380 116 V-8 valve adjustment/check - PeachParts Mercedes-Benz Forum

gedeonbgjr · #1 06-15-2003, 06:08 PM

Hi,
I would like to know if there is any other way to check the valve adjustment (hlc preload) than using the MB special tool, (as I don't have one). I am rebuilding my 1983 116 V-8. The heads have just had new guides installed and valves reground and I would like to check the hyd. lifter adjustment before reassembly. Any help or suggestions would be appreciated.
Thanks,
Bob

stevebfl · #2 06-15-2003, 07:40 PM

Ya gotta get the tool.

I suppose one could make a tool if one had a tool to get the measurements from.

Let me explain what you are doing and maybe you can find a different way to do it.

With the rocker arm off, the the ball of the lifter extends all way. If one could measure the height of the top of the lifter from the surface of the head one would have a similar measurement.

Now put the rocker arm on and push the rocker to the bottom and release (actually we usually squeeze all the lifters in a vise before reassembly so that when the rocker is placed on the lifter it automatically depresses to the heigth that pushes the rocker against the cam. This is the measurement you are trying to establish. The tool sits on the head and the measuring pin drops through the hole in the rocker and measures the height from its base (the head) to the ball of the lifter. The tool has the increments on the side.

It is my impression that the lifter is supposed to be depressed maybe half of its possible travel. So if one can measure the height with no rocker and the height totally depressed (run the cam till the valve is down - if the lifter has been squeezed to remove the oil the lifter will compress when the valve is lifted). You now would have two extents of travel. Some where inbetween there is right.

ctaylor738 · #3 06-15-2003, 09:34 PM

Having been through this on my 380SL, I can only echo Steve B - ya gotta have the tool. MB is now reselling AST's tool. I paid $50 at the dealer - well worth it.

Ya gotta get a good adjustment because you have changed all the variables with your head and valve work.

gedeonbgjr · #4 06-15-2003, 09:54 PM

Thanks to both for the quick response and info very much appreciated. I will check the local dealer tomorrow for the tool. I am sure I will have many many more questions in the future during this rebuild. My engine manual is a little vague in explaining procedures.
Thanks again,
Bob

ctaylor738 · #5 06-15-2003, 10:35 PM

While you are at it, make sure you have at least four 5.1 mm valve pads. You will want to do at least one side at a time, and the 5.1 mm pads are useful to determine the pads you will buy to get the pre-load correct.

Here is a good post on the subject:

http://www.peachparts.com/shopforum/showthread.php?threadid=53926&highlight=hlc

Here is a quote about my technique:

"The guage gives an indication of the preload, but that measurement is relative to the thickness of the hockey puck. So if a correction is needed, the thickness of the hockey puck will need to be determined so that the appropriate thickness for correction can be obtained.

Hockey pucks (actually called valve pads or thrust washers) come in seven thicknesses in .35 mm increments with 5.1 mm as the mid point.

Example. The guage shows an additional pre-load of ~.4 mm is needed. Remove the puck and "mike" it. It is a 4.75 size. Obtain a 5.1 puck to correct.

Be aware that the pucks can be pitted badly where the rockers contact them and take this into account when determining the correct replacement thickness.

Also, once a HLC has been unloaded by removing the rocker, it can take some time to return. Wait at least 10 minutes to re-measure. Once I made the corrections on mine, I let it sit overnight and then remeasured and found one lobe where a thinner puck was more appropriate.

If you find you need to go below 4.4 or beyond 5.8 mm to correct, you should probably check that valve and HLC out closely. Herr Fuchs told me that he has only used one 6.15 puck ever.

Cheers."