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Old 08-11-2019, 11:12 AM   #1 (permalink)
Low Boost
Join Date: Aug 2019
Location: Fort Worth, Texas
Posts: 7

Low oil psi after rebuild

This is my first post on this website. Amazing knowledge here on these 6.5's. I have a 96 Chevy 3500 4x4 that dropped an oil cooler line and ended up spinning a mail bearing. The machine shop said the block was bad so I got a 99 block and rebuilt the motor with all new parts. The motor runs great with the oil psi at 40 until it warms up then it drops to 20 psi a 2000 rpm and about 8psi at 1000 rpm. Here is the kicker. I put an oil pump for a 1996 6.5 (Mellings M55I) but the 1999 motor calls for a Mellings M255-294S. Could this be what's causing the low oil pressure after the truck warms up. I know it can be a lot of things but guess I'm hoping I just need to change the oil pump. Any thoughts?


96' Chevy K3500 6.5L

Last edited by OkDually; 08-11-2019 at 11:22 AM. Reason: prefix/sig
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