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Thread: Low oil presure on rebuilt c90-8

  1. #41
    Charlie Aileron's Avatar
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    MVC-002S.JPGMVC-015S.JPG
    Same thing happened to me years ago on a small Continental.
    Charles Aaron
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  2. #42

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    Hello Guys!!
    Men, i have installed in my Pa18 experimental a C90-8F overhauled and im with the following problem:
    When i start the engine the pressure gets 70Psi on 1000Rpm but when the engine is warming up the pressure goes falling down and when i get oil temperature at 90C the oil pressure reaches 20PSI at 2200RPM.
    Someone knows what is happening with my engine?
    The engine is zero hour from overhaul with standard sizes and with a new oil pump!
    This problem can be a wrong spring at oil relief valve??
    Thanks for help guys!!
    Hudson

  3. #43
    www.SkupTech.com mike mcs repair's Avatar
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    Check oil screen


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  4. #44

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    Seventy psi is too much. Spring should be adjusted for 60. Twenty is too low for cruise on a brand new overhaul. The spring/ relief valve are probably not the problem, since it seals on startup.

    However, if you just generally had low oil pressure, the dirt on that relief valve would be the first place to look. Since this thread started, I built up (with care) my Stroker, and at ten hours the pressure dropped. Piece of dirt on the relief valve. 100 hours now, and I get 50 at cold idle and above 40 at cruise, 180+ oil temp.

  5. #45

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    Hi guys!
    Thanks for tips! I checked oil screen and is clean!
    I'm gonna check the valve relief for some dirt.
    Its strange because it has pressure on start and until about 40 Celsius but then the pressure goes dpwn bellow 30 and stabilize at 20 and temp reaches 100Celsius...
    Guys, im running with AeroShell 100 Running due to breaking time, do you know if its normal to engine gets hotter in this fase???
    Thank you so much!
    Hudson

  6. #46

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    3 things, i can think of, bad oil pump number one and the easiest to fix, you say new oil pump what did you do there? was the accessory case brought back to spec? no 2, lots of clearance between the cam and case, always get the case halves lapped if you arent going to check the clearences. no 3, big clearences between the cam followers and case. somewhere when the oil gets thinner its getting by. (ALL JUST A OPINION!!)

  7. #47
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    Check the oil pressure gauge and line for snotty oil, clear the line of any crud. If there’s any in the line it probably made it to the gauge too. Those issues have given me a few gray hairs, and I was seeing the same indications on the gauge.
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  8. #48

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    Hi TempDoug, thanks for your suggestions!
    My accessory case was overhauled and the pump gears where new! But when we assembled the oil pump we dont took any measures so the pump can be a problem...

  9. #49

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    Hello CenterHillAg.
    Yes, im gonna do this! Clear the gauge and line, but do you think that any crud there would cause this effects on measure of oil pressure?? 70psi when cold and 20 when hot??
    Thank you!
    Hudson

  10. #50
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    My issue with the line and gauge was on an R985. First takeoff of the the day indicating 95 psi, by the time I landed 20 mins later it was indicating 70 psi and still dropping, and 10 psi at idle after landing. We blew the line out and put a new gauge in, and my normal psi numbers were back.

    There could definitely be more going on, but I like to start small and work towards the more expensive stuff when I have a problem.
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  11. #51

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    Quote Originally Posted by Hudsonedu View Post
    Hi TempDoug, thanks for your suggestions!
    My accessory case was overhauled and the pump gears where new! But when we assembled the oil pump we dont took any measures so the pump can be a problem...
    , it should be ok.
    if a certified place did the case and you put new gears in

  12. #52
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    Seen something similar a little while ago. A small piece of aluminum was stuck in the pressure relief valve. We tore the entire engine apart and didnít find anything, Figured it was left over from the machine shop. Iíve also seen twice where synthetic oil was added accidentally to miner oil during break inn. The filter clogged up with a crude jelly. Aero shell mineral oil and philips 20/50 donít mix


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  13. #53
    Gordon Misch's Avatar
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    Aero shell mineral oil and philips 20/50 don’t mix
    Very interesting. Any thoughts why? Any other documentation?
    Gordon

    N4328M KTDO
    My SPOT: tinyurl.com/N4328M (case sensitive)

  14. #54
    1piece@atime's Avatar
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    No documentation, also both planes had challenger lifetime oil filters. They were rental planes and the renters accidentally added the wrong oil.


