1HD-T engine with low oil pressure: Questions

Discussion in 'Diesel Tech and 24 volts Systems' started by rchalmers3, Mar 21, 2011.

  1. Hello all, I've been off this forum for awhile, having become addicted to playing with ex-military trucks (US 2.5t "deuce and a half" multi-fuel cargo trucks) for the past year or so. I am back on board with some questions regarding the motor in a Landcruiser a friend just bought.

    The vehicle is a 1997 HDJ80 (HDJ80L-GCMEX for those of you who can read Toyota speak) with the 1HD-T turbo diesel inline six with the H151F 5 speed trans.

    We bought the truck knowing the oil pressure read low on the factory gauge when the engine is at operating temp. BTW, indicated pressure is acceptable (and verified with a mechanical gauge to be good) with the engine cold.

    When we got it home I checked the readings with a mechanical gauge on a warmed up motor and sure enough we are only getting 7 psi @ idle and 25psi @ 2000 rpm. I can realize 35psi by revving the motor to 2700 rpm. Specs for this engine are minimums of 4psi @ idle and 35psi @ 2000rpm. Oil level is full on level ground. Filter looks new and oil color is.... well it looks like diesel engine oil!;)

    Questions:

    * Does the 1HD-T have any known oil pressure regulator issues (wear causing the plunger to hang, or plunger springs that weaken) that may be at cause or contribute to low pressure once the engine is warm?

    * Is it likely the Big End Bearings (BEB) problems known on this motor will account for most of the warm engine oil pressure loss or do the mains (or cam bearing surfaces) also wear and loosen up?

    * Are there any other important ideas or issues inherent to this motor for me to consider? Oil viscosity characteristics for example....

    First thought is to replace the unknown factor: the oil, to see what difference (if any) that makes.

    My second thought is to perform a replacement of the BEB's in car to restore oil pressure. I performed a search and read on some older threads there may be issues with the rod cap bolts and am wondering if that is really an issue or if folks are playing it safe. Anyone experienced on that?

    Thanks in advance for your knowledge and experience. For those of you who go gaga (can I say that anymore?) over Landcruisers with ambulance doors, I'll post some pics if you need your fix.

    Ta,

    Rick
    Last edited: Mar 28, 2011
  2. Dave 2000

    Dave 2000 SILVER Star

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    I replaced my BEB's and IIRC it did not alter pressure at all? You will find the write up in here somewhere. http://forum.ih8mud.com/80-series-tech/365673-my-lc-80-thread.html

    Also there is no excuse to have black oil in this engine, they are very clean running and the oil (once you have the internals of the engine clean) will only start to discolour as it approaches 5,000 miles?

    regards

    Dave
  3. Cheers Dave,

    How did the bearings you removed look and did you perform a plastigage test on your work?

    My point is to see if you know if you really restored tolerances or if you just had a good time laying on your back under the car!

    Rick
  4. landcrusher80

    landcrusher80 SILVER Star

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    Same here no change in oil pressure after the BEB change. My gauge reads low too after the engine reaches normal operating temp.

    LandCrusher80
  5. Thanks landcrusher, your experience normalizes what Dave 2000 related: BEB's do not equal increased oil pressure.

    Given the dramatic (threefold) change in oil pressure going from cold to warm engine, I am considering the possibility of oil viscosity changes due to oil quality, selection and condition. Therefore I will first replace the oil with new 30w oil for turbo diesels. I'll monitor the difference and post up my report.

    Cheers,

    Rick
  6. Tapage

    Tapage Club 4X4 Panamá SILVER Star

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    Rick ..

    My 1HD-T also have low oil pressure that was not affected by BEB's .. I already put in new idle oil pressure plunger and spring and that help raising the oil press but not on idle ..

    I'm using half synth Castrol 15W-40 down here ( the best that I can found here without jumping into full synth that it's mostly designed for new gasser engines ) and still have around 16 - 18 PSI @ idle @ 144°F oil temp ..
  7. SHREDwagon

    SHREDwagon SILVER Star

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    Hey Rick, How many km's on the engine? After you replace the BEB's and oil, third thought might be a compression test......

    Lots of reading over on 80sCOOL on low oil pressure and HD-T's.

