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Thread: Cranking to get oil pressure

  1. #1
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    Cranking to get oil pressure

    Getting ready to do 1st start on 818 with 2002 WRX donor obtained from one of of our vendors. Redid water pumps , belt, but left oil pump alone.

    Can't get it to show any pressure on oil pressure gauge with sender in sandwitch adapter mounted to oem oil cooler. Tried several times cranking as long as 30 secs.
    Plugs out so cranks fast. OP gauge works. New STI oil pan and pickup. One would think of missing o ring in pan but I believe I did that correct.

    Any one else have long cranking times to get oil pressure. I know g-rotor pumps can be fussy. Ideas??

    Thanks

  2. #2
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    how long total have you cranked it? a few minutes? Make sure oil level is good. I'm pretty sure you need a different oil dipstick when you add the STi pan and pickup to a 2.0L.

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  4. #3
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    I had to take the oil pump off and prime it, builders say it doesn't happen often ,but
    when it does.....worked for me.

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  6. #4
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    Quote Originally Posted by Jim Haar View Post
    I had to take the oil pump off and prime it, builders say it doesn't happen often ,but
    when it does.....worked for me.
    Did you use light grease or STP oil to prime??

  7. #5
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    Don't remember , seems like anything heavier than regular motor oil would work.
    Good luck !

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  9. #6
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    I had a very similar problem, I even used heavy weight motor oil. I ended up continually cranking the motor with a battery booster to get higher RPM's out of it. After quite a while I did get oil pressure.

    Is the motor freshly rebuilt? If so the assembly lube should protect it but if not then I guess there is a risk of damage after prolonged cranking but who knows how much that would take

  10. #7
    Senior Member STiPWRD's Avatar
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    Try removing your oil filter and cranking it - this is the first place where oil will be pushed into. If oil starts to flow, put the filter back on and crank again to see if you get pressure. If still nothing, you may have a bad oil pressure sensor. Typically, these are resistive sensors so you could also try checking it with a multimeter.

  11. #8
    Senior Member SixStar's Avatar
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    All good information here. We sell about 300 engines a month and this happens 1:200 times I would say.

    The three proven methods are:
    Pack the oil pump with assembly grease, we use Driven
    Pre-lube the engine using a melling pot
    Release pressure/bleed the system by removing a plug, line, sensor, filter, etc.
    Owner/builder - AEM Intakes 818R #85

  12. #9
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    Thanks for all the replies. Good info which helped fix it.
    Being new to Subaru and not knowing till after the problem that the pump is grotor, I took pump off donor but did not
    know to pack rotor area with assembly or other heavy
    oil. Thus I caused my own problem. The 1st thing I tried worked. I took a spare BIG battery, make 3 ft new 1/0 ,*cables direct to starter, preserved the car battery to suppy crank volt and pwr to all else like dash and op gauge. Then
    cranked it over, got much faster crank speed of op and after 30 sec light went out and had about 80 psi on gauge.
    Also had charger on external battery to maintain as much
    voltage as possible.
    Thanks for help. Group is priceless for builders
    frank

  13. #10
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    Glad you got it going!

    For future reference you can pre-lube the engine with a cheap DIY setup. A Home Depot sprayer, some tubing, and a 1/4" barb into 1/8" BSPT fitting. The fitting is the hardest part to source, so I sell them, I think I have one or two left.

    NOTE: Even doing this still requires several seconds of cranking to get the oil pressure up.

    -OR-

    Replace the oem Subaru block 1/8" BSPT fitting fitting with one that has an 1/8" NPT port. That way you can use a common 1/8" NPT to 1/4" barbed hose fitting available at HD/Lowes. And the best part is you can now put a oil pressure sensor or oil temp sensor with 1/8" NPT sensor in there. You will have to jump the oem oil pressure light switch connection. Don't worry, all this connection does is turn the gauge cluster oil pressure light on and off, it does not go to the ECU.

    The block adapter is M18 x 1.5 x 1/8"npt.

    I've tried several of them, so far the one I like the best is the Prosport PSNUT. Just be aware it comes with Teflon tape that you should remove and replace with high temp Permatex thread sealant.
    You can get the adapter here:https://www.rallysportdirect.com/par...hreaded-center

    IAG sells the adaptor with a kit to remote mount the sensor so it will last longer: https://www.iagperformance.com/Prosp...p/psropkit.htm I think a few other vendors sell the same kit.


