how to check pushrod length with hydraulic lifters

3 min read 05-02-2025

how to check pushrod length with hydraulic lifters

Checking pushrod length is crucial for proper engine valve train function. Incorrect pushrod length can lead to decreased performance, valve float, and even engine damage. This guide details how to accurately measure pushrod length on engines equipped with hydraulic lifters. Remember to consult your engine's service manual for specific instructions and torque specifications.

Understanding Hydraulic Lifters

Hydraulic lifters automatically adjust valve lash, eliminating the need for manual adjustments like with solid lifters. This self-adjusting mechanism simplifies the process, but accurate pushrod length is still essential for optimal performance. An improperly sized pushrod can interfere with the lifter's ability to adjust correctly.

Tools You'll Need

Before you begin, gather the necessary tools:

Pushrod length measuring tool: This specialized tool precisely measures pushrod length. A dial indicator can also be used for more precise measurements.
Feeler gauges: For checking valve lash (although not directly used for pushrod length measurement, this ensures accurate baseline readings before pushrod installation)
Torque wrench: To properly tighten components during reassembly.
Socket set: For removing and installing rocker arms, pushrods, and other components.
Clean rags: To prevent contamination.
Your engine's service manual: Crucial for torque specifications and detailed procedures.

Step-by-Step Guide to Checking Pushrod Length

These steps will guide you through the process:

1. Prepare the Engine

Consult your service manual: Familiarize yourself with the specific procedure for your engine.
Safety first: Disconnect the battery's negative terminal.
Access the valve train: Remove valve covers and any other necessary components to expose the rocker arms and pushrods.

2. Establish Baseline Valve Lash (Optional but Recommended)

Check valve lash: Before removing pushrods, use feeler gauges to measure the valve lash of each cylinder. This provides a baseline for comparison after pushrods are reinstalled, ensuring proper valve adjustment is maintained.

3. Remove the Pushrods

Carefully remove pushrods: One at a time, remove the pushrods. Keep them organized and labeled to avoid mixing them up. Note the cylinder each pushrod came from, as pushrods can sometimes vary slightly in length.

4. Measuring the Pushrods

Use a pushrod measuring tool: Insert the pushrod into the measuring tool. Note the exact length recorded. If you don't have a pushrod measuring tool, a more intricate method involves using a dial indicator and measuring the distance between the rocker arm and lifter surface with the valve fully closed. This is more complex and requires precision.
Document length: Write down the measured length for each pushrod, clearly identifying which cylinder it belongs to.

5. Compare to Specifications

Consult your engine's service manual: Your manual provides the correct pushrod length specification.
Analyze the measurements: Compare your measured lengths to the specifications. Any discrepancy requires further investigation.

6. Addressing Length Discrepancies

If pushrod lengths are incorrect:

Identify the cause: Check for bent or damaged pushrods. A worn lifter or rocker arm could also be the culprit. The cause needs to be identified and rectified before replacing pushrods.
Replace or adjust: Replace damaged pushrods or replace with the correct length. You may not need to replace if the length is slightly off, but consult your manual.

7. Reinstallation

Install new or corrected pushrods: Carefully install the pushrods in their respective locations.
Reinstall rocker arms: Securely install rocker arms, ensuring proper alignment.
Torque rocker arms: Tighten rocker arms according to the torque specifications in your service manual.
Re-check valve lash (if applicable): Re-check valve lash using feeler gauges to ensure proper adjustment after reinstallation.

8. Final Steps

Reassemble the engine: Carefully reinstall valve covers and other removed components.
Reconnect the battery: Reconnect the negative terminal of the battery.
Test the engine: Run the engine to ensure proper operation.

Troubleshooting

Incorrect valve lash: If you are experiencing issues after checking and adjusting pushrods, consider rechecking the valve lash as a common source of problems.
Bent pushrods: Bent pushrods are a frequent cause of incorrect pushrod length and will need to be replaced.
Worn components: Worn lifters or rocker arms can also lead to incorrect measurements, potentially requiring their replacement.

Conclusion

Checking pushrod length with hydraulic lifters is a critical step in maintaining your engine's performance. By carefully following these steps and consulting your service manual, you can ensure your engine runs smoothly and efficiently. Remember, accuracy is key, and if you're uncertain about any aspect of this procedure, seek professional assistance.