Cleaning Instrument Gauge Glass

[bpossel]

I am planning on cleaning the glass on my gauges, but wanted to get all of your input before I do this.

From what I have read, you start with removing the tach (reach behind the tach from under the dash)
Next move to the center cluster (no need to disconnect the oil and temp lines if only pulling out far enough to remove the glass).  The center cluster can be accessed via the opening from the tach.
Next remove the speedometer.  I read that the AC can remain attached?

Is it that simple?  What are the do's and dont's for removing the glass and making sure not to break and/or scratch anything?  How do I pry off the chrome without bending it?

Thanks for your help!
Bob

bpossel
Memphis, TN.
1971 280SL
1997 E320

[hauser]

I wonder if this would be a good time to replace the bulbs while doing this task?

1969 280sl 5 spd        1999 ML320          Gainesville,Fl.

[graphic66]

From memory you have the correct order. You may end up taking out the center cluster by unhooking the temp sending unit at the engine and the oil line at the gauge. If you do this attach a note to your keys to remind you to hook the oil line up before starting the engine, you may avoid an embarrasing mess. The glass comes off the speedo and tach the same on both. Lie them flat on thier faces and use a small screwdriver to pry the chrome lip slowly away from the back side of the bezel. You need to pry it up all the way around and the chrome piece will pull off from the front. The knobs through the glass will slide right off the shafts and to get them out of the glass you need to remove a small c-clip and washers. Work in a very clean area with very clean hands when doing this. The faces of the instruments can be cleaned with soft white cotton cloth and windex very gently. Upon reassembly you need to rebend the chrome, this will not be perfect and I have very gently pounded it back into shape with a drift while on a flat smooth surface with a pad under the gauge. Some things you may want to replace are the instrument illumination bulbs and the gaskets behind the instruments between the dash and the gauge, hey whats another fifty bucks at this point. The gauges have different mounting brackets on the backs so keep track of them and mind your brown ground wires at the back of the gauges. Remember to test the lights before reassembly by grounding them with the bulbs in and the center cluster plugged in. You may need to clean the rheostat on the cluster to get the dash lights to dim properly. Also apply dielectric silicone compound to the  sockets of the bulbs and the rheostat to insure a nice long corrosion free life. It's also a great time to hook up your headlight flasher in the stalk at the fusebox if it isn't already done. The center cluster glass comes off a little easier and will require less prying, the rheostat knob will just slide right off the shaft with the glass. Part numbers for the speedo and tach underlay gaskets are 100-542-0038, you will need 2, one for the tach and one for the speedo, part number for the instrument cluster underlay is 100-542-0138 you will need one. these will probably need to be replaced if they are cracked and broken. They go inbetween the gauges and the dash.

[Cees Klumper]

Just one quick addition - to bend the chrome back on, I used pliers with a piece of cloth (to prevent marring the chrome), rather than hitting it with a drift. From the back you can see it has been opened, from the front nothing is visible.

Cees Klumper in Amsterdam
'69 white 280 SL automatic