Jump to content



Goofy Engine Oil Pressure - I'm Stumped


  • Please log in to reply
9 replies to this topic

#1 Starfighterpilot

Starfighterpilot

    Dirty Old Man

  • Moderators
  • PipPipPip
  • 4,368 posts
  • Gender:Male
  • Location:Buford GA
  • Interests:Keeping my Starion reliably scootin' down the road
  • Model:Starion

Posted 20 July 2016 - 10:34 AM

First off, for the Old Broads whole life I've changed the engine oil every 2000 - 2500 miles. I've NEVER run her out of oil. Up until 2 years ago I've always dropped the crank case oil pan and cleaned it every Fall.  Never had any metal in it.

Here's what suddenly started going on since one morning in Jan 2016:

Cold engine start up no matter what outside temp is - start engine, oil pressure comes right up to about 1/4 inch above OEM oil pressure gauge mid - mark @ 1250 engine RPM's.

As engine warms up and RPM's gradually come down to 950, no matter what outside temp is, oil pressure drops down to about 1/8 inch above guage low pressure mark. Ocassionally get lifter clacking @ 950.. Goose throttle oil pressure comes up fast to 1/4 inch above mid - mark.

Any engine RPM above 1500, oil pressure is around the mid - mark +/- 1/8 inch. In other words pretty damn good pressure for the miles on the engine.

The above oil pressures are for using Castrol GTX 20W-50 engine oil with the ZDDP additive.


What I've checked:

Replaced crankshaft rear oil seal. Front one doesn't weep.

Replaced oil pressure sensor with a new OEM sensor that I had rat holed. Cleaned it's electrical terminal.  No change in pressure indication.

Dropped engine oil pan twice. There was no metal in the oil pan using eyballs and a heavy duty magnet.

Pulled the engine valve cover and there was no metal shavings on the head surfaces using the same magnet and eyballs..

Checked the operation of the engine oil thermostat by using my handy dandy hand held laser infrared temperature sensor. Oil temperature change  across the engine oil cooler on a HOT Atlanta 96 degree day with the engine idling and the crankcase oil pan reading 200 0 F was:

Oil cooler Oil Inlet  200 0 F

Oil cooler Oil Outlet cycles around 150 +/- 5 0 F.

Engine coolant temp stays about 1/8 inch below the temp guage mid mark, even on the hottest of days.

Rolled out # 4 rod bearing and the bearing showed very little evidence of wear. Reinstalled it.

Oil pick up tube o-ring appeared to be tightly seated in it's cavity in the oil pump. Pick up tube mounting bolts were tight.

Because shes got good oil pressure at above idle RPM's I'm sort of ruling out that the oil pump gears are gauled or scored. However the oil pump relief valve spring might have gone to Starquest Heaven and is staying retracted.

This may be off the wall - I don't know what the factory clearance is between the oil pick up strainer and the oil pan is. Maybe the pick up tube is sitting too high above the oil pan and thereby sucking a little air. Anyone have a good engine with the crancase oil pan off? Could you measure the distance between the engine block oil pan seating surface to the bottom of the oil pick up strainer?

Anybody got any ideas of something i'm missing?

Other than this oil pressure BS, she's running fine. Using Trilogy injectors she's getting 20 MPG city, 24 MPG highway. Engine temp is right where it's supposed to be.

Thanks for any suggestions in advance.

KEN
88 Starion ESI-R SHP BSE/stock original owner 495K Miles

84 Starion ES RIP in 1987

66 Dodge Charger, Modified Original OEM 383/ 365 HP, 4-speed, Sure Grip, original owner, 113K HARD miles - Being Restored

76 Dodge PU, Modified 440/ 425 HP, 4 speed, Posi Dana 60 DIF, 675K Miles





#2 Funky Phil

Funky Phil

    Super Pooper

  • Members
  • PipPipPipPip
  • 6,394 posts
  • Gender:Male
  • Location:Hell's microwave TX
  • Interests:2 streaks of fire for 60ft when I leave.
  • Model:Conquest

Posted 20 July 2016 - 11:23 AM

Have you verified oil pressure with a mechanical gage?
I can't remember for certain, but isnt idle oil pressure spec 11psi? I know its low.

