CTS 2003-2005

Camshaft, Bearings & Lifters

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Inspection



Inspect the camshaft and lifters/followers as described earlier in this section.

Camshaft & Bearings

Clean the camshaft(s) in an appropriate solvent such as Safety-Kleen®. Dry the camshaft(s) with compressed air. Inspect the camshaft sprocket locating notch for damage or wear. Inspect the lobes and bearing journals for excessive scoring or pitting, discoloration from overheating and deformation from excessive wear, especially on the camshaft lobes. If any of these conditions exist, replace the camshaft. Measure the camshaft bearing journals for diameter and out-of-round using a micrometer. If the bearing journal diameter is smaller than 1.061 inch (26.948mm), replace the camshaft. If bearing journal out-of-round exceeds 0.0009 inch (0.022mm), replace the camshaft. If a lathe is available, a camshaft can be mounted between centers and checked for straightness. Camshaft runout cannot exceed 0.002 inch (0.051mm). No machining of the camshaft is allowed. In actual practice, if there is any question as to a camshaft's condition, it should be replaced.

3.1L, 3.4L (VIN E) & 3.8L Engines

Inspect all of the camshaft and drive components. Inspect the drive sprockets and chain. Inspect the keyway and threads on the camshaft. Check the cam lobes and the bearing surfaces for wear. The camshaft cannot be repaired, and, if damaged, must be replaced. Measure the camshaft journals with a micrometer and compare with specifications. Replace if worn. Camshafts normally operate with 0.001 inch (0.025mm) or less bearing clearance. If a lathe is available, a camshaft can be mounted between centers and checked for straightness. In actual practice, if there is any question as to a camshaft's condition, it should be replaced along with a complete set of lifters.

3.4L (VIN X) Engine

Inspect the camshaft for wear or deformation. Inspect the lobes for wear. Replace if necessary. Inspect the nose of the camshaft for brinelling from the lock ring. Pressure marks are acceptable. Grooves on the camshaft are not acceptable and the camshaft must be replaced. Inspect the carrier for scratches and/or burrs around the seal surface and also where the camshaft journals rest (bearing surfaces) on the carrier. Clean all the oil holes and inspect the bearing oil feed holes for metal debris, blockage and dirt. In actual practice, if there is any question as to a camshaft's condition, it should be replaced.

Camshaft & Followers

Inspect the camshaft(s) and followers as described earlier in this section.

Removal & Installation



3.1L, 3.4L (VIN E) & 3.8L Engines

The engine must be removed from the vehicle to service the camshaft.

  1. With the engine out of the vehicle, secure the engine in a suitable workstand.
  2.  
  3. Remove the rocker cover, the rocker arms, the pushrods and intake manifolds using the procedures found in this section
  4.  
  5. The roller lifters use guide plates to keep the lifters from rotating off of the cam lobes. Remove the lifter guide bolts and remove the lifter guide. The lifters can be pulled from their bores. All lifters must be removed before the camshaft can be pulled out.
  6.  


WARNING
Any valve train parts that have been removed with the intention of reinstallation must be marks so that they can be returned to their original locations.

  1. Remove the oil pump drive. This is a stub shaft located in the back of engine in the location where the distributor resided in older versions of this engine. It is driven by a gear on the camshaft and is necessary to drive the oil pump. Like a distributor, it is retained by a hold-down clamp. Remove the clamp and lift the oil pump drive straight up and out of the engine.
  2.  
  3. Remove the crankshaft balancer and the engine timing chain front cover, following procedures found in this section.
  4.  
  5. Remove the timing chain and camshaft sprocket, following procedures found in this section.
  6.  


WARNING
All of the camshaft bearing journals are the same diameter so care must be used when removing the camshaft so the sharp edges of the cam lobes do not gouge the soft metal of the camshaft bearings.

