Zero oil pressure after rebuild | FerrariChat

Zero oil pressure after rebuild

Discussion in '365 GT4 2+2/400/412' started by raemin, Sep 16, 2021.

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  1. raemin

    raemin Formula 3

    Jan 16, 2007
    1,853
    Lyon (FR)
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    R. Emin
    #1 raemin, Sep 16, 2021
    We have managed to crank again this engine, but it does not manage to build pressure on its own.

    Initially we disconnected the oil hose that's coming from the oil pump (see diagram) and primed the engine with a "marco" (turbowerkx) pump.

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    The pressure with this electric pump raised to 5kg (on the dashboard gauge). from then on I was pretty sure the circuit was properly working and the engine sufficiently primed. So we removed the electric pump placed the hose back to the exit of the oil pump and cranked the engine.

    After 15secs there is still no pressure on the system, so we decided to stop before damaging the engine. Any hint would be greatly appreciated.
     
  2. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #2 Steve Magnusson, Sep 16, 2021
    Last edited: Sep 16, 2021
    What model are you working on? (That figure doesn't seem to match any SPC figure for the models in this section?)

    Might get a little messy, but you could try leaving that hose off during starter cranking (not engine running) and see if any oil comes out (that would give the least resistance for the oil pump trying to "lift" the oil up the pick-up tube) -- if not, would have to think the oil pump is not turning or something in the pick-up tube isn't right.
     
  3. raemin

    raemin Formula 3

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    #3 raemin, Sep 16, 2021
    Last edited: Sep 16, 2021
    This is an abstract from the december 1979 400i part catalogue "TAV 15".

    My car is a 1981 400i gen1, quite similar to the diagram (one of the hose fittings is different but that's all).

    I was considering the messy approach (removing the hose and see if the oil is bleeding), but my mechanic is not ready (yet) to spill oil on the floor.
     
  4. samsaprunoff

    samsaprunoff F1 Rookie
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    #4 samsaprunoff, Sep 16, 2021
    Good day Raemin,

    I agree with Steve. You need to confirm that the oil is actually flowing via the efforts by the engine's oil pump. Depending upon the results you can then dig deeper. What a huge annoyance and aggravation for you and your mechanic!

    Cheers,

    Sam
     
  5. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #5 Steve Magnusson, Sep 16, 2021
    Weird -- the online SPCs on all of them (365GT4 2+2 thru 412) show the oil pressure relief valve is part of the front casting and not a separate assembly (although the 400i SPC is probably the 1982 400i SPC):
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    Is your oil pressure relief valve a separate assembly as in your TAV 15?
     
  6. raemin

    raemin Formula 3

    Jan 16, 2007
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    #6 raemin, Sep 17, 2021
    Last edited: Sep 17, 2021
    There are actually two devices : the oil bypass pressure regulator which can be seen in your diagram (part 59 to 65) and an external pressure relieve valve.

    1) The bypass does incorporate a "piston", it redirects the oil directly to the pump input (it's some kind of a closed loop). Got to agree however that my water pump and oil pump case is not like what's illustrated on TAV15, it does have a a protrusion for the pressure valve (just like your diagram).

    2) The external relief valve does incorporate a "ball", it redirects the oil to the sump. This one is just like TAV15.

    We've checked both actually.

    If you look at the picture I posted previously (https://www.ferrarichat.com/forum/threads/new-oil-lines.647896/#post-148099811) you can clearly see the external relief valve, but also a bit of the pressure regulator (top left corner of the photo). Will take a better picture.
     
  7. raemin

    raemin Formula 3

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    #7 raemin, Sep 17, 2021
    On the workshop manual (section C1) you can see the correct diagram, I mean the diagram of what is actually implemented in my car: pressure regulating valve (3) and pressure relief valve (4).


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    The only difference with my setup is that I have oil hoses with one straight argus fittings and three angled fittings whereas the diagram shows 2 straight & 2 angled. I doubt that the an angled fitting instead of a straight one next to the pressure relief valve would make such a mess, but with these delicate engines who knows...
     
  8. raemin

    raemin Formula 3

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    #8 raemin, Sep 17, 2021
    All the car needed was a full night of rest! I presume that all the oil we had pushed in the heads, finally flowed back in the oil pump? In any case, early this morning the engine was ready for its comeback. It did idle for 15minutes, perfect pressure & cooling.

    The kjets are totally off, the advance is equally bad, one power steering hose is dead, a few silent blocks are dry, the exhaust rubber rings are all gone, one exhaust manifold gasket is leaking: under normal circumstances this would make me mad, but for now I am happy !!!

    This being said I am afraid the car will not join Charbonnière Classic Rally tomorrow... They just accepted the modest Renault 5 as a last minute substitute, so there is still some hope for me 400i die-hard: I will have the opportunity to follow @rovexienus's fleet of V12...
     
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  9. SouthJersey400i

    SouthJersey400i Formula 3

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    #9 SouthJersey400i, Sep 18, 2021
    Better late then never: when you were cranking motor and not getting oil pressure, did you have the spark plus out? Few motors will build pressure on starter with plugs in and not firing. Plugs out allow motor to spin freely and most motors will build some pressure.
    Ken
     
  10. samsaprunoff

    samsaprunoff F1 Rookie
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    #10 samsaprunoff, Sep 18, 2021
    Good day Raemin,

    I am glad that your oil pressure has returned, but I think it may be prudent to find out why. I say this, as I simply cannot imagine that all of the oil was stagnant in the upper portion of the engine from anything you did prior... unless there was little oil in the engine to begin with. As you know these engines have a huge sump capacity and so it would be improbable that all of this oil would not have some significant portion in the sump and thus available for your oil pump.

    For whatever reason every time I had some strange issue suddenly disappear, the actual issue returned and caused me grief. I hope this is not the case for you, but given the time, effort, and $$$ you have invested in your car/engine it would make sense to see if you can find out what happened.

    Cheers,

    Sam
     
  11. raemin

    raemin Formula 3

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    #11 raemin, Sep 19, 2021
    Thanks guys. We did attempt to crank it without the oil plugs but it did not build pressure, hence the reason why we disconnected the radiator hose and used an electric pump so as to fill the heads with 5l of oil.

    When we refiled the head, we should have also poured some oil in the pump as I am afraid we created an air pocket that was sealed by the oil on top of the engine.

    There are many alternative possibilities that I do not like...
    1) some internals (spring, piston and shims of the pressure regulator) of the oil pump were lost so I had to buy used parts
    2) We've routed the oil lines differently in order to accommodate a bigger cooling fan
    3) I do use Dino oil for now which could make the situation worse

    In any case I think we will baby the car for quite a while: we've rebuilt this engine three times, I'd rather avoid a fourth iteration.
     

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