| Cylinder Head Service -- Diagnosis and Preparatory Steps |
From "Weekend Mechanic"
episode WKM-103 |
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"Blown head gasket" are words no car owner wants to hear. But the situation isn't necessarily as catastrophic as it sounds. Diagnosing potential problems with the engine cylinder head, accessing gasket surfaces and replacing gaskets isn't all that difficult provided you have the right parts, the right tools and go about the process correctly. However, if you let this engine problem go unchecked, it will result in major damage and the need for very costly repairs. The problem: Our project car -- which has a 4-cylinder overhead-valve engine -- is leaking coolant and has overheated a couple of times. Upon visual inspection, leaking coolant is visible pooling on top of the engine block in the area of the head gasket. DIY Difficulty Rating for Repair: Diagnosing and repairing a cylinder head is a substantial project. The process is fairly time-consuming, probably requiring about 12 hours of work. (Your project time may vary according to your vehicle's make and model, and the exact nature of the problem.) It's a fairly ambitious undertaking, but can probably completed in two full days of work, provided that the necessary replacement parts are on hand. We give this project a difficulty rating of 3 on a 5-point intermediate-level scale. Important: Included below are the steps in this automotive procedure as shown in the episode. These steps are general guidelines that are applicable to most vehicles. With any particular vehicle, there may be procedures, specifications, settings, tolerances, components, etc. that are specific to that vehicle. Always consult your vehicle's service manual when undertaking significant automotive repairs. In addition to standard auto-mechanic's tools, some of the specialty tools (figure A) that will be needed for this project include a cylinder-compression test kit and tap and die set.
Preparatory Steps
- Begin by removing the hood (figure B) and conduct a visual inspection. Check hoses, connections, gaskets, etc.
- Our inspection revealed a leaky head gasket (figure C -- at the tip of the screwdriver) indicated by coolant pooling on the top of the engine. The leak is sizable. The repair called for in this situation is to remove the cylinder head and replace the gasket.
- The first preparatory step is to drain the radiator. Use drain pans, and use floor absorbant to soak up any spilled coolant (figure D).
Safety Alert: Always clean up spilled antifreeze right away. It is toxic to humans and animals, and has a sweet odor that may attract pets.
- Disconnect and remove any hoses, air intakes, plug wires, etc. that you may need to in order to access the valve cover and cylinder head (figure E).
Important: Read your vehicle's service manual to get information on proper disassembly procedures.
- Tip: Since you'll probably need to remove a number of parts to access the head, you may want to take a photo or home video of the engine before you begin work to use as a reference later.
- Remove the valve-cover retaining bolts and carefully lift off the valve cover (figure F).
- With the valve cover removed, the valves and rocker arms are revealed (figure G).
In the segment that follows, the cylinder head disassembly begins with removal of the push rods and head bolts. The engine head is then removed and broken down further with removal of the intake manifold, EGR valve, thermostat housing and rocker arms.
RESOURCES :
The Complete Idiot's Guide to Trouble-Free Car Care
Author: Dan Ramsey
ISBN: 0028635833
Alpha Books
How Cars Work
Author: Tom Newton
ISBN: 0966862309
Publisher: Black Apple Press
Auto Repair for Dummies
Author: Deanna Sclar
ISBN: 0764550896
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