GM 6.2L V8 EcoTec3 Timing Chain Kit 12646386 - Gen V with Tensioners and Guides

Overview

A timing chain kit referenced to OEM 12646386, supplied with tensioners, guides and sprockets for Gen V V8 timing repair. Supplied as a replacement timing chain kit 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 timing chain holds the camshaft in a fixed relationship with the crankshaft, so valve events stay synchronised with piston position. A worn chain, a tired tensioner or a polished guide allows that relationship to drift, and the first symptom is usually a cold-start rattle that fades as oil pressure builds, followed later by cam timing codes, rough running and a loss of power. Because the chain also drives the oil pump on this engine family, wear in the same group can show up as low oil pressure rather than as a timing fault.

Specifications as documented

• Component: Timing chain kit
• OEM part number: 12646386
• Cross-reference: 12646387 and 12586482 recorded as related numbers on a GM parts retailer page
• Engine: 6.2L Gen V V8 - L86 / L87 flagged in listing match
• Model years: Not stated in captured listing data
• Package contents: Kit with chain, tensioners, guides and sprockets as stated in the title; exact piece count not published

Compatibility

Engine: 6.2L Gen V V8 - L86 / L87 flagged in listing match. Vehicle applications recorded for this part: Gen V V8 applications as stated by supplier. Model years: Not stated in captured listing data. OEM reference: 12646386. Fitment status recorded at the time of listing: oem number cross-checked to 2020 silverado 1500 gen v application.

Installation

Timing work is a alignment job before it is a parts job. Bring cylinder one to top dead centre on the compression stroke, confirm the timing marks before anything is loosened, and check that every new part matches the parts removed. Replace tensioners and guides as a set rather than individually, use a new front cover seal, and rotate the engine by hand through two full turns to confirm the marks before the first start.

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.