First of all I''d like to thank all who posted,,, a wealth of good information that has saved me money and preventing me form doing harm to my 87 300 SDL.
That said I would like to know if there are any tips or cautions that I may run into next weekend.
replace headlight switch,, low beams do not have 12 V,, fuse ok right beam sometimes work and then not,, high beams ok dash lite for ng light ok.
Ignition switch,, contacts getting funky,,
Thermostat Eng. temp. never gets above 60 C,, unless it's 100 F outside and driving up hill .
Thank you in advance,, Cheers
ps I have the parts, but not sure if they are OEM.

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Just remember the ignition and light switches receive non-fused supply directly from the battery. Be sure to disconnect the battery before doing anything to either of these devices.

But before you replace the switches make sure your fuses are good and making good contact. Order all new ceramic and copper fuses from pelican and re-fuse the whole box first. These fuses are notorious for looking good but being intermittent.

If your fuse clips look corroded clean them with non-abrasive metal polish.

Low temperature, classic case of stuck thermostat.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

will order copper fuses,, and I did verify the tabs,,, and good tip on the thermostat,, ,,,ty:} Ill keep the old one when I make a trip to the USA,, up here in Canada overheating is never a problem,,and I put her away for the winter due to the salt. The body is mint for Ontario,, I can fix just about anything but can not fight RUST.
I was debating about leaving the battery connected because the clock is funny,,, it takes about 50 tries ,,of time adjusts, before it works thats why I will never do the daylight savings thing,,,, is there a pin hole press and push release,, on the light switch knob,, to release it from the switch post ?
I have rebuilt 200 engines over 30 years but I cuss the dash and electrical work,, always breaking some tiny plastic thing,,,of which you can never find a replacement at the parts shop ,,,

The light switch Knob will just pull off the serrated post.Look and see if there's
a Tiny little light bulb in the center of the post under the knob,It's for your Fog
Lamps notification.('Tells you if they're turned on.)
[Pictogram is of the W124 Light switch,the W126 is same.]

Get Only, a Genuine Mercedes Thermostat of the correct temperature range for
your engine AND TEST IT IN A POT OF Hot Water on the Stove for proper opening temps.

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'84 300SD sold
124.128

You may need to (carefully) use pliers to pull the knob off of the light switch. It takes a fairly strong pull but it will eventually pull off. Make sure you're pulling straight out and no, there is not any kind of locking mechanism. Heed the advice about disconnecting the battery. Your clock problem may be that it needs new capacitors.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

I pull the knob with a pair of pliers too, but cover the knob with a rag so the pliers don`t ding the plastic.


Charlie

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

Thank you for the tips,, I was not aware of the light in the switch, had the car 2 years and it never worked !!!! good time to fix it,,, :] will take the thermostat in to work,, we have lab and calibration rooms next to my area emissions dept,,nice diagram,,, with out that I am working in the dark fiddle to fit and such ,,Cheers !!!
Hope the ignition switch is the same as the light switch,,once I had to remove the wood trim and it cracked, under the the clear coat,,,

Dave,

To operate the fog lamps the Headlight switch MUST be in either:
The Parking lights On (1st "Click" of the switch handle to the Right)
or
The Full Headlamps ON (2nd "Click" of the switch handle to the Right)

THEN
Pull the Switch Handle OUT (Towards You) 1 Click to get the front Fog Lamps.
Pull the Switch Handle OUT (Towards You) to the SECOND "Click" for Both Front and Rear Fogs.

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'84 300SD sold
124.128

Now both low beams not working,,, uhmmm is there a relay after the fuse box? high low beam switch on steering column appears to be working,,, ??? if I can not find the issue I may have to run new wires from the fuse box fuse 4 and 12 ,, low beam fuses,,, which is hot, to the connector at the low beam socket, with 8 amp fuse ,, inline,,,the head light switch will still turn low beams on / off at the fuse point,, re as per volt meter,,,if I put the new wires in,,, had the fuse box pulled up to inspect the wires under the number 4 and 12 fuse and they appear normal,,, note high and low share a common ground at the bulb connector,, running out of options tis easier to rebuild the engine vs fixing wiring issues aghghghg cuss cuss !!!!

While I was moving the fuse panel the lights went on,, only rh side,,, wiggle and jiggle and tap ,,,, very scientific I came to the conclusion that it may have something to do with the relays ,, not having a book I was just guessing what the long big one was for, it was much more sensitive to the tap and wiggle method. So on to the puter and price one by part number and it was $255 :{{{{ Only in Canada eh ?? So off to the auto wreckers and found a 89 300 gasser, The part numbers were the same so popped all the relays, and took them 6 of them home with me for $40 ,,,Now I have lights !!!

[QUOTE=Dave Donaldson;3037411]While I was moving the fuse panel the lights went on,, only rh side,,, wiggle and jiggle and tap ,,,, very scientific I came to the conclusion that it may have something to do with the relays ,, not having a book I was just guessing what the long big one was for, it was much more sensitive to the tap and wiggle method. So on to the puter and price one by part number and it was $255 :{{{{ Only in Canada eh ?? So off to the auto wreckers and found a 89 300 gasser, The part numbers were the same so popped all the relays, and took them 6 of them home with me for $40 ,,,Now I have lights !!![/QUOTE

It was probably the long light control relay. Black plastic cover. My rt fog light is intermittent after a few months of driving. I unplug the LKM and plug it back in and all is right with the world. Probably corroded terminals. Every time I see one in a junkyard I pull it for future use. They are expensive brand new.

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John
1986 300sdl
1985 380se