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Cylinder Head Replacement From "Weekend Mechanic" episode WKM-103

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To replace a damaged cylinder-head gasket, the cylinder head must be removed from the vehicle. Figure B Figure C Figure D Figure E Figure F Figure G Figure H Figure I Figure J Figure K Figure L Figure M Figure N Figure O

The cylinder-head disassembly and inspection indicated that, not only does the head gasket need replacing, but the engine-head itself is cracked and must be replaced with a new one. In this segment, the engine accessory parts that were removed are attached to the new cylinder head, and the new head is installed in the vehicle.


Cylinder-Head Replacement

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.

• The new (remanufactured) cylinder head (figure A) was purchased earlier with the knowledge that replacement of the old head might be necessary. Once it arrives, the new cylinder head is inspected to insure that there is no shipping damage.
  
  
  
  
• A casting number is visible inside the head (figure B). This number is used to verify that this head will fit the engine that's in this vehicle.
  
  
  
  
• The re-assembly process is essentially the reverse of the process done earlier for the cylinder-head disassembly. At each step in the cylinder-head re-assembly, where a gasket is called for, a thorough cleaning and a manufacturer-specified application of a new gasket is done. A complete set of new gaskets for this type of vehicle costs between $75 and $100.
  
  
  
  
• To begin re-assembly, install the push-rod guides and push rods (figure C).
  
  
  
  
• Install the water outlet and thermostat housing (figure D), complete with a new gasket.
  
  
  
  
• Install the EGR-valve housing (figure E), again with a new gasket.
  
  
  
  
• Install a new manifold gasket (figure F), and re-install the manifold (figure G.
  
  
  
  
• The next step is to remove the old gasket from the engine block, clean and prep the surface. Before cleaning this area, the lifter galley (figure H) needs to be protected to ensure that contaminants aren't allowed to fall in during cleaning. Place a lint-free shop-towel down into the galley to keep dirt from falling into any of the openings.
  
  
  
  
• If the old gasket doesn't come off easily, use a scraper and carburetor cleaner to remove it. With the gasket removed, carefully scrape the surface of the engine block to make sure it is perfectly clean (figure I) so that it will form a good seal with the new gaket.
  
  
  
  
• Clean the mating surface of the exhaust manifold (figure J).
  
  
  
  
• Use cotton swabs to remove any liquid that may have gotten into the bolt holes (figure K). Water or other liquid that inadvertently gets left in these holes could cause a hydro-lock and might lead to a cracked head.
  
  
  
  
• Use a tap and die set to re-tap each of the bolt holes in the engine block. This is done to clean any carbon or other contaminants that might be present in the threads. Once you've determined the proper tap for the holes in your engine, insert the tap into the hole and gently turn it (figure L). Since this is simply a cleaning of the threads, the tap should turn fairly easily. Repeat the tapping process on all of the bolt holes. The reason for re-tapping is to ensure the proper torque can be applied when the cylinder head is reinstalled. Carbon or debris in the bolt holes could prevent proper torque-tightening and have an impact on engine performance.

  Important: If the tap doesn't turn easily, check and be sure you are using the proper size. Forcing an improperly sized tap into the hole could damage the head and lead to additional problems.
  
  
  
  

• With the tapping process complete and the threads all clean, remove the protective rags that were inserted earlier (figure M), and vacuum the surface of the block using a shop-vacuum and needle-nose attachment.
  
  
  
  
• With the surfaces completely clean, you can now install the new cylinder-head gasket on the engine block (figure N). Be certain that the gasket is oriented in the proper manner. Most are marked on one side with the word "UP" to ensure that the gasket is not installed upside-down. The gasket has holes that fit on dowels on the block, ensuring that the gasket is positioned properly.
  
  
  
  
• With the new gasket installed, gently lower the new cylinder head into position on the block (figure O). This will require the assistance of an assistant to ensure that the head is aligned precisely.

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