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Decrease in oil pressure

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Old Jun 21, 2020 | 07:01 PM
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Decrease in oil pressure

Riddle me this batman. So without numbers on engine compression or leak down and such. Take a look at the following. THe line in Green was my rain race back in March. The REST of the lines are much faster laps in the dry this past weekend. Ever since the march race I've been experiencing oddly low oil pressure measured at the filter housing like it always has. Cold startup used to be 100, but now it's 60. However when I did pulls it went into 60's so I figured it should be ok. However when comparing the data, it tells another story:




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Old Jun 21, 2020 | 10:17 PM
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Lower oil pressure under all conditions usually means there's a bearing on its way out. Get an OCA done on the oil and see what the metal content is like.

Hopefully that's not the case but at work I deal with this exact scenario about once a month or every other month and almost every time it's a bearing that's about to say sayonara.
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Old Jun 22, 2020 | 06:58 AM
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Yea that looks like a bearing issue. I would check before you pump a bunch of metal through the motor.
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Old Jun 22, 2020 | 07:26 AM
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As the other two said, likely bearings. Get an oil analysis done, or cut a filter open. It'll tell you..
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Old Jun 22, 2020 | 07:32 AM
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Gaaahhhh. No matter who builds it or what qualify parts you put in, nothing ever lasts as long as oem. Shoulda snagged a few short blocks while they still existed.

Best case - could you drop the pan and replace the bearings. If there's a ton of shiny bits I know it's a rebuild, this was a one off Curt Brown block. So that isn't gonna happen, sigh.
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Old Jun 22, 2020 | 07:44 AM
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It's entirely possible you caught it before any major damage could occur. That's the beauty of having oil pressure data.

If so, get the crank polished, grab some new COATED tri metal bearings and throw it back together (measuring everything of course).
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Old Jun 22, 2020 | 07:58 AM
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Well least the new cooling works. New personal best using the new CSF core and 2 fans. Wicked hot out, 90, 130 track. No ducting.


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Old Jun 22, 2020 | 08:42 AM
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2 rad fans? Which ones are you running? Are all your coolers center mounted?
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Old Jun 22, 2020 | 09:21 AM
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Originally Posted by ayoustin
2 rad fans? Which ones are you running? Are all your coolers center mounted?
OEM oil cooler still so it's over there. Oil temp didn't get above 244 before the sensor broke off. CSF rad is the kit you get from CSF, the 7075 one "designed" by Sheeply. So it's that their 12" own 950cfm SPAL fan sitting on the inside right, then I slapped my old 1750cfm SPAL 13" one on the front left where I've always had it. STM wants 1k bucks for theirs and it's no different....
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Old Jun 22, 2020 | 09:22 AM
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King XP or ACL bearings?
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Old Jun 22, 2020 | 09:35 AM
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I've used King, ACL and Clevite in 4Gs. I was a tad annoyed my King bearings came covered in metal dust but a copious amount of brake clean got them clean.

Both are reputable. Both use similar coatings. Go with whichever you can get most easily.

I've heard from machinist friends that King tends to be a couple ten thou more consistent on shell thicknesses but that's kind of splitting hairs.
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Old Jun 22, 2020 | 10:27 AM
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Did evoscan display oem location oil pressure? I can't remember.
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Old Jun 22, 2020 | 10:30 AM
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Originally Posted by Balrok
Did evoscan display oem location oil pressure? I can't remember.
OEM oil pressure is just a switch.
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Old Jun 22, 2020 | 10:36 AM
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Originally Posted by Balrok
Gaaahhhh. No matter who builds it or what qualify parts you put in, nothing ever lasts as long as oem. Shoulda snagged a few short blocks while they still existed.

Best case - could you drop the pan and replace the bearings. If there's a ton of shiny bits I know it's a rebuild, this was a one off Curt Brown block. So that isn't gonna happen, sigh.
How many miles would you say are on it? Do you know what clearances curt used when he assembled it?

As Austin said, since you caught it early you may be able to get away polishing the crank and new bearings.
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Old Jun 22, 2020 | 11:32 AM
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Ahh I see it now. So this is the rain race in March when I kept blowing out that rear PCV fitting. It went out of spec on the back straight looks like, building up speed in 4th.



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