How To Replace A Camshaft

Replacing a camshaft is a major engine repair that requires a high level of mechanical expertise. However, it is a job that can be completed at home with the right tools and knowledge. In this guide, we will walk you through the steps on how to replace a camshaft, from removing the old camshaft to installing the new one. We will also provide tips on how to troubleshoot common problems that may arise during the process.

Before you begin, it is important to gather all of the necessary tools and materials. You will need a new camshaft, camshaft bearings, camshaft seal, timing belt or chain, and a variety of wrenches, sockets, and screwdrivers. You will also need to have a Haynes or Chilton repair manual for your specific vehicle. Once you have all of the necessary tools and materials, you can begin the process of replacing the camshaft.

The first step is to remove the valve cover. Once the valve cover is removed, you will be able to access the camshaft. The next step is to remove the timing belt or chain. This will allow you to remove the camshaft. Once the camshaft is removed, you can inspect it for damage. If the camshaft is damaged, it will need to be replaced. If the camshaft is not damaged, you can reuse it. The next step is to install the new camshaft bearings. The camshaft bearings are responsible for supporting the camshaft and preventing it from moving. Once the camshaft bearings are installed, you can install the new camshaft. The next step is to install the timing belt or chain. Once the timing belt or chain is installed, you can install the valve cover.

Identifying the Need for Camshaft Replacement

The camshaft is a crucial component of an internal combustion engine that plays a vital role in regulating the timing and opening of the engine’s valves. Wear, damage, or misalignment of the camshaft can lead to a range of engine issues and reduced performance. Here’s a comprehensive guide to recognizing the common symptoms that may indicate the need for camshaft replacement.

Signs and Symptoms

Detecting a faulty camshaft requires close observation and analysis of the engine’s behavior. If you notice any of the following signs or symptoms, it’s advisable to consult with a qualified mechanic or perform further diagnostics to assess the camshaft’s condition.

Rough idling and stalling: A damaged or misaligned camshaft can disrupt the proper opening and closing of the valves, leading to irregular engine idling and stalling.
Reduced engine power: The camshaft’s role in valve timing directly affects the timing of the combustion cycle. A malfunctioning camshaft can cause reduced engine power and acceleration performance.
Unusual engine noises: Abnormal noises, such as ticking, tapping, or grinding sounds, may indicate wear or damage to the camshaft or its components.
Increased oil consumption: A damaged camshaft can cause increased oil consumption due to worn or leaking valve seals or damaged bearing surfaces.
Check engine light: In modern vehicles, a faulty camshaft can trigger the check engine light, indicating a potential issue with the engine’s valve timing system.

Symptom	Possible Cause
Rough idling and stalling	Damaged or misaligned camshaft
Reduced engine power	Malfunctioning camshaft affecting valve timing
Unusual engine noises (ticking, tapping, grinding)	Worn or damaged camshaft or components
Increased oil consumption	Damaged camshaft causing worn or leaking valve seals
Check engine light	Faulty camshaft triggering system malfunction

Selecting the Appropriate Camshaft

Choosing the right camshaft is critical for optimizing engine performance. The following factors should be considered when making your selection:

Valve Lift and Duration

Valve lift refers to the maximum amount that the valve opens, while duration is the period during which the valve remains open. Both lift and duration affect the flow of air and fuel into and out of the engine. Higher lift and longer duration increase air and fuel flow, but can also lead to decreased valve life and reduced low-end torque.

Advancing and Retarding the Camshaft Timing

Camshaft timing refers to the relationship between the position of the camshaft and the position of the crankshaft. Advancing the camshaft timing (moving it towards the front of the engine) increases valve overlap, resulting in more air and fuel flow at high RPM but reduced low-end torque. Retarding the camshaft timing (moving it towards the rear of the engine) decreases valve overlap, improving low-end torque but reducing high-end horsepower.

Factor	Effect
Valve Lift	Increases or decreases air and fuel flow
Valve Duration	Alters the period during which the valve remains open
Camshaft Timing	Adjusts the relationship between camshaft and crankshaft positions

Preparing the Engine for Camshaft Replacement

Before embarking on the camshaft replacement process, it is essential to prepare the engine thoroughly. This involves a series of steps to ensure the safety and efficiency of the job.

Step 1: Safety Precautions

* Disconnect the negative terminal of the battery to prevent electrical damage.
* Wear appropriate safety gear, such as gloves and safety glasses.
* Ensure adequate ventilation in the work area to avoid inhaling harmful fumes.

Step 2: Remove Engine Covers and Accessories

* Identify and remove the engine covers that provide access to the camshaft.
* Disconnect and remove any hoses, wires, or sensors that may interfere with the camshaft removal.

