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    1. Member turbo mike's Avatar
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      09-05-2012 06:46 PM #1
      Fully rebuilt motor, tried two different pumps, still get the same reading. 12psi at idle. I'm used to seeing around 20-25psi on all my other vr motors. What am I missing here? Any suggestions?

      Bentley states I should see over 29psi at 2k which I'm well over that, and up to 101psi at higher rpms. I'm seeing around 75-80psi uptop.

      Just at a loss for ideas.

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    3. Member MRosier's Avatar
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      09-06-2012 11:01 PM #2
      you have nothing to worry about.

    4. Member masterqaz's Avatar
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      09-06-2012 11:22 PM #3
      Oil pressure day or what!

      Nothing at all to worry about. Idle doesnt require much pressure, Ive seen good engines run hot idle pressures as low as 5psi
      diesel life cause cold feet are fun....

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    6. Member turbo mike's Avatar
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      97 Turbo GLX
      09-06-2012 11:38 PM #4
      What are you guys seeing with your setups?

    7. Member MRosier's Avatar
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      09-07-2012 07:01 AM #5
      10 to 15 psi hot idle. 75 on cold start. motor was fully rebuilt about 20k ago and been boosting ever since, driven everyday

    8. Member
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      98 Jetta GLX VR6
      09-08-2012 04:47 AM #6
      not too familiar with the 2.8 engine yet, i just bought my first vr after selling my 2.0.

      but 2.0s have a high and low pressure switch, installing them at opposite locations can cause a fubar.
      dont know if vrs have the same setup but thats something to check.

    9. Member turbo mike's Avatar
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      09-08-2012 01:50 PM #7
      Switches are in the right spot. I'm running a mechanical gauge, meaning an actual line from the top of the filter housing to the gauge in the car. I've tried 2 gauges, autometer and a snap on unit. Both see the same readings.

      I'm going to check a few more things out.

    10. Member JohnStamos's Avatar
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      09-08-2012 11:55 PM #8
      Your idle is perfect, but your building WAY too much pressure with increase in engine speed. Your starving the engine of oil flow already. The LAST thing you want is more pressure at this point.

      If you are hitting 100PSI of pressure, you have an issue with the oil pressure relief valve, or you are overpowering it with something asinine like a 50wt oil.




      What oil are you using, and what are your oil pressures while at operating temp at 1k rpm, 2k rpm, 3krpm, ect?

    11. Member turbo mike's Avatar
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      09-09-2012 12:07 AM #9
      oil is 10-40, at 190* it sees 10psi idle, 2k is shy of 50psi, and max psi is around 75-80. as per the bentley specs, its on point. my issue is, ive been driving vr motors for over 10yrs, none of which ever had this low of oil pressure.

    12. Member JohnStamos's Avatar
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      09-09-2012 12:20 AM #10
      Quote Originally Posted by turbo mike View Post
      oil is 10-40, at 190* it sees 10psi idle, 2k is shy of 50psi, and max psi is around 75-80. as per the bentley specs, its on point. my issue is, ive been driving vr motors for over 10yrs, none of which ever had this low of oil pressure.
      What 10w40? They are not all the same between manufacturers. A few select 10-15w40's are RIGHT off the spec limit of being a 50wt.

      Where does the oil pressure relief valve open for you? You will know based off where readings go stagnant and stabilize. If you are making 50 by 2k and max is 80, you are prob opening the relief valve around 3500rpm, which is starving the engine like crazy at high revs. If this is the case, you should be considering a 30 weight (preferably a low 30. a few select 0w30's would get you there,) and porting the oil pressure relief passage, and not worrying at ALL about more pressure.


      Oil pressure is not a measure of oil flow. Oil flow is 100x more important, especially on engines that are being abused much heavier then stock such as yours.

    13. Member turbo mike's Avatar
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      09-09-2012 06:34 PM #11
      Currently using rotella 10-40. The pressure relief valve is built into the oil pump on the vr6, not sure how I'd port that Max psi at higher rpms should be 101.

      You think that the pump is opening to early? Keep in mind, its two different pumps doing the same exact thing.
      Last edited by turbo mike; 09-09-2012 at 06:37 PM.