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  15. #55

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    Hello guys!
    Today i changed my oil pressure indicator but not change! 80psi on startup and go decreasing at time the engine is getting hotter until 20psi at 100C...
    So, im thinking about change the mag timming, i timed mags as shows on manual, left with 26 degrees and right with 28 but im gonna try the both at 24 degrees like O200, my question is if i bring the mags to 24 degrees it would change engine temperature???
    Thanks for helping men!!!
    Hudson

  16. #56
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    Quote Originally Posted by Hudsonedu View Post
    Hello guys!
    Today i changed my oil pressure indicator but not change! 80psi on startup and go decreasing at time the engine is getting hotter until 20psi at 100C...
    So, im thinking about change the mag timming, i timed mags as shows on manual, left with 26 degrees and right with 28 but im gonna try the both at 24 degrees like O200, my question is if i bring the mags to 24 degrees it would change engine temperature???
    Thanks for helping men!!!
    Hudson
    The only correct timing is the one on the dataplate.

    Was your engine recently overhauled? What was the outside air temperature?

    What kind of plane?

  17. #57

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    Quote Originally Posted by behindpropellers View Post
    The only correct timing is the one on the dataplate.

    Was your engine recently overhauled? What was the outside air temperature?

    What kind of plane?
    Hi behindpropellers!!
    Was overhauled, i cleaned the cranckcase, got new cilinders, my cranckshaft where standard with brand new standard bearings! We used only camshaft, connecting rods and valve system parts like pushrods and rocker arms but all of they where in good conditions!
    Outside air temp about 30Celcius, im in Brazil!
    My plane is an experimental PA11!!!
    Thanks for help me man!!
    Hudson

  18. #58
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    Quote Originally Posted by Hudsonedu View Post
    Hi behindpropellers!!
    Was overhauled, i cleaned the cranckcase, got new cilinders, my cranckshaft where standard with brand new standard bearings! We used only camshaft, connecting rods and valve system parts like pushrods and rocker arms but all of they where in good conditions!
    Outside air temp about 30Celcius, im in Brazil!
    My plane is an experimental PA11!!!
    Thanks for help me man!!
    Hudson
    1) Your engine was possibly built too tight - as it runs the oil heats up and looses viscosity. Who built it? Did they use plastigauge to confirm clearances?
    or
    2) Your oil pump clearances may be too loose. Did you put new oil pump gears in it? How did the rear case look?
    Last edited by behindpropellers; 11-19-2018 at 04:59 PM.

  19. #59

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    Quote Originally Posted by behindpropellers View Post
    1) Your engine was possibly built too tight - as it runs the oil heats up and looses viscosity. Who built it? Did they use plastigauge to confirm clearances?
    or
    2) Your oil pump clearances may be too loose. Did you put new oil pump gears in it? How did the rear case look?
    Hi Behindproppelers!!
    So, an aircraft mechanic friend of mine that built the engine for me, we used micrometer to took measurements, i dont know what is plastigauge man.
    I belive in this problem of my oil pump clearences too, we used brand news oil pump gears but the case is a used case but looked ok for us. I think its the main problem...
    When we looked to our case, we saw that some guy putted one piece like a bearing inside the left oil gallery and the mechanic here talk to us that this metal piece is puted there when use a oil cooler, we tried to remove this piece from there but was impossible, and to avoid some problem, we connect the left oil gallery to right trough one hose, i dont know if it can be the problem but is other thing too... Bellow some pics of our engine and baffles made from the bowersflybaby site.

