Please tell me what this is.

[Delvis]

I have a couple of loose wires under the hood. Do any of them need to land on the water pump? Registered as 1970 280sl. Sorry for the lack of a good description. Need a little professional development. Please see picture.

Thanks in advance

Dev

[kampala]

If you are asking about the electrical connection on the Thermostat housing -- that is your 100 degree switch (there may be a more formal name for it).   If you still have a functioning stock (factory) ignition system for a later 280sl with transistorized ignition, two-way vacuum valve, stock distributor etc., then this switch triggers the system to advance the distributor at idle in order to raise the RPM a bit to help cool the car.   It triggers at 100 degrees celsius if I recall correctly.   

So the need depends on your set-up.   Many cars have this disconnected as they no longer have a fully functioning stock system. 

[Delvis]

Hi Kampala
Thank you for the quick reply. The car is new to me and I believe it still has a stock set-up. This past summer while stuck in traffic the car ran dangerously hot so I have been investigating potential causes. I will investigate under the hood further to see if I can locate all the original parts. I removed the battery today to locate the transistorized ignition box. I will now try to trace the correct wiring. I may send SOS in the next week or so if I run into road block. Thanks again!

DW

[Benz Dr.]

The main problem with the 100 C ( 212 F ) switch is I think it's set too high to actually do any good. Our cars normally run about 180 - 190 F and by the time you get it up to 212 or higher it's very close to being over heated. Advancing the ignition timing at idle speed will help but not enough to cool the engine all that much. What it might do is keep it from going any higher when what it really needs is to get some air flow under the car. That's often impossible if you're stuck in traffic. A 90 to 95 degree switch would be far more useful.

I had a 220Seb coupe once that had an auto trans. If I put it in a lower gear while in stop and go traffic it seemed to remove some of the load on the engine and it would idle a bit faster. Not that a 220 engine is prone to over heating like a late 280 but may help by increasing RPM as you move ahead in traffic.

 

[Delvis]

thanks Dr. Benz. comment/notes much appriciated.

[Delvis]

Hi Dan

does this look correct? this is the orphaned wire i located. I believe it fell off during shipping from previous owner to me.

PS:  you may or may not remeber this particular 280SL. It's a great 1970 White 280SL. the previous owner (Rod DeCourcy-Ireland)  had the joy of having you work/service this particular car from time to time. i have just been able to look though some old work summary (emails) authored by you. Any advice for this car would be welcomed greatly.

all the best

devlin

[Jonny B]

Here is a picture of the mounting of the 100C switch in my 280 SL. The wire connecting to it is pink with a grayish stripe.

[Delvis]

Thanks Jonny B

Much appreciated. I believe my wiring colours match. (From memory). I'll confirm this weekend when I visit the car (in off-site storage).

Many thanks.

DW

[Benz Dr.]

Rodd is a great guy. I did quite a bit of work on this car and it was in good shape when he sold it. Very solid higher number 3 car.

[Delvis]

Hi Dan. Great to know you have some finger prints on the car.  I agree with your assessment of Rodd and the car. Having fun getting to know the car and the great members of this w113 community. Happy new year and all the best for 2017 and beyond.

Cheers. DW

[Benz Dr.]

I can't remember now but I may of removed the 100 degree wire if the switch was going to ground. This will activate the vacuum control valve and make the distributor advance all of the time. You can test it by touching the wire to the terminal on the switch. There should be no difference in engine RPM under 100 degrees C or the switch is toast. Leave it unhooked if you see any change on a cold engine or replace the switch.

[Delvis]

thanks. Will investigate.

thank you for advise and direction.

cheers
DW