Is the lifter tick at idle a new issue or has it always done that?
10.95@122mph MoFuggin stickshift! https://m.youtube.co...h?v=8Q01UKt5q4U

Posted Image

#3 Starfighterpilot

Starfighterpilot

    Dirty Old Man

  • Moderators
  • PipPipPip
  • 4,368 posts
  • Gender:Male
  • Location:Buford GA
  • Interests:Keeping my Starion reliably scootin' down the road
  • Model:Starion

Posted 20 July 2016 - 12:10 PM

View PostFunky Phil, on 20 July 2016 - 11:23 AM, said:

Have you verified oil pressure with a mechanical gage?
I can't remember for certain, but isnt idle oil pressure spec 11psi? I know its low.

Is the lifter tick at idle a new issue or has it always done that?

No I haven't verified oil pressure with a mechanical guage. I know the pressure indicator is fairly accurate cuz the readings i'm getting are consistent with the readings ( with the exception of idle pressure) I had before this issue suddenly occured. And I changed the oil pressure sensor and got the same readings.

In the past my idle engine oil pressure always read about 1/8 inch below the guage's mid - mark no matter what the outside temps were.

The plain fact is, the Old Broad physically has low oil pressure at idle when she warms up. And it started happening out of the clear blue one morning after start/warm up. NO, I repeat no, prior occurence.

Never had lifter clacking before. And the occurence of clacking I get happens once in a blue moon. And that's only because my foot isn't on the pedal keeping engine RPM's above 1500 RPM's.

Thanks for the response.

KEN
88 Starion ESI-R SHP BSE/stock original owner 495K Miles

84 Starion ES RIP in 1987

66 Dodge Charger, Modified Original OEM 383/ 365 HP, 4-speed, Sure Grip, original owner, 113K HARD miles - Being Restored

76 Dodge PU, Modified 440/ 425 HP, 4 speed, Posi Dana 60 DIF, 675K Miles

#4 DieHARDmitsu.

DieHARDmitsu.

    Established Member

  • Members
  • PipPipPip
  • 1,819 posts
  • Gender:Male
  • Location:Orlando, Fl
  • Interests:Star Orion
  • Model:Conquest

Posted 20 July 2016 - 12:46 PM

On cold starts, do you get any sign/sound of a rod knock during the first couple of seconds? The sound can be faint and goes away quickly.

Edited by DieHARDmitsu., 20 July 2016 - 12:48 PM.

Posted ImagePosted Image

#5 creakyjoints

creakyjoints

    Established Member

  • Members
  • PipPipPip
  • 1,920 posts
  • Gender:Male
  • Location:Seattle
  • Model:Starion

Posted 20 July 2016 - 12:55 PM

I know on mine I had a problem with oil pressure at start up. Unless I primed to system I would get no pressure. Would have perfectly good pressure until it was turned off. Go to restart after sitting and no pressure. Turned out to be the pickup tube oring. Have you ever replaced the spring for the relief valve?
the dude in the honda said, i thought you said your car was slow, my response was.. well you said yours was fast so i guess we both lied.. haha

#6 speedyquest

speedyquest

    Established Member

  • Members
  • PipPipPip
  • 3,892 posts
  • Gender:Male
  • Location:La Crosse Wisconsin
  • Interests:bmx, cars, computers
  • Model:Starion

Posted 20 July 2016 - 02:50 PM

Hey Ken, sorry to hear your having some issues. It looks to me like your going about this in exactly the right way. I only have two thoughts.

1) I kind of doubt it's your oil pickup being to high just because I can't think of a situation where that could have changed other than oil pan damage which hasn't happened.

2) One place to maybe check would be oil check valve for the oil cooler? Maybe that is partially stuck and causing some odd behaviour?