    IMG_5055.jpg

    IMG_5096.jpg

    194D2DF8-5D16-48E3-9DCD-FDE68E40D648.jpg

    IMG_5040.jpg

  20. #60

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    I bet that's the problem. Start modifying these engines and you never know . . . I think I mentioned a couple years ago that converting from dash 12 to dash 8 can cause a serious loss of pressure, unless care is taken to properly plug a gallery someplace near the oil pump. Not an expert; I would never waste a perfectly good dash 12 that way.
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  21. #61

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    how long is the propeller from one end to the other?

  22. #62

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    Quote Originally Posted by bob turner View Post
    I bet that's the problem. Start modifying these engines and you never know . . . I think I mentioned a couple years ago that converting from dash 12 to dash 8 can cause a serious loss of pressure, unless care is taken to properly plug a gallery someplace near the oil pump. Not an expert; I would never waste a perfectly good dash 12 that way.
    Noo, we dont changed to the -12, its -8F originally and we kept the oil gallery open in the accessory case!

  23. #63

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    Quote Originally Posted by tempdoug View Post
    how long is the propeller from one end to the other?
    Tempdoug, its a 72inch`s of diameter with 42inch of pitch.
    With that prop we got 2250 of static RPM, but on takeoff roll the engine dont get any rpm more, so we changed to other prop with 72inch of diameter and 43 inch's of pitch!

    Here some pics of the baffles finished.

    IMG_7288.JPG

    IMG_7287.JPG

    IMG_7353.JPG

  24. #64
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    I had a similar problem with a C90-8 in my PA11. Sent crankshaft to Rick Romens. They reground and sent back yellow tagged. What they did wrong was took out oil transfer tubes and didn’t put them all back in. Number 3 rod journal was getting any oil. Hard to notice unless you know what your looking for. Had good oil pressure cold but when it warmed up went down to 25 ish. Good lesson that a yellow tag doesn’t mean shxt.

  25. #65
    www.SkupTech.com mike mcs repair's Avatar
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    That thing In galley sounds like a restrictor, probably good... whatís the deal with the hose you added??? It sounds like a lack of volume issue. Must that hose be installed??? Whatís its purpose???


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  26. #66

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    Quote Originally Posted by mike mcs repair View Post
    That thing In galley sounds like a restrictor, probably good... what’s the deal with the hose you added??? It sounds like a lack of volume issue. Must that hose be installed??? What’s its purpose???


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    Hi Mike!
    Yes, our doubt was about if that restrictor restrict the oil to go to main bearing galey and flow trough to the left oil galley, so to do this "bridge" besides right and left gallery we added this hose...

  27. #67
    www.SkupTech.com mike mcs repair's Avatar
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    Quote Originally Posted by Hudsonedu View Post
    Hi Mike!
    Yes, our doubt was about if that restrictor restrict the oil to go to main bearing galey and flow trough to the left oil galley, so to do this "bridge" besides right and left gallery we added this hose...
    Thatís what I mean. You have too much flow, not enough volume to keep up with it. Is it common to add that hose? Or is that hose likely your problem?


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  28. #68

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    Quote Originally Posted by mike mcs repair View Post
    That’s what I mean. You have too much flow, not enough volume to keep up with it. Is it common to add that hose? Or is that hose likely your problem?


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    I dont think man, because there went the oil coller and with oil coller there are much more volume then only the house...
    I dont know if its a good idea try to remove the house and dont have oil trough right gallery...
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  29. #69

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    Hello guys!
    Today we tried to remove the front hose that we put to "bridge" left to right oil gallery, and nothing change... So we took off the oil pressure indicator and oil line, i flushed with air to clean and nothing too... So now im assuming that my instruments are ok and the problems wasnt in oil hose, so now im na look the oil sump tube and oil pump...
    Here some pics...
    48848983-6BCC-4565-9E38-7F1698A8EEF0.jpg

    Here 1.4kg/cm2 is the same as 20 psi and 2.8 is 40psi, and in that moment we where with 6minutes running engine, 5 minutes at 1000 to 1200 rpm and then 2000 rpm with 25psi and less then 40C temp....

  30. #70

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    Guys.
    I took off the oil sump and i saw some oil decent trough oil pump shaft, so i blow the oil tube and this happens:
    Its normal to leak oil there??

