GM 6.2L V8 EcoTec3 Engine Oil Pump 12657346 - Gen V L83 L86 5.3L 6.2L

Overview

A Gen V oil pump referenced to OEM 12657346, the earlier number in the pump family that serves 5.3L and 6.2L truck and SUV engines. Supplied as a replacement engine oil pump for the GM L87 6.2L EcoTec3 V8 and the closely related Gen V 6.2L applications noted below. This listing covers the component described here only; hardware such as bolts, seals and gaskets is included only where the specification list says so.

Function

The oil pump is the only component generating oil pressure, so its condition sets the ceiling for everything downstream. A worn pump shows up as low pressure at hot idle, a pressure warning at low engine speed, or noisy lifters that quieten as revs rise. Because the pump draws from the sump, a restricted pickup screen can mimic pump failure and should be ruled out before replacement.

Specifications as documented

• Component: Engine oil pump
• OEM part number: 12657346 (partial second number in truncated title)
• Cross-reference: 12686433 recorded by a GM parts retailer as superseding 12657346
• Engine: 6.2L Gen V V8 - L83 / L86 named in title
• Model years: Not stated in captured listing data
• Package contents: 1 x oil pump (pickup tube and screen not confirmed as included)

Compatibility

Engine: 6.2L Gen V V8 - L83 / L86 named in title. Vehicle applications recorded for this part: Chevrolet and GMC Gen V truck and SUV applications. Model years: Not stated in captured listing data. OEM reference: 12657346 (partial second number in truncated title). Fitment status recorded at the time of listing: oem number cross-checked to gen v 6.2l; l87 rpo not printed.

Installation

Replace the pickup tube O-ring and check the screen while the sump is off, prime the pump before first start, and confirm pressure with a mechanical gauge rather than relying on the dash display. Use the specified oil grade and a new filter. If the engine has run with low pressure, inspect bearings before returning it to service.

Fitment notice

Compatibility is stated for the GM L87 6.2L EcoTec3 V8 on the strength of the supplier listing and, where an OEM number is published, a parts-catalogue cross-check. GM built the 6.2L V8 in several forms, and L86, LT1, LT2 and LT4 components are not automatically interchangeable with L87 parts. Before ordering, confirm the engine RPO code and the original part number against the vehicle, and treat this listing as a guide rather than a substitute for that check. Specialist engine repairs should be carried out by a qualified technician.