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oil pressure and destruction

Discussion in '80-Series Tech' started by robbie, Mar 8, 2004.

  1. robbie

    robbie Guest

    Hello and goodday:
    I found my problem and why my I lost oil pressure. I have never replace a oil pressure relief spring in my long years rebuilding engines and will now do it until I can get a spring tester. I have for a long time seen my pressure drop when I hit 3500-3800 and with my old engine had hooked up a mechanical oil pressure guage and found that the guage was at fault. Well with the new engine (assembled with different parts from stuff I had aquired) I did not pay real close attention to it when I saw this problem. Mistake number one.
    after working the engine hard (jsut like before, for close to 3 years), I saw the oil pressure guage drop with high RPM's and did not think any thing of it until driveing around town the pressure was staying low. Mistake # 2. that is when I found bits in the oil filter and parked my truck until I tear in to it.
    Well when I tore in to it I found #4 main real messed up and not much damage done to the crank. The down stream rod bearing did not get any of the bearing material, so it was fine. The bearing material went side ways and fell into the pan and made its way back to the oil filter. No futher damage to any bearing. But I did replace all bearing when I had the pans down.
    I got it all back together and and drove it with a after market guage installed and found that oil pressure droped off after 3000 rpm. I should of listened to the little bells long ago. So after shiming the relief valve and getting better pressure and shifting the pressure drop to higher rpms with the shims. I tried another spring from a wrecked 97 and found the relief worked fine no drop off of pressure at high rpm's. I had found the problem, a weak oil pressure relief spring. So I ordered one and will have a new one soon.
    So if you see oil pressure build and then fall off at higher RPM's I would suggest either just replacing the spring or getting a external guage and plumbing it in to see what is up or it could cost you the same it cost me (or more). A ten dollar part cost me well over 200 in parts and lots of labor.
    Observation I have seen on the stock oil pressure guage is that the first slash from the bottom mark is aoubt 25 PSI the second mark is about 50 psi, the last mark is 75 psi. oil pressure at idle is at or above 4 psi, the oil pressure at 3000 rpm is 34-71 psi.
    I am busy the rest of the day and want to get this posted so other if they have the same problem could catch it before it cost you. I do not have time to answer any question till I look at the list. This will happen tomorrow I believe. learning all the time, some lessons cost more than others. later Robbie
     
  2. Beowulf

    Beowulf

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    Robbie,
    Thanks for sharing this information. We have one forum member (lars) that has his engine apart right now and he's removing the timing chain cover. I'll post a link to this thread over in his post so he's sure to see this and replace the spring while he is in there.

    FWIW, C-Dan replaced his oil pressure relief spring when his engine was apart. I'll post pics if anyone is interested in what these things look like.

    -B-
     
  3. hpantier

    hpantier

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    i would like to know what they look like for sure.
     
  4. Lars

    Lars

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    Thanks B. After talking to Robbie earlier today, it looks like I may have more work to do.

    Cdan,

    Can you add this part to my order placed today? Do you need me to call?
     
  5. cruiserdan

    cruiserdan SupportingVendor Emeritus Moderator

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    I also replaced the valve and the washer.

    1FZ spring, 15132-66020, list $1.17
    " valve, 15131-46040, list $3.20
    " gasket, 15134-17010, list $1.17

    4 bucks is pretty cheap compared to an overhaul.
     
  6. Beowulf

    Beowulf

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    Hank,
    I think there's a pic somewhere of the valve & the spring. The spring is on the wooden block in this one.

    [​IMG]

    -B-
     
  7. cruiserdan

    cruiserdan SupportingVendor Emeritus Moderator

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    [quote author=Lars link=board=2;threadid=12750;start=msg117380#msg117380 date=1078779160]
    Thanks B. After talking to Robbie earlier today, it looks like I may have more work to do.

    Cdan,

    Can you add this part to my order placed today? Do you need me to call?
    [/quote]

    Handled.
     
