lower than previous day. I learned the hard way race built S14 engine was not suitable for track day with out extra sump baffles and 1l extra oil, one crankshaft later.

                        I see you have horizontal and vertical baffles which is ideal, by any chance did you add extra oil for the track day and has the low oil pressure shown up straight after like the two are connected or do you suspect the they are not connected.

                        Next step will most likely be removing the sump for inspection of the main and big end bearing shells, plasti gauge clearances if the shells look visually okay. Depending on how that goes if all is good as others indicated the oil pump next for close inspection.
                        Dave.

                        E30 M3 1987
                        Mini Clubman GT
                        BMW E36 323 Msport
                        Toyota Corona
                        KTM 200EXC
                        Honda CB50 (1979)

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                        • #13
                          Originally posted by Todd black 88 View Post
                          Check the oil pump relief port. I would expect to see those numbers if it was wide open.
                          I'm new to the s-14, does this require removal of the oil pump?

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                          • #14
                            Originally posted by Dave @nz View Post
                            Hi,
                            The word "Track day" in your first post has set off alarm bells for me and reminds me of my track day all was well until the next day when the engine sounded rougher and oil pressure was lower than previous day. I learned the hard way race built S14 engine was not suitable for track day with out extra sump baffles and 1l extra oil, one crankshaft later.

                            I see you have horizontal and vertical baffles which is ideal, by any chance did you add extra oil for the track day and has the low oil pressure shown up straight after like the two are connected or do you suspect the they are not connected.

                            Next step will most likely be removing the sump for inspection of the main and big end bearing shells, plasti gauge clearances if the shells look visually okay. Depending on how that goes if all is good as others indicated the oil pump next for close inspection.
                            Dave.
                            ,

                            sounds ominously the same, oil was full plus some for the track day, and all was fine, I didn't use it after for a weeks then drove it for a short trip when I noticed the light coming on. it could be running slightly rougher but I'm not certain,... Would changing the pump and repeating the test make any sense, putting a new pump on wouldn't be a bad idea in any event ???
                            Last edited by danse30m3; 07-20-2013, 02:14 PM.

                            Comment


                            • #15
                              Hi
                              To remove the oil pump requires removing the lower sump, to check the bearings requires upper and lower sump removing.
                              Remove the lower sump look for quite a lot of flaking brass material in the bottom of the sump this will tell if the bearings are damaged.

                              Oil pump things to look out for would be the sprocket nut loose or the splines stripped in the sprocket this has happened before to a forum member, then the oil relief valves check for debris/sticking there are two on the pump and both have strong springs. Just to clarify with mine the engine still ran good but sounded rough/rumbly.

                              Bolting in a new pump and test again, I am not sure on this one and suspect unless you can find something wrong with the pump it will not fix the problem.
                              Dave.

                              E30 M3 1987
                              Mini Clubman GT
                              BMW E36 323 Msport
                              Toyota Corona
                              KTM 200EXC
                              Honda CB50 (1979)

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