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Rocker Removal and Replacement
 
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Pelican Technical Article:

Rocker Removal and Replacement

Steve Vernon

Time:

1 hour1 hr

Tab:

$0

Talent:

**

Tools:

22mm socket or wrench, 17mm socket, large adjustable wrench, 14mm bent valve adjustment wrench

Applicable Models:

Mercedes-Benz W123 (1977-85)

Parts Required:

Valve cover gasket

Hot Tip:

Clean everything well

Performance Gain:

Stop oil leaks from the valve cover

Complementary Modification:

Valve adjustment

Removing the rocker is necessary for many procedures on the W123; including replacing the head gasket, and even though the rockers are very stout they do wear out and break especially if the engine suffers from oil starvation or a valve comes in contact with a piston.

The rockers will come off with the bases, shafts and followers complete as two groups. In the four cylinder engines the front rocker works the front and rear two cylinders where as in the five cylinder engines the rear rocker assembly handles the rear three cylinders. This article will show you how to remove and replace the rockers.

Over the years your car may have been serviced by multiple people including previous owners and this can lead to parts replaced with different size fasteners and hardware. The sizes of the nuts and bolts we give may be different from what you have so be prepared with different size sockets and wrenches. If something is different on your vehicle please let us know and share your info to help other users. If you have any questions or comments or even a different procedure you would like to share please leave it below and please leave your vehicle information.

You will need to remove the valve covers to remove the rockers so please see our article on valve cover gasket replacement for additional step by step instructions.
Figure 1

You will need to remove the valve covers to remove the rockers so please see our article on valve cover gasket replacement for additional step by step instructions.

You are going to need to turn the motor until there is no pressure or contact between the valve and rocker.
Figure 2

You are going to need to turn the motor until there is no pressure or contact between the valve and rocker. Most people turn the motor from the nut on the crank but you can easily turn the motor form the nut on the end of the cam without causing any damage to the motor, just remember to turn the motor clockwise.

When you remove the valve cover there is a good chance that one of the valves will be under pressure by one of the cam lobes (red arrow) You will need to turn the motor until the front four lobes and valves are under no pressure like the number one cylinder (yellow arrows).
Figure 3

When you remove the valve cover there is a good chance that one of the valves will be under pressure by one of the cam lobes (red arrow) You will need to turn the motor until the front four lobes and valves are under no pressure like the number one cylinder (yellow arrows).

You can check that there is no pressure by grabbing the rocker and if it is not stressed it should wiggle in your hand just slightly.
Figure 4

You can check that there is no pressure by grabbing the rocker and if it is not stressed it should wiggle in your hand just slightly.

Use a 17mm socket and remove the two bolts holding the front assembly to the head.
Figure 5

Use a 17mm socket and remove the two bolts holding the front assembly to the head.

If you have positioned the cam correctly, the front assembly with the four rockers can easily be removed.
Figure 6

If you have positioned the cam correctly, the front assembly with the four rockers can easily be removed.

You want to perform the same procedures for the rear rocker assembly.
Figure 7

You want to perform the same procedures for the rear rocker assembly. It will be a little tighter of a fit getting the cam in a position where all rockers are un-stressed, especially if your valves are too tight. You may need to back off on one of the valves to get the clearance; to do this use a large adjustable wrench on the top of the spring seat (red arrow) to hold it from turning and then use your 14mm valve wrench (see valve adjustment article) to loosen the lower nut (yellow arrow) on the adjuster nuts.

If you have done this correctly the three cylinder assembly will come off of the head easily.
Figure 8

If you have done this correctly the three cylinder assembly will come off of the head easily.

While it is easy to remember which is which on the five cylinder engine it can be easy to mix them up on the four cylinder motors.
Figure 9

While it is easy to remember which is which on the five cylinder engine it can be easy to mix them up on the four cylinder motors. Take a cardboard box and insert the retaining bolts to hold the assemblies together and label them. It is a very good idea NOT to mix and match parts that have been rubbing together for a long time; keep the assemblies together.

Installation is the reverse or removal.
Figure 10

Installation is the reverse or removal. Make sure when you are installing the bases that the groove in the base sits in the protrusion on the head.

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