300tdi oil pressure mystery after rebuild





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  1. #1
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    Default 300tdi oil pressure mystery after rebuild

    Hi all,

    We recently did a rebuild of sorts on a 300tdi which was really just a freshen up with new rings and bearings in the end.

    Anyhow, upon starting there was no oil pressure. This was confirmed with a mechanical gauge, where we got absolutely no pressure at all.

    Cranking with the oil pressure switch off shows that there is oil flow.

    https://youtu.be/hZeyLqbFhms

    So it seems as if there is something wrong elsewhere which is causing no resistance and preventing pressure build up. We are confident all the bearings were the correct size.

    We then overfilled the engine with oil to see if we could get it up and flowing but no luck.

    After that, we rigged up a pump with a gauge to the oil switch oil to try to check if the relief spring setup operated correctly at the 55 psi it is supposed to but we couldn't get it to hold any pressure at all.

    So the sump came off and the plunger and relief spring were confirmed as put in correctly.

    Basically there seems to be a leak in the system somewhere preventing resistance necessary to build up pressure as the pump appears to be providing adequate flow (or at least enough to provide some level of pressure..)

    We are at our wits' end so any assistance would be greatly appreciated!

    Cheers,

    Jim.

  2. #2
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    Default Re: 300tdi oil pressure mystery after rebuild

    Pull all the bearing caps and check the bearing clearances with Plastiguage
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  3. #3
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    Default Re: 300tdi oil pressure mystery after rebuild

    Head gasket correct and channels not blocked?

    Oil pick up securely fastened and seal/o-ring in place?
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  4. #4
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    Default Re: 300tdi oil pressure mystery after rebuild

    Some of the engines I've rebuild took 5-6 3 second swings with the starter to get the oil pressure.

    Old trick on the V8 was to pack the pump with vasiline.

    It primes the pump faster amd dissolves in the oil.
    '07 Land Rover Defender 110 TDI 300 Kalahari (Meisiekind˛)
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  6. #5
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    Default Re: 300tdi oil pressure mystery after rebuild

    Any engine rebuild needs a new oil pump.

    But this is the clue: "new rings and bearings in the end"

    somebody stuffed up. too much bearing clearance to the crank and big ends
    2012 Jeep Sahara Unlimited 3.6 V6
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  8. #6
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    Default Re: 300tdi oil pressure mystery after rebuild

    Quote Originally Posted by jelo View Post
    Any engine rebuild needs a new oil pump.

    But this is the clue: "new rings and bearings in the end"

    somebody stuffed up. too much bearing clearance to the crank and big ends
    Very possible, wouldnt be the first time. Pump doesnt create pressure, its the restrictions within the system that does
    Estee = S T = Sean Towlson

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  9. #7
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    Default Re: 300tdi oil pressure mystery after rebuild

    Quote Originally Posted by jfh View Post
    Some of the engines I've rebuild took 5-6 3 second swings with the starter to get the oil pressure.

    Old trick on the V8 was to pack the pump with vasiline.

    It primes the pump faster amd dissolves in the oil.
    I had forgotten about that old trick
    Estee = S T = Sean Towlson

    Hummer H3 V8

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  10. #8
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    Default Re: 300tdi oil pressure mystery after rebuild

    Could be bearings clearance, cam bearings, oil spray nozzel left off to cam vacuume pump lobe or even oil squirt nozzles, pick up sucking air in
    or even excessive pump clearance and filter housing obstruction
    One will have to go through it and check
    Last edited by clivemd; 2019/07/10 at 08:00 AM.
    1995 300TDi Defender with VGT Turbo (stolen by my son now )
    2002 Defender with LS1 MS3 ECU, 4L80e, LT230 1.222, Lockers and HD CW&P, 35" with 4" Lift
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  11. #9
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    Default Re: 300tdi oil pressure mystery after rebuild

    Also what was the oil pump and crank cut always like, on the crank there are flats cut away that pump slots over to drive pump were they all still good not worn, resulting in crank spinning but no movement on pump,
    1995 300TDi Defender with VGT Turbo (stolen by my son now )
    2002 Defender with LS1 MS3 ECU, 4L80e, LT230 1.222, Lockers and HD CW&P, 35" with 4" Lift
    2005 Defender TD5

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