  1. Remove the two screws that hold the camshaft thrust plate to the block and remove the thrust plate.
  2.  
  3. Insert a large screwdriver in the camshaft to act as a handle and to help support the camshaft as it is withdrawn from the block. Pull the camshaft out slowly, rotating the camshaft to help it clear the bearings.
  4.  
  5. Normally, if an engine requires a new camshaft, it likely also needs a complete overhaul. In actual practice, the engine block is stripped of components and sent to an automotive machine shop where the block can have the cylinders refinished or overbored and other checks can be made. Most shops will "hot-tank" the block in a caustic solvent for thorough cleaning. The solution in a hot tank destroys the soft metal in camshaft bearings. In nearly every case, as part of their engine block prepping service, the automotive machine shop will install new replacement cam bearings. If, for some reason, you choose to attempt camshaft bearing replacement yourself, the following should be helpful.
    1. A special tool called a Camshaft Bearing Remover/Installer is required. This tool normally consists of a bearing driver and a number of different size expanders, or collets to hold the bearings of a wide variety of engines. These tools vary in quality and cost but are all designed to install the bearing straight, parallel to the engine's centerline. This type of tool can often be rented. Use great care if using substitutes since the block can easily be damaged beyond repair with use of improper tools and methods. Note too, that sometimes if a defective lifter wears a just a lobe or two, and not too much metal has circulated in the oil, it may be possible to replace a camshaft and use the original bearings without removal. Typically, camshaft bearings show little wear, especially in contrast to connecting rod bearings or crankshaft main bearings.
    2.  

  6.  


NOTE
Camshaft bearings, once removed, must never be reinstalled.

  1. Remove the camshaft rear cover (plug). This is a round plug, similar to a so-called "freeze-plug." The engine flywheel must be removed to access the rear camshaft cover (plug).
  2.  
  3. From a camshaft bearing remover tool kit, select the expander assembly and driving washer. Install the tool into the camshaft bore and drive out the bearings, one by one.
  4.  



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Fig. Internal components that must be removed before the camshaft can be pulled out-3.1L, 3.4L (VIN E) and 3.8L engines



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Fig. Remove the thrust plate and pull out the camshaft-3.1L, 3.4L (VIN E) and 3.8L engines



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Fig. Camshaft rear cover (plug). Install flush to the block or slightly recessed, as shown-3.1L, 3.4L (VIN E) and 3.8L engines



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Fig. Typical camshaft bearing removal and installation tool

To install:

  1. Clean all parts well. If the camshaft bearings were removed, examine the bores in the block. Note that there are oil holes which MUST line up with the oil holes in the bearings or the camshaft will quickly fail. Severe engine damage will result if the oil holes are not correctly aligned. If the camshaft bearings were removed, and you attempting to install them, use the following as a guide. A short piece of 3 / 32 inch brass rod with a 90 degree bend in the end, or an appropriate size Allen® wrench can be used to probe the bearing holes to ensure the holes are proper aligned with the holes in the block. Use care not to scratch the bearing surfaces.
    1. With the new bearings, select the proper expander and driver washer from the camshaft installation kit.
    2.  
    3. Index the camshaft bearing oil hole so it will line up with the oil hole in the block.
    4.  
    5. Install all of the intermediate camshaft bearings first. Make sure the oil hole in the bearing lines up with the oil hole in the block.
    6.  
    7. Install the #1 camshaft bearing. Make sure the oil hole in the bearing lines up with the oil hole in the block.
    8.  
    9. Install the #4 camshaft bearing. Make sure the oil hole in the bearing lines up with the oil hole in the block.
    10.  
    11. Apply sealer, GM #12345493, or equivalent, to the camshaft cover (rear plug) and install the plug until flush with the engine block.
    12.  

  2.  


WARNING
All camshaft journals are the same diameter so care must be used in removing the camshaft to avoid damage to the bearings.

  1. Coat the camshaft bearing journals with engine oil or engine assembly lube. Coat the camshaft lobes with GM lubricant #1052365. Special cam lobe lubricants are also available. The reason a camshaft needs special attention with its lubricant is that it is usually a long time between camshaft installation and initial start-up. This is especially true on front wheel drive vehicles where the engine must be removed and installed. Thin lubricants will drain away. Camshaft lubes or special oils like GM Engine Oil Supplement (EOS) will cling to the camshaft lobes. In addition, camshaft lobes are lubricated by crankshaft and connecting rod throw-off oil. When an engine first starts, it may not run fast enough to supply the oil needed to lubricate the camshaft lobes. A special camshaft lube protects a new camshaft in the first few critical minutes at start-up and break-in. Do not neglect to properly lubricate the camshaft or it could be ruined in minutes.
  2.  
  3. Start the camshaft into the bore. Often, with all the lube on it, it can be too slippery to handle conveniently. Some technicians will temporarily install the cam drive sprocket to give them something to grip. Turn the camshaft as you install it and use care to keep the camshaft lobes from gouging the soft metal of the bearings.
  4.  
  5. Install the thrust plate and torque the screws to 89 inch lbs. (10 Nm).
  6.  
  7. Lubricate the driven gear of the oil pump driven gear assembly with GM lubricant #1052365. Coat the rest of the assembly with clean engine oil. Install the oil pump drive and tighten the hold-down bolt to 27 ft. lbs. (36 Nm).
  8.  
  9. Install the timing chain and sprockets using the procedures found in this section.
  10.  
  11. Install the remainder of the components in the reverse order of assembly.
  12.  

