How To Set Valve Lash On A 6.6 Duramax Diesel Engine

Summary

This video tutorial guides viewers through setting the valves on an LB7 engine. It emphasizes the importance of setting the valve lash to 12 thou-inch and provides a clear explanation of how to identify the correct valve positions for adjustment. The presenter advises turning the engine over freely while replacing injectors and demonstrates how to set valves on even and odd-numbered cylinders. The video also covers the consequences of improper valve clearance, such as engine noise and power loss, and offers a practical tip for ensuring accuracy by using a feeler gauge. The tutorial is part of a series on diesel engine maintenance, including injector replacement and reassembling valve covers.

Takeaways

• 🔧 Adjusting valve lash on an LB7 engine is crucial for proper engine performance.
• ⚙️ The recommended valve lash setting is 12 thou (0.0012 inches) for this specific engine.
• 🎵 Turning the engine over freely is essential during injector replacement to avoid compression.
• 👷‍♂️ It's advisable to work alone or ensure no distractions when setting valves to avoid mistakes.
• 🔄 The engine can be set in two positions: when valves are rocking and when they are at top dead center (TDC).
• 🔢 Even-numbered valves are on the driver's side, while odd-numbered valves are on the passenger side.
• 🔩 The exhaust valve is longer and connects to the exhaust manifold, while the intake valve is shorter.
• 📊 Correct valve clearance is critical; too much clearance can lead to noise and reduced engine power.
• 📱 Using a diagram or reference during the process can help ensure accuracy and prevent mistakes.
• 🛠️ It's important to check and adjust valve clearance as engine components expand with heat.

Q & A

What is the recommended valve lash setting for the LB7 engine?

The recommended valve lash setting for the LB7 engine is 12 thousandths of an inch (12 tau).

Why is it suggested to work alone when setting the valve lash?

It is suggested to work alone when setting the valve lash to minimize distractions, which can cause you to forget important steps in the process.

What is meant by 'valves rocking' in the context of this engine setup?

'Valves rocking' refers to the movement of both the intake and exhaust valves. When one valve is opening, the other is closing, indicating the engine is at top dead center for that cylinder.

How do you identify which cylinder is at top dead center?

You can identify which cylinder is at top dead center by checking if the intake valve is closed and the exhaust valve is moving. For example, if cylinder #4 is rocking, cylinder #1 is on compression.

Which valves can be set when cylinder #1 is at top dead center?

When cylinder #1 is at top dead center, you can set the intake and exhaust valves on cylinder #1, the intake on cylinders #3 and #5, and the exhaust on cylinder #7.

What should you do after rotating the engine 360 degrees?

After rotating the engine 360 degrees, you can set the intake on cylinders #2, #4, and #8, and the exhaust on cylinders #4 and #6. You can also set the exhaust on cylinders #3 and #5 and the intake on cylinder #7.

Why is it important to avoid excessive valve clearance?

Excessive valve clearance can cause a noisy engine and prevent the valves from fully opening, which can reduce engine power and efficiency.

What happens if the valve clearance becomes too tight?

If the valve clearance becomes too tight, the valves may not fully close, resulting in a significant drop in engine power.

Why is valve clearance necessary in this engine?

Valve clearance is necessary because the engine has solid lifters, and as components like valves, rockers, and pushrods expand when heated, the clearance compensates for this expansion.

What should you do if you’re unsure about your work during the valve adjustment process?

If you're unsure about your work, it's a good idea to videotape the process so you can review it later and confirm everything was done correctly.