What is the recommended valve clearance?

There is no single universal value for valve clearance. The recommended clearance is engine-specific and must come from the manufacturer’s service data for your exact model and configuration. Always verify the exact specification with the official sources before attempting any adjustment.

Understanding what valve clearance is and why it matters

Valve clearance, or lash, is the small gap between a valve stem and its rocker or cam follower. This gap accounts for thermal expansion, lubrication, and mechanical wear so the valve opens and closes properly. If the clearance is too tight, valves may not fully close, causing heat and wear; if it’s too loose, you can get noisy operation and reduced performance. Many modern engines use hydraulic lifters to automatically compensate for small changes, but some engines still require manual clearance adjustments.

Where to find the exact specification for your engine

To ensure accuracy, use official, model-specific sources. The following are reliable pathways to obtain the exact valve clearance specification for your engine:

• The factory service manual for your exact year, make, and model (including trim level and engine code).


• Official manufacturer service information portals or dealership service bulletins that publish maintenance data for your engine.


• Authorized repair facilities or qualified technicians who have access to VIN-specific service data.


• Reputable automotive repair manuals that cite the manufacturer specifications and note any model-specific exceptions.

In all cases, confirm the spec for your exact engine configuration and follow the procedure described in your manual. If the data cannot be located, do not guess or improvise; consult a dealer or specialist.

How valve clearance is typically specified and measured (general guidance)

Measurements are usually made when the engine is at a specified temperature (cold is common unless the manual specifies hot), using a precise feeler gauge in the correct units (usually millimeters or inches). The method and tolerance vary by engine design (overhead cam, pushrod, hydraulic lifters, etc.), so always follow the exact steps in the manufacturer’s procedure.

1. Prepare the engine by ensuring it is at the proper temperature state as specified (commonly cold). Disconnect the battery and follow all safety protocols.


2. Rotate the engine to the correct position (often Top Dead Center on the compression stroke for the target cylinder) as described in the service data.


3. Remove necessary components (such as valve covers or cam covers) to access the valve lash points.


4. Measure the clearance with the appropriate feeler gauge and compare it to the specified range for that cylinder and valve (intake vs. exhaust, if separate specs exist).


5. If out of spec, adjust using the engine’s approved method (shim changes, adjusting screws, or lifter replacement) according to the manual.


6. Repeat measurements for all cylinders as required, then reassemble and test run the engine to verify proper operation and that clearances remain within spec.

Concluding: Accurate measurement and adjustment require following the exact procedure in the manufacturer’s manual. Temperature, instrument tolerance, and engine design all influence the final numbers and steps.

Common pitfalls and when to seek professional help

• Using an incorrect specification for your exact engine variant or misidentifying the engine code.


• Misreading the measurement due to incorrect cylinder position or wrong feeler gauge size.


• Ignoring the difference between cold and hot clearance if the manual specifies one state over the other.


• Attempting adjustments without the proper tools or without understanding whether the engine uses hydraulic lifters or solid lifters.

If you’re unsure or lack the proper tools and manuals, it is advisable to seek professional service. Valve clearance work is precise and mistakes can lead to valve train damage or poor engine performance.

Summary

The recommended valve clearance is engine-specific and must be taken from the manufacturer’s service data for your exact model. There is no one-size-fits-all figure. Locate the official spec from the factory manual or authorized service information, follow the exact measurement and adjustment procedures, and consult a professional if you’re uncertain. Maintaining correct lash helps ensure optimal performance, efficiency, and longevity of the engine.

What happens if the valve clearance is too big?

If valve clearance is too big, the engine will become noisy, performance will decrease, and components will experience excessive wear. The valve opens later and closes earlier than intended, shortening its duration and lift, which reduces efficiency and can lead to increased wear on the valve train.
 
Noise and wear

• Engine noise: A "ticking" or "clattering" noise is created as the parts of the valve train, like the tappets or rocker arms, make contact with excessive slack. 
• Increased wear: This excessive slack causes impact, leading to faster wear on components such as the tappets, rocker arms, and cam followers. 

Performance and efficiency

• Reduced performance: The engine will have less power because the valve doesn't open as far or as long, which creates less efficient combustion. 
• Decreased efficiency: On the intake stroke, a larger gap means the valve opens later and takes longer to open fully, which can lead to a less efficient mixture of air and fuel. 

Potential for more serious damage 

• Burnt valves: Although more common with too little clearance, excessive clearance can also lead to burnt valves by affecting the timing and combustion process, especially on exhaust valves which handle very high temperatures. 
• Component failure: In extreme cases, the excessive force or lack of proper valve timing can lead to more catastrophic failure. 

How to address excessive valve clearance

• Adjust the clearance: The proper solution is to adjust the valve clearance to the manufacturer's specifications.
• Check when cold: Always make sure the engine is cold before checking and adjusting valve clearances, as metal expands when it heats up. 

What is the rule for valve clearance?

The parts book states that the valve clearance should be 0.013” (13 thousands of an inch) both hot and cold. So, you adjust the valve clearance to 0.013”. If you work in the metric system, then this is 0.33mm.

Is more or less valve clearance better?

Ignoring valve adjustments can have dire consequences for your engine. Tight valve clearance can result in loss of compression, reduced power, and increased fuel consumption, while loose clearance can cause valve noise, poor idle quality, and even valve float, where the valves fail to close properly.

How do I know if my valves need to be adjusted?

You know your engine's valves may need adjustment if you hear a ticking or clattering noise from the engine, experience a loss of power, rough idling, or notice poor fuel efficiency. These symptoms can also include hard starting, misfires, or even blue smoke from the tailpipe, which can indicate that either too much or too little clearance is causing performance issues. 
Common signs that valves need adjustment 

• Noises: A common sign is a distinct "ticking" or "clattering" sound from the engine. This is often more noticeable when the engine is under load or at higher RPMs. 
• Loss of power: If your vehicle's acceleration feels sluggish, you may have improper valve clearance affecting performance. 
• Rough idling: Valves not closing properly can disrupt the airflow into the engine, leading to a rough or erratic idle. 
• Poor fuel efficiency: Incorrect valve clearance can negatively impact the engine's combustion process, leading to decreased fuel economy. 
• Difficulty starting: Valves that are too tight can make the engine harder to start, particularly on cold starts. 
• Misfires: Valves not sealing correctly can lead to engine misfires. 

What to do next

• Check the owner's manual: Your vehicle's manual will have a recommended schedule for valve inspections and adjustments. 
• Consult a professional: If you experience any of these symptoms, have a mechanic inspect the engine to determine if a valve adjustment is needed. A professional can use tools like a feeler gauge to accurately measure the valve clearance and perform the necessary adjustments.