3.4L (VIN X) Engine

The 3.4L (VIN X) engine uses a direct-acting Double Over Head Camshaft (DOHC) layout. Motion is transmitted from the camshaft lobe through the hydraulic lifter directly to the valve tip. The camshafts are not interchangeable. The right (rear) camshafts are shorter than the left (front) camshafts.

The aluminum camshaft carriers each contain one intake and one exhaust camshaft. The actual aluminum in the carrier serves as the camshaft bearing surface. The camshaft thrust plates, which control the camshaft location, are mounted on the rear of the carriers.


WARNING
Timing must be reset if the camshaft sprockets are removed from their shafts. Pins or keys are not used to establish camshaft to crankshaft timing. Please refer to the Timing Belt Removal and Installation and Cylinder Head Removal and Installation procedures for more information, cautions and the special tools required.

  1. Remove the camshaft carrier using the procedure found under Cylinder Head Removal and Installation.
  2.  


WARNING
Keep the valve lifters in order so the lifters may be installed in their original locations.

  1. Remove the lifters.
  2.  
  3. Remove the oil from the camshaft hold-down tool hole in the camshaft carrier. Install tool J 38613-Camshaft Hold-down Tool or exact equivalent.
  4.  
  5. Remove the camshaft sprockets.
  6.  
  7. Remove the rear cover plate (also called the thrust plate cover) and gasket. Remove the thrust plate bolts and the thrust plates.
  8.  
  9. Remove the camshaft hold-down tool.
  10.  


WARNING
All camshaft journals are the same diameter so care must be used in removing the camshaft to avoid damage to the bearings. In addition, there are no removable bearings since the camshafts ride in the aluminum camshaft carrier.

  1. Carefully remove the camshaft out of the back of the camshaft carrier.
  2.  
  3. Pry out the oil seal using care not to damage the aluminum surfaces around the seal.
  4.  



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Fig. Exploded view of the camshaft and cam carrier arrangement-3.4L (VIN X) engine

To install:

  1. Clean all parts well. Coat the seal and the camshaft lobes and journals with GM's #1052367 Engine Oil Supplement (EOS), or equivalent camshaft lube. This is very important.
  2.  
  3. Install a replacement oil seal using a suitable driver.
  4.  
  5. Install the camshaft to the carrier, working from the rear of the carrier. Use care not to damage the seal.
  6.  
  7. Inspect the thrust plates and locate the marking arrow. Install the thrust plates with the arrow on the thrust plate "UP". Torque the thrust plate bolts to 89 inch lbs. (10 Nm). Using a new gasket, install the thrust plate cover. Torque the thrust plate cover bolts to 89 inch lbs. (10 Nm).
  8.  
  9. Lubricate the lifters with GM's #1052367 Engine Oil Supplement (EOS), or equivalent camshaft lube. Install the lifters. From shop stock, cut and install six pieces of rubber hose under the camshaft and between the lifters to hold the lifters in the carrier. The exhaust side uses six pieces of tubing 3/16 x 6 inches long. The intake side uses six pieces of tubing 5/32 x 6 inches long.
  10.  
  11. Install the camshaft carrier to the cylinder head using the procedure found under Cylinder Head Removal and Installation.
  12.  
  13. Remove the oil from the camshaft hold-down tool hole in the camshaft carrier. Install Camshaft Hold-down Tool J 38613, or exact equivalent.
  14.  
  15. Install the camshaft sprockets. Please refer to Timing Belt and Sprocket Removal and Installation found in this section.
  16.  
  17. Install the remaining components in the reverse order of removal. Pay particular attention to the information in this section on timing belt installation since this retimes the sprockets to the camshafts. Please see the Timing Belt and Sprocket Removal and Installation procedure. This is most important.
  18.  