    E7E6680A-5276-4C39-8299-65422EAB2063.jpg

    A1DED091-FC33-4127-A1FE-0BB5150D455A.jpg

    2D9840EA-084E-4994-90CD-BC3B4017F936.jpg

  31. #71
    Mark Lund's Avatar
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    I purchased a C85 from an estate that had been assembled from "yellow tagged" parts including the case halves. I was given the yellow tags with the engine. It had good oil pressure until the oil warmed up and then it dropped drastically. Long story short, it took planing the case halves and line boring them to solve the problem.

  32. #72
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    Quote Originally Posted by Hudsonedu View Post
    Guys.
    I took off the oil sump and i saw some oil decent trough oil pump shaft, so i blow the oil tube and this happens:
    Its normal to leak oil there??

    E7E6680A-5276-4C39-8299-65422EAB2063.jpg

    A1DED091-FC33-4127-A1FE-0BB5150D455A.jpg

    2D9840EA-084E-4994-90CD-BC3B4017F936.jpg
    That cover should be lapped anytime you have the pump apart. Even new ones

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"

  33. #73

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    Guys i removed my acessory case.
    That what i found, the lower gear has a little gap and is demaged the lower wall:

    80101734-4CC0-456F-BEDD-948F22854963.jpg

    4CB76E0D-A6F9-4FD5-9F7E-2C0B1C587BB8.jpg

  34. #74

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    In the last picture you posted it looks like the oil is coming out the pump from a hole.....is that true?
    if so this is likely your problem. You shouldn't have substantial leaks like that out of your oil pump.
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  35. #75
    cubdriver2's Avatar
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    Send it to Divco and have them put bushings in. If they say it can't be certified tell them you don't need a yellow tag you just want it to work. Mines been fine for over 1000 hrs

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"
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  36. #76

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    Is that lower gear loose and moving around when you slide it into position without the other gear installed?
    By any chance was it installed dry on inital installation? If so that's probably wear marks from running without oil.
    Show us a picture of the oil pump cover, and where it was leaking from.

  37. #77

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    do what glen says and then it looks like you used some kind of a sealer between the cover and the housing, dont do that. i see a line there of some type. divco or aircraft specialties will make sure that surface on the case is flat, you need to make sure the cover for the gears is flat. looks like a aluminum case instead of magnesium which can be fixed, but the bottom gear bore and the sidewall of the pump cavity is toast. then ask yourself if the cam to case tolerances and cam follower to bore tolerences are in good shape also. fixing the accessory case will help but it might not be a total fix.
    Last edited by tempdoug; 11-21-2018 at 02:34 PM.
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  38. #78

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    Quote Originally Posted by tempdoug View Post
    do what glen says and then it looks like you used some kind of a sealer between the cover and the housing, dont do that. i see a line there of some type. divco or aircraft specialties will make sure that surface on the case is flat, you need to make sure the cover for the gears is flat. looks like a aluminum case instead of magnesium which can be fixed, but the bottom gear bore and the sidewall of the pump cavity is toast. then ask yourself if the cam to case tolerances and cam follower to bore tolerences are in good shape also. fixing the accessory case will help but it might not be a total fix.
    Hello men!!
    Ok, im gonna see what i will do in this case, put bushing on gear shaft or change this case to another one..
    I m gonna be sure that oil pump is ok and then if the problem persist open engine again!
    I made a movie but i dont know how to put here...
    Thanks guys for your help!!!
    Hudson

  39. #79

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    Quote Originally Posted by Pacerfgoe View Post
    Is that lower gear loose and moving around when you slide it into position without the other gear installed?
    By any chance was it installed dry on inital installation? If so that's probably wear marks from running without oil.
    Show us a picture of the oil pump cover, and where it was leaking from.
    Yes, is moving a lot man!!
    Here is the picture:
    001E80D7-38E9-4637-8A41-EF0494DFB468.jpeg

  40. #80

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    Tempdoug we used a chemical seal with a line like as engine seal in the oil pump cover, is this way wrong??
    Thank you!
    Hudson

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