How to Adjust Tappet Clearance
In order to maintain smooth engine performance, it is essential to regularly check and adjust the tappet clearance of your vehicle. Tappets, also known as hydraulic lifters or valve lifters, play a crucial role in the proper functioning of the engine’s valvetrain. Incorrect tappet clearance can result in noisy operation, decreased power output, or even engine damage. Read on to learn the step-by-step procedure for adjusting tappet clearance.
Step 1: Gather the necessary tools
Before you begin, make sure you have the following tools:
1. A wrench or socket set
2. A feeler gauge set
3. A repair manual specific to your vehicle’s make and model
Step 2: Identify the tappet adjustment screws
Consult your repair manual to determine the location and number of tappets in your engine. In most cases, you’ll find them on the top of the engine, beneath the valve cover.
Step 3: Locate the top dead center (TDC) position
Refer to your repair manual to locate the TDC position for the specific cylinder you are adjusting. In general, this involves turning the crankshaft until the timing mark aligns with the designated pointer on the engine block.
Step 4: Loosen the lock nut
Using the appropriate wrench or socket, loosen the lock nut on the tappet adjustment screw. Be careful not to move the adjustment screw while doing so.
Step 5: Adjust the tappet clearance
Using a feeler gauge, slide the desired thickness gauge between the top of the valve stem and the tappet adjustment screw. You should feel slight resistance when it’s correctly in place.
Step 6: Tighten the lock nut
While holding the tappet adjustment screw, tighten the lock nut to the specified torque. Use a torque wrench if necessary, referring to your repair manual for the correct value.
Step 7: Recheck the tappet clearance
After tightening the lock nut, recheck the tappet clearance using the feeler gauge. If necessary, repeat steps 4-6 until the clearance is within the recommended tolerance.
Step 8: Repeat the process
Follow steps 4-7 for each tappet in your engine, ensuring that you adjust them all to the specified clearance value.
Step 9: Reinstall the valve cover
Once all tappet clearances have been adjusted, reinstall the valve cover using a torque wrench to tighten the bolts to the specified value.
By following these steps, you can successfully adjust the tappet clearance of your vehicle and enhance its overall performance. Remember to consult your vehicle’s repair manual for specific instructions and values, as they may vary among different makes and models.
20 Questions and Answers about How to Adjust Tappet Clearance:
1. What is tappet clearance?
Tappet clearance refers to the space between the top of a valve stem and the adjustment screw of a tappet in an engine.
2. Why is it important to adjust tappet clearance?
Properly adjusted tappet clearance ensures smooth engine operation, noise reduction, optimal power output, and improved fuel efficiency.
3. How often should tappet clearance be checked?
Tappet clearance should be checked and adjusted according to the manufacturer’s recommended maintenance schedule, typically every 20,000 to 30,000 miles or as specified in the repair manual.
4. What tools are required to adjust tappet clearance?
The tools needed include a wrench or socket set, a feeler gauge set, and a repair manual specific to your vehicle.
5. How can I determine the location of tappet adjustment screws in my engine?
Consult your vehicle’s repair manual for detailed information on the location and number of tappet adjustment screws.
6. What is the purpose of the top dead center (TDC) position?
Locating the TDC position is crucial for adjusting tappet clearance at the correct point in the engine’s rotation cycle.
7. How do I find the TDC position?
Refer to your vehicle’s repair manual for instructions on how to locate the TDC position accurately. This typically involves aligning timing marks on the crankshaft and engine block.
8. Can tappet clearance adjustment be done without loosening the lock nut?
No, loosening the lock nut is necessary to adjust the tappet clearance correctly.
9. How tight should the lock nut be tightened after adjusting the tappet clearance?
Refer to your vehicle’s repair manual for the recommended torque value for tightening the lock nut.
10. Can I use any thickness gauge for checking tappet clearance?
No, you should use a feeler gauge set that offers the specific thicknesses recommended by the manufacturer.
11. Is it necessary to recheck tappet clearance after tightening the lock nut?
Yes, it is important to recheck the tappet clearance to ensure it is within the specified tolerance range after tightening the lock nut.
12. What happens if tappet clearance is too tight?
If the tappet clearance is too tight, the valves may not fully close or may not open properly, leading to poor engine performance and potential valve damage.
13. What happens if tappet clearance is too loose?
If the tappet clearance is too loose, noisy valve operation and decreased power output may occur due to insufficient valve lift.
14. Can tappet clearance adjustment improve fuel efficiency?
Yes, adjusting tappet clearance to manufacturer specifications can optimize the engine’s performance, leading to improved fuel efficiency.
15. Can I adjust tappet clearance without a repair manual?
While it is possible to adjust tappet clearance without a repair manual, it is strongly recommended to consult one for accurate instructions and specifications for your specific vehicle.
16. Can improper tappet clearance cause engine damage?
Yes, incorrect tappet clearance can cause valve-related issues, such as burned valves, poor compression, or even valve-to-piston interference resulting in severe engine damage.
17. Can tappet clearance adjustment be done by a novice?
Although adjusting tappet clearance requires some mechanical knowledge and precision, a novice with the right tools and a repair manual can successfully perform the task.
18. Are tappet adjustments the same for all engines?
No, tappet adjustments vary among different engines, so it’s essential to follow the instructions in your specific vehicle’s repair manual.
19. Can I adjust tappet clearance if I have a hydraulic lifter engine?
Yes, even hydraulic lifter engines require occasional tappet clearance adjustments, although the process might differ from solid lifter engines.
20. Can I adjust tappet clearance on a vehicle with overhead camshafts?
Yes, tappet clearance adjustments can be made on vehicles with overhead camshafts, but the procedure may be more complex due to additional components and timing considerations.