3.5L Engine

The four overhead camshafts are driven by three separate 8mm, single-row, fine pitch chains. The primary drive chain connects the crankshaft with both large intake camshaft sprockets, the balance shaft sprocket and the intermediate shaft sprocket. The exhaust camshafts are driven by short chains from the intake camshafts. Primary timing chain tension is held by a tensioner that hydraulically applies pressure to a pivoting tensioner shoe/chain guide. The intake-to-exhaust camshaft chain tensioner contains an internal spring that provides a constant load on the secondary timing chains.


WARNING
This engine is constructed primarily of aluminum. Use care when working with light alloy parts. Fasteners which thread into aluminum must not be over-torqued or damage to the threads may result. Tighten specifications must be strictly observed to assure proper gasket sealing. When cleaning gasket surfaces on aluminum or magnesium parts, tools specifically designed for these materials should be used. Soft wire brushes and dull scrapers are recommended to prevent gouging of the machined surfaces. In order to obtain valid bolt torque readings, excessive oil or coolant accumulations in the bolt holes should be avoided. Blow out the bolt holes using compressed air prior to installing the fastener.



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Fig. View of camshaft holding fixture J 42038 installed on the camshafts-3.5L (VIN H) engine



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Fig. Use the flats on the camshaft if rotation is necessary for installation of the holding tool-3.5L (VIN H) engine



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Fig. Before installation, compress the tensioner and lock it in place with a piece of wire-3.5L (VIN H) engine



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Fig. Camshaft identification-3.5L (VIN H) engine



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Fig. The sprockets and chains slide off the camshafts onto this fixture-3.5L (VIN H) engine



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Fig. Camshaft bearing cap identification-3.5L (VIN H) engine



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Fig. Camshaft removal-3.5L (VIN H) engine



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Fig. Secondary camshaft sprocket drive chain and alignment pins-3.5L (VIN H) engine


NOTE
In general, this procedure can be used for both the left side (front) and right side (rear) camshafts.

  1. Partially drain the cooling system into a suitable container.
  2.  
  3. Rotate the crankshaft until the engine is positioned at Top Dead Center (TDC) for number 1 cylinder (right side, rear bank, forward cylinder) on the compression stroke (firing position)
  4.  


WARNING
Special Tools J 42038 Camshaft Holding Fixture, J 42042 Timing Chain/Sprocket Holding Fixture and J 36660-A Electronic Angle Meter, or their exact equivalents, are required for this procedure.

  1. Disconnect the thermostat housing for access to mount special tool J 42042 Chain/Sprocket Holding Fixture.
  2.  
  3. Remove the camshaft cover using the procedures found in this section.
  4.  


WARNING
You must install the J 42038 Camshaft Holding Fixture immediately after cam cover removal. This tool prevents unexpected camshaft rotation caused by valve spring pressure.

  1. Install special tool J 42038 on the camshafts. When properly installed, this fixture will be fully seated on the camshaft ends with the camshaft flats parallel to the cam cover sealing surface.
  2.  
  3. If working on the right side (rear) camshafts, remove the camshaft position sensor.
  4.  
  5. Remove the camshaft sprocket bolts.
  6.  
  7. Install special tool J 42042 on the cylinder head. Evenly slide the secondary drive chain and camshaft sprockets off the camshafts and onto J 42042. This fixture keeps the sprockets and chain in tension and in the correct relationship.
  8.  
  9. Observe the markings on the camshaft bearing caps. Each bearing cap is marked to identify its locations. It is important that the bearing caps be installed in their correct locations. Look for:
    1. The raised feature on the camshaft bearing cap must always be oriented toward the outboard of the engine.
    2.  
    3. The letter I indicates the intake camshaft.
    4.  
    5. The letter E indicates the exhaust camshaft.
    6.  
    7. The number indicates the journal position from the front of the engine.
    8.  