    14. Member JohnStamos's Avatar
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      09-09-2012 09:38 PM #12
      Quote Originally Posted by turbo mike View Post
      Currently using rotella 10-40. The pressure relief valve is built into the oil pump on the vr6, not sure how I'd port that Max psi at higher rpms should be 101.

      You think that the pump is opening to early? Keep in mind, its two different pumps doing the same exact thing.
      Not the pump that is the issue, its the ramp rate of pressure increase happening.


      When you hit the pop-off pressure of the relief valve, the pump bypasses oil back to the pan to avoid higher pressure build up. When this happens, oil flow is halted at that rate. So the earlier you hit that pressure point, the LESS oil flow your engine is supplied with. Flow is KEY, not pressure.

      The problem is, flow is MUCH harder to measure then pressure, same reason we use simple Boost gauges to measure inlet pressure to estimate inlet flow rate instead of using a MAF and displaying the exact quantity of air being ingested.

      Same goes for oil pressure as with FI. More pressure isn't always better, it just means more restriction, which equals more work, which equals heat. Just as with FI again, you hit a point of diminishing returns, which on 99% of engines is 10PSI per 1000rpm of oil pressure. Above this is excess and just saps power and reduces engine protection.





      Long way to explain, you have no reason to worry about the pressures you are seeing being too low, infact, you should be trying to get them much lower.

      By 10w40 Rotella, I am assuming you mean Rotella T5. This is a group III base dino oil, and really not a great oil to use in a FI app. It is also very thick for a 40wt. Rotella T6 5w40 would be a much better choice if you insist on a 40wt, but Mobile 0W30 FE (among many other 30wts) would be a much better choice with your oil pressure readings.
      Last edited by JohnStamos; 09-09-2012 at 09:43 PM.

    15. Member turbo mike's Avatar
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      09-15-2012 06:33 PM #13
      Thinking of running Pennzoil 5w30 for break in of the motor, and then swapping it to Mobil1 5w30 afterwards.

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      05-11-2019 11:49 AM #14
      I know this is an old thread but, I am having a similar issue. Prior to the build, I was running 20-25 psi at hot idle. I always ran mobile 1 10w-30.

      Post build, I was using Castrol conventional 10w30 for the break in. Oil pressure barely reads on the gauge. Due to other issues, I installed an oil pressure safety switch that cuts the ignition below 7 psi. Since this is not tripping, I am assuming that I am right around 7 psi.

      I also tried switching to Rotela T4 15w-40 for the break in oil, with no change.

      The only other thing to note is the oil pump was not new with the build. I had replaced it a year before doing the full build so, figured it would be fine.

      Off idle pressures I am seeing...

      RPM psi
      1500 12
      2000 25
      2500 37
      3000 45
      4000 75

      I see the comments saying that down to 5 psi at idle is fine but why would there be such a difference pre and post build?

    17. Member
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      05-18-2019 04:45 PM #15
      No engine gurus that want to chime in? Maybe some pics for attention?

      Anyhow, I couldn't let it go, so...

      I called my machine shop. They thought it was odd. Asked about tolerances. And recommended I put a new oil pump in.

      I ordered an oil pump and figured I should recheck tolerances while I was in there.

      Spec is 0.02-0.06 mm for the mains and 0.01-0.06 mm for rods. I checked everything accept the front main (couldn't get it off without pulling the front cover) and the thrust cap (just did not want to deal with that). Everything was between 0.038 and 0.051 mm per the plastigauge. Or 0.0015 - 0.002 inch. All within spec.

      Now, I have never seen bearings with only a couple of hours run time on them before but, these were sure showing some wear.



      http://photobucket.com/confirmation?...ndc2EnxOAAVEdU

      http://photobucket.com/confirmation?...ndc2EnxOAAVEdU



      And there was a milky substance in the bottom of the oil pan. Not shiny like it was metal.



      http://photobucket.com/confirmation?...ndc2EnxOAAVEdU

      Photobucket is not working?
      Last edited by MOBOZO; 05-18-2019 at 05:07 PM.

    18. Member
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      06-09-2019 12:50 PM #16
      Anyone?

      Just tried another oil pump, same results.

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