How to Adjust Car Valves (Part 2)

This post is a continuation of Part 1 on How to Adjust Car Valves. Lately, we have gone through the role of car valves.

We will now cover:

 – When to adjust the valves?

 – Step 1: Prepare your vehicle

– Step 2: Case 1: Check valve lash with an overhead camshaft

– Step 2: Case 2: Check the valve clearance using a screw and lock nut system

When to adjust the valves?

The adjustment of the valves is justified in different cases:

– Appearance of metallic noises during hot or cold operation, located in the camshaft area.

Good to know: precisely locate an engine noise using a large screwdriver applied to the suspect areas. The sound is amplified (stethoscope effect) by bringing the ear closer to the handle.

– Difficulty starting. Valves with insufficient clearance are “flanged.” They are not watertight when closed, which means that the engine lacks compression.

Good to know: an engine compression test can be carried out beforehand to validate the diagnosis.

Step1: Prepare your vehicle

– Identify the tuning system by obtaining the technical review dedicated to your car.

Good to know: the technical review allows you to know the technology used for your engine, its tuning method and the various preliminary operations for accessing the tuning.

– Work on a cold engine (unless otherwise specified by the manufacturer).

– Remove the upper engine crankcase (cylinder head or rocker covers).

– Lift the wheel on the front right side of the vehicle with a jack.

– Secure the workstation by adding a wheel chock.

Good to know: in the case of an engine coupled to an automatic transmission, you are obliged to drive the engine with a wrench through the crankshaft pulley’s nut.

Step 2: Case 1: Check valve lash with an overhead camshaft

This situation corresponds to a pellet setting.

The aim is to position the camshaft, which is visible, in such a way that the valve to be controlled is not constrained by it: the cam of the shaft must therefore point away from the tappet.

– Turn the engine by the wheel until the cam is correctly positioned.

– Using a set of shims, measure the clearance between the cam and the tappet. To do this, select the shim that slides without play but without forcing.

Good to know: you can add several shims to find the exact thickness, their gauge ranges from 0.04 mm to 1.20 mm.

– Repeat the process for all valves and note the value you find each time.

Step 2: Case 2: check the valve clearance using a screw and lock nut system

In this case, the camshaft is often not visually accessible. Engine positioning for each valve can be done in two ways (4-cylinder engine).

Use the so-called “balancing” method

This method allows the inlet and exhaust valve of the same cylinder to be adjusted simultaneously.

Turn the engine until the opposite cylinder’s valves are balanced: the exhaust valve will finish closing, and the intake valve will start opening.

– Check the valve clearance of the cylinder between the valve stem and the rocker arm.

◦ When cylinder 1 is in the balance position, check the intake and exhaust valves of cylinder 4.

◦ When cylinder 3 is in balance, check the valves of cylinder 2.

◦ When cylinder 4 is in balance, check the valves on cylinder 1.

◦ When Cylinder 2 is in balance, check the valves on Cylinder 3. 

Apply the “full opening” method

Another solution to bring the valves to the setpoint is the “full opening” method.

– Position each exhaust valve in turn to full opening (fully depressed by the cam).

– Check the corresponding valves.

◦ When the Cylinder 1 exhaust valve is set to fully open, check the Cylinder 3 intake valve’s clearance and the Cylinder 4 exhaust valve’s clearance.

◦ With Cylinder 3 exhaust valve in the fully open position, check the inlet valve’s clearance on Cylinder 4 and the clearance of the exhaust valve on Cylinder 2.

◦ With the cylinder 4 exhaust valve fully open, check the clearance of the cylinder 2 intake valve and the cylinder 1 exhaust valve’s clearance.

◦ With Cylinder 2 exhaust valve fully open, check the inlet valve’s clearance on Cylinder 1 and the clearance of the exhaust valve on Cylinder 3.

Good to know: These settings are valid for engines with ignition order 1-3-4-2.

This post will now continue in part 3 in our next publication. Stay posted, and remember to leave your comments below.

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