  10.  
  11. Remove the camshaft bearing cap retaining bolts and remove the bearing caps. Use care to note the position of each bearing cap. Store them in such a way that there will be no mix-up at assembly. The cap closest to the front of the engine is the thrust cap and must not be installed in any other location.
  12.  
  13. Remove special tool J 42038 from the camshafts. Allow the camshaft lobes to find a neutral position by rotating each camshaft, if necessary. DO NOT rotate the camshafts more than 10 degrees. Lift the camshafts from the engine. To prevent corrosion, the camshafts should be covered by an oil soaked shop towel while they are out of the engine.
  14.  
  15. If necessary, remove the camshaft followers. Keep them in the order in which they were removed and store in a clean place.
  16.  

To install:

  1. Clean all parts well. Inspect the camshaft and all related components. If there is any question as to a component's condition, replace the part.
  2.  


WARNING
The camshaft follower must be positioned squarely on the valve tip so that the full width of the roller will completely contact the camshaft lobe. If the camshaft followers are being reused, you must put them back in their original locations.

  1. If the camshaft followers were removed, apply a liberal amount of clean engine oil or engine assembly lube to the valve lifter roller, the lash adjuster and valve tip areas of the camshaft followers. Place the camshaft followers in position on the valve tip and lifter. The rounded head end of the follower goes on the lash adjuster while the flat end goes on the valve tip.
  2.  
  3. Verify that the No.1 cylinder is still at TDC of its compression stroke (firing position).
  4.  
  5. Select the proper camshafts for installation noting the following:
    1. The left side (front) cylinder head camshafts are longer than those on the right cylinder head.
    2.  
    3. Both sets of camshafts share the same placement of identification rings. However the identification ring for the intake camshafts is between the first and second sets of lobes. The identification ring for the exhaust camshafts is located between the second and third sets of lobes.
    4.  

  6.  
  7. Apply a liberal amount of clean engine oil or engine assembly lube to the camshaft journals and cylinder head camshaft carriers.
  8.  
  9. Place the intake and exhaust camshafts in position in the cylinder head.
  10.  
  11. Position the camshaft lobes in a neutral position with the front notch for the camshaft sprocket drive pins neat the top of their rotation and the rear flats of the camshaft near the installation position of Special Tool J 42038.
  12.  
  13. Observe the markings on the camshaft bearing caps. Each bearing cap is marked to identify its locations. It is important that the bearing caps be installed in their correct locations. Look for the following:
    1. The raised feature on the camshaft bearing cap must always be oriented toward the outboard of the engine.
    2.  
    3. The letter I indicates the intake camshaft.
    4.  
    5. The letter E indicates the exhaust camshaft.
    6.  
    7. The number indicates the journal position from the front of the engine.
    8.  

  14.  
  15. Install the camshaft bearing thrust caps in the first journal of each camshaft. The thrust caps are wider than the others and have machined undercuts not present on the other caps. Make sure the orientation marking is closest to the engine valley. Install the remaining bearing caps with their orientation mark closest to the engine valley. Hand start all of the bearing cap bolts.
  16.  
  17. Tighten the camshaft bearing caps to just 71 inch lbs. (8 Nm). Use J 36660-A or equivalent torque angle meter to tighten the bolts an additional 22 degrees.
  18.  
  19. Using the hex cast into the camshaft, rotate the camshaft so that the rear camshaft flat is facing the cylinder head. It should not be necessary to rotate the camshaft more than 10 degrees. Install J 42038 Camshaft Holding Fixture at the rear of the cylinder head. The camshafts must be locked in place using this fixture before installation of the secondary timing chain.
  20.  
  21. Compress the secondary timing chain tensioner shoes with your hand. Lock the tensioner by inserting a piece of wire into the access hole in the side of the tensioner. Slowly release pressure on the tensioner shoes. The tensioner should remain compressed.
  22.  
  23. Slide the intake and exhaust camshaft sprockets off of special tool J 42042 and onto their respective camshafts and align the drive pins in the camshafts. With the sprockets correctly in place, remove tool J 42042 from the cylinder head. Tighten the camshaft sprocket bolts to 18 ft. lbs. (25 Nm) then, using a torque angle meter, tighten the bolts an additional 45 degrees.
  24.  
  25. Remove the locking wire from the secondary timing chain tensioner allowing the tensioner shoes to expand and apply pressure to the timing chain.
  26.  
  27. Remove tool J 42038 from the camshafts.
  28.  
  29. Install the front camshaft cover and the thermostat housing, following procedures in this section.
  30.  
  31. Install the remaining components in the reverse order they were removed.
  32.  

 
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