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360 V8 Oil Pressure |
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Trader
AMC Addicted Joined: May/15/2018 Location: Ontario Status: Offline Points: 6913 |
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Just because there is spring pressure on the pressure relief/bypass valve, does not ensure it's seated.
There is a thread were John advises opening up the relief bore to 9/16" just to ensure this. Ensure the relief plunger is seating with machinist blue or even a thin film of grease or anti seize. Otherwise 20 PSI cold would be a sizable leak path, possibly a missing gallery plug but likely not that large. Intake valley line is a possibility. Doubt the bearings on a fresh rebuild could leak that much. Oil pump clearance/scoring would likely not leak back that much oil cold either. Your looking at approximately 4 g/m leak.
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SC397
AMC Addicted Joined: Apr/30/2009 Location: Michigan Status: Offline Points: 5480 |
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I finally got the time to tear this one down to see what is up with it.
The first thing I did was run the oil pump with my drill to get a reading. This is a video of it. I got about 20 PSI with the drill. Then I drained the oil, pulled the pan and plastiguaged the Main and Rod bearings. The Main Bearings are King brand and plastiguaged at .0015" clearance. The Rod Bearings are King brand as well and they plastiguaged at about .0018/.0020" clearance. Time to tear it all the way down to see what else is going on.. As I was pulling the cam out I heard a "tink". Come to find out #4 cam bearing had walked out of the block. This has happened one other time in 117 engine builds (585 cam bearings). The other block was a 1973 block and this block is a 1987. I have heard this happening with a couple of other people as well with the same #4 bearing. Must be they had a issue every now and then in machining the #4 cam bearing housing. These were Dura Bond brand. So I installed a new set of Sealed Power cam bearings in with LocTite on the center 3 bearings. This is how I fixed the 1973 block and it has been on the road since the '80's. I also swapped out the King Rod Bearings for a set of Clevite brand. The Clevites run slightly tighter than the King brand. The Clevites plastiguaged more towards .0015" clearance. Time for the drill test again.. Here is a video of the engine running at idle up to temperature. Edited by SC397 - Feb/21/2023 at 12:09pm |
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brownspirit
AMC Addicted Joined: Mar/07/2009 Location: Georgetown, MA Status: Offline Points: 1021 |
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Glad to hear it is fixed, sorry you guys caught a bad break. Sounds like the issue was caught very early, and could have been a lot worse. Going forward, do you plan to use clevite cam bearings only, or a little loctite on all of them? I guess with as many as you’ve done, 2 issues doesn’t really establish a concerning pattern.
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69' BBB AMX 390/4-speed
69' s/crambler project 69’ International F210d Cummins/5+4 |
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SC397
AMC Addicted Joined: Apr/30/2009 Location: Michigan Status: Offline Points: 5480 |
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I don't plan on changing a thing. (Well except, I am still trying to retire) LOL!
The 1973 engine ran over a year on the streets before I tore that one down. They both had oil pressure, just low.
Even thought it turned out to be nothing that I did wrong, I am still glad that it wasn't one of those that I built and sent to Austria, England, Italy, Germany, or Sweden. |
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