In this segment, service of the cylinder heads continues with the cylinder head disassembly including 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.
Engine-Head Disassembly
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.
- With the valve cover removed, loosen all of the rocker arms (figure A). The rocker arms must be loosened and push rods removed in order to remove the cylinder head. There's no need to take the rocker arms all the way off. Simply loosen them and turn them to the side so the push rods can come out.
- As you remove the push rods, place them in a cardboard template (figure B) to keep them in the proper order so they can be reinstalled in the proper locations later.
- Important: Since these used push rods are to be reinstalled, it's important that the be placed back in the original locations since the wear pattern on each rod and mating surface may be unique. Placing the push rods into incorrect locations may cause unnecessary wear later on.
- With the push rods removed, begin loosening and removing the head bolts (figure C).
- Consult your vehicle's service manual for the proper order and procedure for removal and reinstallation of the head bolts (figure D). Removing or replacing the head bolts in improper sequence can cause the engine head to warp.
- With all of the head bolts removed, and with the help of an assistant (or an engine hoist), carefully lift out the engine head (figure E).
- Place the engine head on a work surface for disassembly (figure F). With accessory parts removed, the head can be sent to the machine shop to have the gasket surfaces milled to ensure a smooth, clean mating surface for installation of the new gasket.
- In fact, with the head removed from the engine, all gaskets associated with the head will be replaced as part of this service -- including the manifold, EGR-valve and thermostat-housing gaskets.
- Remove the retaining nuts and lift off the intake manifold (figure G).
- Remove the EGR (exhaust gas re-circulation) valve assembly (figure H). The EGR gasket is removed and the mating surface is cleaned.
- Remove the thermostat housing (figure I), which also serves as the connection between the cylinder head and the upper radiator hose. This housing is typically sealed very tightly, so removing it may require some effort. Again, this gasket will be removed and the mating surface cleaned.
- Carefully remove the rocker arms one by one (figure J).
- Clean each rocker arm thoroughly, especially at the pivot point (figure K). Set the rocker arms aside in order so they can be reinstalled properly.
- With the rocker arms removed, inspect and clean the underneath side of the cylinder head. In our project, this revealed that there were two separate cracks in the cylinder head extending through the sparkplug gaps to the valves (figure L -- at the tip of the screwdriver). This type of damage indicates that the cylinder head will need to be replaced with a new one.
In the segment that follows, the engine accessory parts that were removed are attached to the new cylinder head, and the new head is installed in the vehicle.
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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