Step 3: Timing Chain or Belt Removal

The timing chain or belt is a crucial component that synchronizes the camshaft with the crankshaft. Removing it is essential to access the camshaft.

Procedure for Cam Timing Chain Removal:


a. Locate the timing chain tensioner.	b. Compress the tensioner using a special tool or wrench.
c. Remove the chain from the camshaft and crankshaft sprockets.	d. Inspect the chain for wear or damage. Replace if necessary.

Removing the Old Camshaft

1. Disconnect the negative battery terminal.

2. Remove the valve cover.

3. Rotate the crankshaft until the timing marks are aligned.

4. Remove the camshaft bolts.

– Note: The camshaft bolts are often torqued to a specific value. It is important to use a torque wrench to remove the bolts in order to avoid damaging the threads. The torque value for the camshaft bolts can be found in the vehicle’s service manual.

– Tip: If the camshaft bolts are seized, you can use a penetrating oil to help loosen them. Apply the penetrating oil to the bolts and let it sit for a few minutes before attempting to remove them.

Step	Action
1	Disconnect the negative battery terminal.
2	Remove the valve cover.
3	Rotate the crankshaft until the timing marks are aligned.
4	Remove the camshaft bolts.

5. Carefully lift the camshaft out of the engine.

Installing the New Camshaft

Once the head is removed and the old camshaft is out, you can install the new one. Before you do, though, you need to make sure that the timing marks on the camshaft and the crankshaft are aligned.

To do this, turn the crankshaft until the timing mark on the crankshaft pulley is aligned with the “0” mark on the timing cover. Then, turn the camshaft until the timing mark on the camshaft gear is aligned with the mark on the cylinder head.

Once the timing marks are aligned, you can install the new camshaft. To do this, first apply a thin layer of camshaft assembly lube to the camshaft journals and lobes. Then, carefully slide the camshaft into place.

Checking the Timing

Once the camshaft is installed, you need to check the timing to make sure that it is correct. To do this, turn the crankshaft two full revolutions and then check the timing marks again. The timing marks should still be aligned.

If the timing marks are not aligned, you need to adjust the timing belt or chain. To do this, loosen the tensioner and then turn the camshaft gear until the timing marks are aligned. Once the timing marks are aligned, tighten the tensioner.

Installing the Head

Once the timing is correct, you can install the head. To do this, first apply a thin layer of gasket sealant to the head gasket. Then, carefully place the head on the engine block.

Once the head is in place, you can tighten the head bolts. To do this, start by tightening the bolts in a crisscross pattern. Then, gradually tighten the bolts until they are all torqued to the specified value.

Installing the Valve Cover

Once the head bolts are tightened, you can install the valve cover. To do this, first apply a thin layer of gasket sealant to the valve cover gasket. Then, carefully place the valve cover on the head.

Once the valve cover is in place, you can tighten the valve cover bolts. To do this, start by tightening the bolts in a crisscross pattern. Then, gradually tighten the bolts until they are all torqued to the specified value.

Timing the Camshaft

Once the new camshaft is installed, it must be timed correctly to the crankshaft. This is a critical step that ensures the valves open and close at the correct time in relation to the piston’s movement.

To time the camshaft, first find the timing mark on the camshaft gear. This mark will usually be a small notch or dot. Next, find the corresponding timing mark on the crankshaft sprocket. This mark may be a different shape or color than the camshaft mark. Now, align the two marks so that they are directly opposite each other. This will ensure that the camshaft and crankshaft are in sync.

Once the marks are aligned, you can tighten the camshaft gear bolt. Be sure to torque the bolt to the specified value in the vehicle’s service manual. Once the bolt is tight, reassemble the timing belt or chain and tensioner.

Finally, double-check the camshaft timing to ensure it is correct. Rotate the crankshaft two full revolutions and check that the camshaft timing marks are still aligned. This will verify that the camshaft is timed properly and that the engine will run correctly.

Troubleshooting Camshaft Timing

> Symptom	Possible Cause	Solution
Engine does not start	Camshaft is not timed correctly	Retime the camshaft according to the manufacturer’s specifications
Engine runs rough	Camshaft is slightly out of time	Adjust the camshaft timing slightly until the engine runs smoothly
Engine has no power	Camshaft is significantly out of time	Retime the camshaft according to the manufacturer’s specifications

Adjusting the Valve Lash

Adjusting the valve lash is a critical step in the camshaft replacement process. It ensures that the valves open and close at the correct time, allowing the engine to operate smoothly and efficiently. Here’s a detailed step-by-step guide on how to adjust the valve lash:

Locate the Valve Lash Adjusters: Identify the valve lash adjusters, which are typically located on top of the cylinder head. They are usually cylindrical or screw-shaped components.
Use a Feel-er Gauge: Insert a feel-er gauge (a thin, flat tool with various thickness measurements) between the rocker arm and the valve stem. The correct lash is specified in the vehicle’s service manual.
Adjust the Valve Lash Adjusters: Hold the feel-er gauge in place and adjust the valve lash adjusters using a wrench or special tool. Loosen the lock nut and turn the adjuster screw or nut until the feel-er gauge slides in with a slight drag.
Tighten the Lock Nut: Once the correct lash is achieved, tighten the lock nut securely to prevent the adjustment from changing.
Check All Valves: Repeat the process for all valves, ensuring that they have the correct lash.
Reassemble the Components: Reinstall the camshaft, rocker arms, and any other components removed during the lash adjustment process.
Verify Engine Operation: Start the engine and check for proper valve operation. Listen for any unusual noises or vibrations that may indicate incorrect valve lash adjustment.

Tool	Use
Feel-er Gauge	Measuring valve lash
Wrench or Special Tool	Adjusting valve lash adjusters
Service Manual	Determining correct valve lash specifications

Reassembling the Engine

Step 8: Installing the Camshaft and Timing Components

This is a crucial step that requires meticulous attention to detail. The following sub-steps should be followed with precision:

Align the Timing Marks: Ensure that the timing marks on the camshaft gear and crankshaft sprocket align perfectly. This precise alignment is essential for proper engine timing.
Insert the Camshaft: Carefully slide the camshaft into its bearings in the cylinder head. Handle it with care to avoid any scratches or damage.
Install the Camshaft Gear: Place the camshaft gear onto the camshaft and secure it with the retaining bolt. Tighten the bolt to the specified torque using a torque wrench.
Install the Timing Chain or Belt: Loop the timing chain or belt around the camshaft gear, crankshaft sprocket, and any idler gears or sprockets involved. Ensure that the chain or belt is properly tensioned according to the vehicle’s specifications.
Check Timing: Manually rotate the crankshaft two full revolutions to check if the timing marks still align. This verifies that the timing components have been installed correctly and that the engine will operate properly.

Tool	Purpose
Torque wrench	Tightening the camshaft gear retaining bolt to the specified torque
Timing light	Verifying proper timing by checking the alignment of timing marks with an engine running
Feeler gauge	Adjusting the timing chain or belt tension to within specification

Starting and Running the Engine

Preparations Before Starting

Before starting the engine, ensure that all bolts and connections are tight and secure. Fill the engine with oil and coolant to the appropriate levels. Connect the battery and fuel lines.

Starting the Engine

1. Turn the ignition key to the “On” position without starting the engine. This will prime the fuel system and build up oil pressure.

2. Start the engine by turning the ignition key to the “Start” position.

Running the Engine

3. Let the engine idle for a few minutes to warm up.

4. Check for any unusual noises or leaks.

5. Adjust the idle speed to the manufacturer’s specifications using the idle adjustment screw.

6. Drive the vehicle at varying speeds to ensure that the engine is running smoothly and efficiently.

Monitoring and Troubleshooting

7. Use a scan tool or code reader to monitor engine performance and identify any potential issues.

8. Listen for any unusual noises or vibrations during driving.

9. Regularly check the oil and coolant levels to ensure that they are within the specified range. Use the table below to troubleshoot potential issues:

Symptom	Possible Cause
Engine misfires	Incorrect ignition timing, faulty spark plugs, or fuel injector issues
Engine stalls	Fuel pump failure, intake air leaks, or sensor malfunctions
Excessive oil consumption	Worn piston rings, valve guides, or crankshaft seals
Overheating	Coolant leaks, faulty thermostat, or water pump failure

Verifying Camshaft Performance

10. Inspecting Cam Lobe Wear

Carefully examine the cam lobes for any signs of wear, such as pitting, scoring, or discoloration. Uneven wear can indicate a problem with the camshaft, lifters, or valve train components. Use a micrometer to measure the cam lobe height and compare it to the manufacturer’s specifications. Excessive lobe wear may require replacing the camshaft and other affected components.

Table: Cam Lobe Wear Inspection

Parameter	Inspection Method
Cam Lobe Height	Micrometer Measurement
Pitting and Scoring	Visual Inspection
Discoloration	Visual Inspection

Additional Tips:

* Use a flashlight to illuminate the cam lobes for better visibility.
* Rotate the camshaft slowly to inspect all lobes thoroughly.
* Compare the wear pattern on the cam lobes to determine if it is uniform or localized.
* If significant wear is present, consult a qualified mechanic for further diagnosis and repair.