GM 6.2L V8 EcoTec3 Coolant Outlet / Thermostat Housing 12674639 - Silverado / Sierra

Overview

A coolant outlet referenced to OEM 12674639 for GMC and Chevrolet Silverado cooling systems. Supplied as a replacement coolant outlet / thermostat housing 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 coolant outlet carries coolant away from the cylinder head and, on most installations, houses the thermostat that regulates when flow is allowed into the radiator. A cracked housing or a sticking thermostat shows up as a slow warm-up, temperature that climbs in traffic then drops at speed, coolant residue around the outlet, or a heater that blows cold at idle.

Specifications as documented

• Component: Coolant outlet / thermostat housing
• OEM part number: 12674639
• Engine: 6.2L Gen V V8 flagged in listing match
• Model years: Not stated in captured listing data
• Package contents: 1 x coolant outlet (thermostat inclusion not stated)

Compatibility

Engine: 6.2L Gen V V8 flagged in listing match. Vehicle applications recorded for this part: GMC and Chevrolet Silverado applications as stated by supplier. Model years: Not stated in captured listing data. OEM reference: 12674639. Fitment status recorded at the time of listing: supplier-declared oem number - thermostat inclusion and rating unconfirmed.

Installation

Drain the system before removal, clean both mating faces, fit a new seal rather than reusing the old one, and torque the housing evenly to avoid distorting a composite part. Refill with the specified coolant, bleed the system properly, and check for leaks after a full heat cycle with the heater open.

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.