  8. RavenTai

    RavenTai

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    how deep do you have to go to replace the valve and spring? I dont guess we would luck out and have it externaly accesable? I have not noticed any pressure problems but if it is easy to get to might be good PM
     
  9. cruiserman

    cruiserman

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    I didn't replace mine when I rebuilt the motor. I will do so when I go back in to fix the oil leak up front.
     
  10. cruiserman

    cruiserman

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    [quote author=RavenTai link=board=2;threadid=12750;start=msg117476#msg117476 date=1078790052]
    how deep do you have to go to replace the valve and spring? I dont guess we would luck out and have it externaly accesable? I have not noticed any pressure problems but if it is easy to get to might be good PM
    [/quote]

    Actually it's quite accessible. On the head gasket thread, see the big hex bolt on the right side of the timing cover, next to the oil pump cover?
     
  11. Pitbull

    Pitbull

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    WOW, I don't think I've ever gone over 3000 rpm for more than a second or two :)
     
  12. landtoy80

    landtoy80

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    So can it be replaced without pulling the timing cover?
    Do you have to remove the oil pump cover?
     
  13. cruiserdan

    cruiserdan SupportingVendor Emeritus Moderator

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    You do not need to remove the cover. Remove the bolt and the spring and valve will come out.
     
  14. landtoy80

    landtoy80

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    Sounds like cdan is going to get a phone call or two.
     
  15. Beowulf

    Beowulf

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    He'll feed a LOT of dogs at $4 a pop including shipping. :D

    -B-
     
  16. cruiserdan

    cruiserdan SupportingVendor Emeritus Moderator

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    Who said it included shipping? :flipoff2:
     
  17. landtoy80

    landtoy80

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    $4 times (how many80 owners are there on this list?)
    You need to give robie a kick back.
     
  18. RavenTai

    RavenTai

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    [quote author=cruiserman link=board=2;threadid=12750;start=msg117490#msg117490 date=1078792375]
    Actually it's quite accessible. On the head gasket thread, see the big hex bolt on the right side of the timing cover, next to the oil pump cover?
    [/quote]


    good deal, yep that looks like a good PM job,


    I wonder why the oil pressure only dropped at high RPM's??? it would seam a weak spring would cause a consistent lower relief pressure, all that is at work there is oil pressure one side of the valve spring pressure on the other the stronger wins and moved the valve open/closed the change over point is what the oil pressure is regulated to, where/why does RPM come in?
     
  19. ppc

    ppc M Go Blue

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    Rav..

    I tend to agree that if it was just the spring it would be more linear. If the valve/spring was misaligned or sticking might better explain what happened. We need Robbie to test the three springs (original, old replacement and new replacement) to see if there is any difference.
     
  20. robbie

    robbie Guest

    It is really hard to misalign the spring. THe relief piston is smooth and not marked up or scored (this might indicate sticking). The only thing I have done is switch springs. I do not have a spring tester. I really do not know what is up, in all the years I have rebuilt 22r's I have never had a problem (similar design of oil pump and relieft system). Rpm's come in to play with the spining of the rotor and ring creating more pressure as it spins faster. With the new spring and a couple of shims I left it created over 100 psi (had me worried I would have the dreaded CDAN oil leak happening). With no shims in I get a steady 12 psi at idle and and 60 psi at 2400 rpm, at 3200 it regulates at 75 psi and holds steady at that all the way up to redline. I am a happy man now. Now when I rebuild an engine I usually hot tank all steel parts and this may create some problem witht he spring (one thought). I currently have a customer that needs his spring replaced becasue when he pull the passes he is at 3600 rpm and he sees his oil pressure guage drop. I will replace his when I see him next.

    I did not means to cause a run on springs, the post was to keep people informed on what casues stuff. I really do not think people need to replace this spring unless there is a problem, besides I want my springs that I have ordered to get to me (the selfish me). Dan, I hope you do not have an override on orders that allows you to get the stock before me. (kidding). Catch you later robbie