    Credit to Underdog on the LGT forum for posting the instructions, I've copied them over here:

    - 1 Gallon Multi-Purpose Sprayer - I used the HDX 1 Gal, which I purchased for $8.97 at Home Depot.
    hdx-sprayers-1501hdx-64_1000.jpg


    - Qty.1 Barbed Hose Fitting - 1/4" Barb to 1/8" BSPT - Your HD might not have this exact configuration (mine didn't), so get creative. The fewer connections the better. *Note the factory bung is threaded BSPT and not NPT. Do not use an NPT fitting here!*

    Assembly:

    1. Open the sprayer box.

    2. Remove the sprayer from the box.

    3. Install the sprayer hose and pump/handle.

    4. Do not install the trigger/wand assembly.

    To use:

    w71tePZ.jpg

    A. Remove the oil pressure switch from the galley plug adapter. This is located under the alternator in the front center of the engine.

    B. Thread in your barbed fitting until hand tight, then cinch it down lightly with a wrench. Do not overtighten as you will easily strip the brass fitting.

    C. Push the hose from the sprayer onto the barbed fitting.

    D. Fill the tank with a gallon of whatever oil you prefer.

    E. At this point I usually remove the oil filler cap and start pumping. This particular sprayer has a built-in pressure relief valve which seems to open at about 30PSI. (When I first tried this I plumbed in a gauge to see how much pressure was being created.)

    F. Keep the tank pressurized until it is nearly empty. Try not to let it run down completely as you don't want to push a bunch of air in after the oil. It's not hyper-critical, just keep an eye on it.

    G. This really doesn't even need to be a step... but if you are curious how the oil is flowing you can try cracking the turbo oil feed banjo bolt loose. The oil will come out very quickly, so be prepared.

    H. When you are done you can release the pressure on the tank and pull the hose off the barbed fitting. The pressure in the galleys will cause a little back-flow, so either cap it until the pressure bleeds off, or work quickly and replace your oil pressure switch to minimize spillage.

    I. You can install a filter in the pump line to be extra sure you get clean oil in your engine.

    J. This can also be used for filling trannys and differentials.

    Protip: Do this with the engine on the stand so you can easily spot any leaks, and fix them if necessary.

    There you go! Don't forget to check the dipstick before startup and after the engine is warm.
    "Good Judgement comes from Experience. Experience comes from Bad Judgement"
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  15. #11
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    Thanks. That is really good info, especially the
    metric to npt adapters.

  16. #12
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    Or do what I did. Just don't tighten down the banjo bolt for the oil feed behind the timing cover. That way it purges itself and pukes a half quart all down the front of the engine and onto the garage floor. On second thought, don't do that. Don't do that at all. It sucks.

  17. #13
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    Step one is don't panic. If the engine has been assembled with assembly lube properly, then you have nothing to worry about; that's its job

    Occasionally, EJ engines can be stubborn to prime. Priming with a priming system works well on many engines, but I personally recommend against it with the EJs. From the few not-so scientific tests we've done, it can actually cause the pump to take longer to pressurize the system. EJs tend to self prime best when you remove as much resistance upstream as possible and filling the block with oil counters that. Yes you can show 'pressure' on a gauge with the engine not running, but the back flow valve in the filter keeps a nice big slug of air between the filter and pump. Even if the filter did not have a backflow valve, you're not going to get any decent amount of oil into the suction side of the pump. This is where assembly lube does it's job best.

    Along the lines of what Six Star mentioned... Remove plugs, remove filter, and crank. This should produce oil out the filter pad in short order (no more than a couple of 15 second cranks). Once oil comes out the filter pad, you're essentially done. The engine will now build pressure faster than your gauge can read it (unless you are old or dorky like me and run a mechanical gauge). Just start it.


    Some builders prefer the 'just start it' method. It's not my personal preference, but it does have its merits. The oil pump does have an efficiency range, and cranking speeds are not idea. So starting (cold start RPMs) brings the pump into the range of peak efficiency immediately. I've done this method as well with no ill effects. My sources tell me this is how Subaru does it as well.

  18. #14
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    Quote Originally Posted by killerbmotorsport View Post
    Some builders prefer the 'just start it' method.
    I've ruined an engine this way, If any engine builder told me to do this, I would not trust anything else they had to say.

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