I guess the only other thing you can probably do is install an aftermarket oil pressure gauge to check the pressure. It might be that your OEM sending unit is fine but the gauge in the dash is having issues.

I wish you luck man and keep us posted.

1987 Flatty Starion -- Widebody Conversion -- V-Mount Setup --  JDL Tubular Manifold  --  MX-6 Intake -- MS3-Pro -- AEM FPR  --  ARP head studs -- 3" hood exit exhaust -- Hahn Racecraft 16g --  Tial F38 Wastegate -- Tial Q Bov -- Short route piping -- 5 lug & LSD conversion -- Tubular Front End -- Manual Steering Rack Conversion -- Manual Brake Conversion -- Stack Digital Dash -- AEM UEGO -- D2 coilovers -- full GNT poly bushings & mounts -- four 8" rears -- car lightened significantly...  More to come!


Posted Image


Build Thread --->  http://www.starquest...opic=143564&hl=


#7 TexasQuest

TexasQuest

    Advanced Member

  • Members
  • PipPipPipPip
  • 8,675 posts
  • Gender:Male
  • Location:Sunnyvale, Texas
  • Interests:TSi's & VR4's
  • Model:Conquest

Posted 20 July 2016 - 07:50 PM

I agree with these guys to check it with a mechanical gauge. It's possible the gauge cluster or wiring is acting finiky.
88 Fiji Blue -Tsi
Zoom clutch, Fidanza flywheel, Stedebani shifter, KSport coilovers, ST swaybars, abs delete, a/c delete, cruise delete, JVE, BSEK, TEP steel brake lines, LSP braided cooler lines, CX Racing radiator,  MK1 silicone hoses, MK1 pullies, *DM hard pipes & intercooler,14G turbo, ported exh. manifold, MAF Translator, 3.5" GM maf, Turbo XS RFL bov, *DM 3" exhaust, Cusco front strut bar, TEP rear strut bar, Enkei 92's, HKS turbo timer, AEM wideband, AEM boost gauge, AEM oil pressure gauge, Hallman boost controller
Posted Image

View PostJohnnyWadd, on 04 March 2010 - 10:01 PM, said:

my shaft was big i dont know what your talking about.

#8 Dad

Dad

    Advanced Member

  • Vendors
  • PipPipPipPip
  • 8,123 posts
  • Gender:Male
  • Location:Niles,Ohio
  • Interests:One stock and one not!
    87 White Quest
    87 Shetland
    83 Starion- Chevy powered
    ___________________________
  • Model:Conquest

Posted 20 July 2016 - 08:41 PM

Yep, have to verify actual pressures.

#9 BC_99

BC_99

    Plays in traffic

  • Vendors
  • PipPipPipPip
  • 5,170 posts
  • Gender:Male
  • Location:Concord, NC
  • Model:Conquest

Posted 21 July 2016 - 05:58 AM

Ken, did you install a new pickup when you changed out the oil pan from getting the first one crunched? I'm wondering if that may have something to do with it? If it's an oil level thing, like the pickup being to high or bent and ducking air, you should be able to add a little bit of extra oil, and it should tell you what is going on there. I do agree with trying to hook up a mechanical gauge, to document the actual numbers. Call me if you need to bounce the ideas around.

BC
Steering coupler replacement U-Joints are available here...
http://www.starquest...howtopic=145280

Posted Image Posted Image Posted Image

#10 M Code

M Code

    Member

  • Members
  • PipPip
  • 352 posts

Posted 22 July 2016 - 10:05 PM

Yup...
U need to verify oil pressure with a mechanical guage..
Beware of aftermarket oil sending units like from SMP, I tried (3) different ones they were all different some read low others pegged the guage.  Finally got a Mitsu OE unit from Japan, no more issues.  Also note that the oil guage is damped so it does not bounce around and does take a short time to respond for indication...

Just my $0.02...  ;)




1 user(s) are reading this topic

0 members, 1 guests, 0 anonymous users