Chevrolet Cobalt Service & Repair Manual: Cylinder Head Overhaul

It is usually recommended to send head to machine shop for complete overhaul.
Cylinder head must be cool before removing it from engine. Cylinder head warpage can result if a warm or hot cylinder head is removed.
Place clean shop towels over exposed engine cavities. Carefully remove towels so foreign material is not dropped into engine.
Do not use metal scrapers, wire brushes, power abrasive discs or other abrasive means to clean sealing surfaces on aluminum heads. These tools cause scratches and gouges that make leak paths. Use a plastic scraping tool to remove all traces of head gasket. Aluminum surfaces are soft and can be scratched easily. Never place cylinder head gasket surface, unprotected, on a bench surface.
1. Remove cylinder head from engine as outlined in "Cylinder Head, Replace."
2. Remove valves from head as outlined in "Engine Valves, Replace."
3. Clean oil, dirt and old gasket material from cylinder head. When removing gasket material from head face on aluminum head, do not use a metal scraper, aluminum surfaces are soft and can be scratched easily.
4. Support cylinder head on a bench with gasket side up.
5. Inspect head face for warpage using a suitable straight edge. If warpage is present and is within manufacturer machining limits, send head to machine shop to machine surface of head face flat. If warping exceeds manufacturer machining limits, replace head.
6. Replace valve guides.
7. Grind valve seats as outlined in "Engine Valve Seat, Grind."
8. Ensure all measurements and sealing surfaces are within manufacturer specification.
    Crankshaft Seal R&R
    Removal 1. Raise and support vehicle. 2. Remove front tire and wheel assembly. 3. Remove front fender liner. ...

    Cylinder Head R&R
    Removal 1. Remove air inlet duct and resonator. 2. Disconnect IAC, TPS and MAP sensor. 3. Disconnect EVAP and PCV ...

    See also:

    Chevrolet Cobalt Owners Manual. Removing the Flat Tire and Installing the Spare Tire (All Models Except SS)
    1. Do a safety check before proceeding. See Changing a Flat Tire. 2. If your vehicle has plastic wheel covers, use the wheel wrench to loosen the plastic wheel nut caps. Once the plastic wheel nut caps have been loosened with the wheel wrench, you can finish loosening them with your fingers. ...

    Chevrolet Cobalt Owners Manual

    Chevrolet Cobalt Service Manual


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