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OP low cold, OP normal warm

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Old 03-17-2017, 01:14 PM   #1
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Default OP low cold, OP normal warm

TBSS LS2. OP was normal 40psi cold/warm. Melling high volume, high pressure pump.

Heard a noise one day, very faint only on light accel 2.2k~ rpm. Did cylinder balance test, it was #6 piston. I pulled pan, polished the crank journal, made sure it specd out right before slapping a new bearing set in for that one rod only.

Took the rest of the caps off to ensure the other bearings were fine. All was good. Replaced motor mounts while I was in there.

Truck runs fine, pulls hard, no noise. But ever since I completed this a month or so ago, my OP has been acting strangely.

Typically, idle and cold, it's around 25psi. Drive it around for a while, at idle it's 40psi. Sometimes I drive it around for a while and it still goes back down to 25psi.

I re-used my pickup tube o-ring as it was only 1 year old.

Think that may be the case here? Kinda weird the only things I touched were rod caps, the one bearing half, and the pickup o-ring that could've affected pressure...

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Old Yesterday, 11:27 AM   #2
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Consider some trash/gunk in the oil pump bypass. Slight possibility that slightly undersized the journal causing a tiny internal oil leak(high clearance) and the clearance tightens up when it warms up. If you suspect the o-ring or similar, drive it hard, shut it down, and immediately check dipstick for air bubbles(aeration).

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