ION, L-Series, S-Series 1999-2005

Cylinder Head

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General Information



There are two basic types of cylinder heads used on today-s automobiles: the Overhead Valve (OHV) and the Overhead Camshaft (OHC). The latter can also be broken down into two subgroups: the Single Overhead Camshaft (SOHC) and the Dual Overhead Camshaft (DOHC). Generally, if there is only a single camshaft on a head, it is just referred to as an OHC head. Also, an engine with a OHV cylinder head is also known as a pushrod engine.

Most cylinder heads these days are made of an aluminum alloy due to its light weight, durability and heat transfer qualities. However, cast iron was the material of choice in the past, and is still used on many vehicles today. Whether made from aluminum or iron, all cylinder heads have valves and seats. Some use two valves per cylinder, while the more hi-tech engines will utilize a multi-valve configuration using 3, 4 and even 5 valves per cylinder. When the valve contacts the seat, it does so on precision machined surfaces, which seals the combustion chamber. All cylinder heads have a valve guide for each valve. The guide centers the valve to the seat and allows it to move up and down within it. The clearance between the valve and guide can be critical. Too much clearance and the engine may consume oil, lose vacuum and/or damage the seat. Too little, and the valve can stick in the guide causing the engine to run poorly if at all, and possibly causing severe damage. The last component all cylinder heads have are valve springs. The spring holds the valve against its seat. It also returns the valve to this position when the valve has been opened by the valve train or camshaft. The spring is fastened to the valve by a retainer and valve locks (sometimes called keepers). Aluminum heads will also have a valve spring shim to keep the spring from wearing away the aluminum.

An ideal method of rebuilding the cylinder head would involve replacing all of the valves, guides, seats, springs, etc. with new ones. However, depending on how the engine was maintained, often this is not necessary. A major cause of valve, guide and seat wear is an improperly tuned engine. An engine that is running too rich, will often wash the lubricating oil out of the guide with gasoline, causing it to wear rapidly. Conversely, an engine which is running too lean will place higher combustion temperatures on the valves and seats allowing them to wear or even burn. Springs fall victim to the driving habits of the individual. A driver who often runs the engine rpm to the redline will wear out or break the springs faster then one that stays well below it. Unfortunately, mileage takes it toll on all of the parts. Generally, the valves, guides, springs and seats in a cylinder head can be machined and re-used, saving you money. However, if a valve is burnt, it may be wise to replace all of the valves, since they were all operating in the same environment. The same goes for any other component on the cylinder head. Think of it as an insurance policy against future problems related to that component.

Unfortunately, the only way to find out which components need replacing, is to disassemble and carefully check each piece. After the cylinder head(s) are disassembled, thoroughly clean all of the components.

Removal & Installation




WARNING
Only remove the cylinder head when the engine is cold. Warpage may result if the cylinder head is removed while the engine is hot.

  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Drain the cooling system.
  4.  
  5. Drain the engine oil.
  6.  
  7. Properly relieve the fuel system pressure.
  8.  
  9. Remove or disconnect the following:

    Negative battery cable
     
    Intake manifold
     
    Exhaust manifold
     
    Timing chain
     
    Cylinder head bolts using the proper sequence
     
    Cylinder head
     

  10.  

To install:

Click image to see an enlarged view

Fig. Cylinder head bolt loosening sequence


NOTE
Set the crankshaft to 60 degrees Before Top Dead Center (BTDC) or after Top Dead Center (TDC) to prevent contact between the pistons and valves.

  1. Install or connect the following:

    New cylinder head gasket
     
    Cylinder head and align it on the dowels
     
    New cylinder head bolts and torque them in sequence to 22 ft. lbs. (30 Nm) plus 155 degrees
     
    Front 4 cylinder head bolts coated with Loctite® and torque them to 26 ft. lbs. (35 Nm)

    Click image to see an enlarged view

    Fig. Cylinder head bolt tightening sequence



    Click image to see an enlarged view

    Fig. Location of the 4 front cylinder head bolts

     
    Timing chain
     
    Exhaust manifold
     
    Intake manifold
     
    Negative battery cable
     

  2.  
  3. Fill the engine with clean oil.
  4.  
  5. Fill the cooling system.
  6.  
  7. Prime the fuel system by cycling the ignition ON for 5 seconds and OFF for 10 seconds a few times without cranking the engine.
  8.  
  9. Start the engine, check for leaks, and repair if necessary.
  10.  

2.2L Engine

WARNING
Only remove the cylinder head when the engine is cold. Warpage may result if the cylinder head is removed while the engine is hot.

  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Drain the cooling system.
  4.  
  5. Drain the engine oil.
  6.  
  7. Properly relieve the fuel system pressure.
  8.  
  9. Remove or disconnect the following:

    Negative battery cable
     
    Intake manifold
     
    Exhaust manifold
     
    Timing chain
     
    Cylinder head bolts using the proper sequence
     
    Cylinder head
     

  10.  

To install:

Click image to see an enlarged view

Fig. Cylinder head bolt loosening sequence-2.2L engine


NOTE
Set the crankshaft to 60 degrees Before Top Dead Center (BTDC) or after Top Dead Center (TDC) to prevent contact between the pistons and valves.

  1. Install or connect the following:

    New cylinder head gasket
     
    Cylinder head and align it on the dowels
     
    New cylinder head bolts and torque them in sequence to 22 ft. lbs. (30 Nm) plus 155 degrees
     
    Front 4 cylinder head bolts coated with Loctite® and torque them to 26 ft. lbs. (35 Nm)

    Click image to see an enlarged view

    Fig. Cylinder head bolt tightening sequence-2.2L-ION



    Click image to see an enlarged view

    Fig. Location of the 4 front cylinder head bolts-ION

     
    Timing chain
     
    Exhaust manifold
     
    Intake manifold
     
    Negative battery cable
     

  2.  
  3. Fill the engine with clean oil.
  4.  
  5. Fill the cooling system.
  6.  
  7. Prime the fuel system by cycling the ignition ON for 5 seconds and OFF for 10 seconds a few times without cranking the engine.
  8.  
  9. Start the engine, check for leaks, and repair if necessary.
  10.  

 
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