2004 GMC Envoy XL Camshaft Replacement Cost

Camshaft failure will not allow use of the vehicle beyond the immediate future. In fact, when a camshaft fails, the engine will likely refuse to crank, start, or turn one direction by hand. If one lobe of the camshaft has become worn, the vehicle may be able to start, run and drive, but this condition will eventually lead to total engine failure as metallic debris is constantly being shaved from the crankshaft and sent through the engine oil channels. This needs to be corrected right away, as does any internal engine damage

Camshafts are not notorious for failure, but some european vehicles have been known to fail due to camshaft driven high pressure fuel pumps in as little as 20,000 miles. Besides design flaws causing issues for camshafts, the likelihood of camshaft failure for most vehicles is extremely low when the engine is properly maintained. In order to prolong the life of your engine camshaft, and all other components of the engine longblock assembly, changing the oil on time, never running low, and avoiding harsh driving should all be common practice. By following these simple rules, the engine camshaft should last the life of the vehicle.

Since the camshaft can fail by seizing or by flattening out a lobe, the technician will either receive a vehicle that runs terribly and misses on one or more cylinders repeatedly. If the engine will not crank or start, the technician will notice that the starter engaged with good battery voltage, but could not turn the engine. The engine will be turned by hand, and the technician will find they can not turn the engine. At this point, the engine is declared seized, but removal of the timing chain or belt must be done to verify if the camshaft or crankshaft has seized. If the engine cranks, but cranks quickly and without pulsation, the timing belt or chain will be inspected. If mission, the camshaft will be turned by hand, but will likely be seized. Finally, if the vehicle runs rough, the technician will begin by reading on-board diagnostic trouble codes, will find misfires on likely one cylinder, and will begin diagnostics by testing several other components. The ignition coil, spark plug, fuel injector and fuel injector seals will be tested. Afterwards, engine vacuum leak testing may even be conducted before the camshaft is suspected of failure. Once these items have been ruled out, the camshaft valve cover will be removed, and the camshaft will be directly inspected, or the lift of the rocker arms will be checked with a dial indicator. Once tested, it will be obvious that the camshaft lobe is no longer lifting the cylinder head valve enough to allow for proper operation.

For engines with the camshaft mounted internally in the engine block, either the engine will require removal, partial removal, or many components will be removed to gain adequate clearance to slide the camshaft out of the front of the engine, check the status of the camshaft bearings, and instal new components. Engines with overhead cams will require removal of the timing covers, timing adjusters, timing belt or chain, valve covers, camshaft bearing caps or girdle, and any other obstructing components. Then camshaft can be lifted out, and the bearings will be inspected, measured, and replaced if possible to ensure the new camshaft will have proper support. Finally, camshaft bearing caps or girdle will be installed with new fasteners, and the engine can be reassembled. For pushrod type engines, the pushrods and lifters must be accessed by removing the intake manifold in many cases. Also, for many engines, the rocker arms must be completely removed, and the rocker arm studs will likely be rebuilt prior to installation of the rocker arms.

Upgrading the camshaft is a common engine performance modification, so when the camshaft must be replaced, many people opt for a performance version instead of the factory version. We recommend proceeding with caution and consulting a professional concerning the size of replacement camshaft, implications on drivability, and overall performance that can be expected of different products. This will likely prevent an undesirable condition after the repair.

There are many steps to identifying a failed camshaft, and they must be followed in proper succession in order to rule out the common issues that are known to occur. However, just because a engine camshafts do not typically fail, they should not be ignored if all else proves to be in good working order. Also, note that many types of variable valve timing exist, and these are typically mounted to and adjust the position of the camshaft in relation to the engine crankshaft. This should be taken into account when the crankshaft position sensor failure OBD trouble code is stored in the powertrain or engine control module.

This job should be left to a professional. Not only does it require accurate measurements and knowledge of internal engine components and functionality, but the tooling required to properly measure camshaft clearances, lobe lift, and runout are costly. There is also a high chance of causing damage to the engine if performed incorrectly, and if the engine must be removed from the vehicle there is a chance of injury. This job should not be taken lightly, and if there is any level of doubt concerning completion of the task, consult a professional first.