    Thought all the later 80's came with 1HD-FT's?
  8. Enigma

    Enigma

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    I'm not sure I understand the "problem". From your readings with a mechanical gauge it's within factory specs.
  9. SHREDwagon

    SHREDwagon SILVER Star

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    At idle, yes. But 25 psi at 2000 rpm? For comparison, I'm almost double that.....
  10. VTCDN

    VTCDN

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    I'd like to know , HOW you know it's half ?
    Blended Synthetic is % of ?

    Marketing hog-wash.

    But 25 psi at 2000 rpm sounds low to me also.

    VT
  11. Tapage

    Tapage Club 4X4 Panamá SILVER Star

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    just coz I trust in marketing .. ;) and that's you can read ouside the box .. ( qt )

  12. SHREDwagon,

    There is 185,000 kilometers indicated. I am no expert on Toyota engines, other than to read what is on the build plate riveted to the body! I have not heard of 80sCOOL, thanks for the resource, I'll check it out.

    I drained the sump and refilled it with 10 qts of Castrol 30w turbo diesel rated motor oil.

    The oil I chose made no difference. The engine still has acceptable pressure when cold but drops significantly when it warms up. While I had no expectation that the oil would "fix" the problem, I did hope to see some alteration in the pressure measurements in order to better understand the relation between viscosity, pressure relief function and pressure loss through the clearances.

    Tapage,

    Thank you for posting your comments and results. Do you believe I made an error in using the 30w oil? Would a multi-viscosity synthetic provide better viscosity stability during temperature change?

    I will replace the oil pressure relief plunger and spring next. The access for changing the relief plunger and spring is very accessible and is the last "external" solution I have available.

    Thanks guys,

    Rick
  13. Tapage

    Tapage Club 4X4 Panamá SILVER Star

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    I believe so .. I whish we could have access to any full synth Diesel ( specifically designed for our old diesels ) 5W-50 or 10W-60 oil .. but that's just a dream down here ..

    The best I cant found and use it's the castrol hyporum semi synth 15W-40 .. but there is an mineral Castrol 25W-60 that I'm evaluating for my future ..

    Hey Rick .. I did that with my Alt out and I don't thing there is that much space there to said it's very accessible .. ;) but can be done ..

    report your result with the plunger and spring replacement ..
  14. prado t

    prado t SILVER Star

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    Just stick with 15W-40 or for you guys near the equator 20W -50
  15. Tapage

    Tapage Club 4X4 Panamá SILVER Star

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    I forgot to mention ..that IMOP the 25W-60 it's good for any old engine that it's mainly used to drive ( run ) long distances without town stop and go ..

    To me was too thick to my daily basics .. I love pretty close to my office and my 80 it's my DD so bunch traffic ligths, stop and go ..
  16. Thanks Tapage, I have seen and used the Castrol Hypuron oil in other vehicles. Esta muy caro, verdad! But this other oil of 20-60w I have never heard of.

    The plunger, spring and sealing washer are on order, coming from Japan by slow boat (30 days).

    I am optimistic about the relief valve and spring making a difference becaue the problem is only at higher revs, where the valve is supposed to function. At idle we are seeing acceptable pressure. I will post up results when I have them.

    Thanks to all,

    Rick
  17. Tapage

    Tapage Club 4X4 Panamá SILVER Star

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    here ..

    Castrol México - Castrol RX Viscus

    the guy ..

    [​IMG]

    did you already open to instpect your plunger ?

    for a quick solve you can add some washers to the spring to make it stiffer and that definately need to help with your oil pressure ..
  18. Dave 2000

    Dave 2000 SILVER Star

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    Have a look here Rick, I used a micrometer and the crank journals were all in spec and with no scoring or bad oval readings.

    http://forum.ih8mud.com/80-series-tech/378409-beb-just-observations.html

    BTW, the gauge and sensor on the 80's are not too accurate, I would run a master gauge on there for a couple of hours and get the 'real world' figures.


    regards

    Dave
  19. Tapage

    Tapage Club 4X4 Panamá SILVER Star

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    Rick can you share the part number and price you got for plunger and spring . ?
  20. Towpack

    Towpack

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    Yorkshire,England
    Minimum OP specs for the 1HD-T and FT engines is 4.3 psi @ 600rpm and 36psi @ 3000rpm, not 2000 so your figures are just about in spec. As has been said BEB's have little effect on OP. A relatively good OP when cold which falls away drastically when hot can be caused by worn main bearings and/or journals.

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