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+--- Thread: W123/W116/W126 OM617 Afterglow mod (/showthread.php?tid=335)
W123/W116/W126 OM617 Afterglow mod - ForcedInduction - 04-27-2009
Version 2: http://www.superturbodiesel.com/std/w123-w116-w126-om617-afterglow-mod-t-335.html#pid6058
This mod is easy and should take about an hour to finish. It makes quite a difference in cold idle quality, especially if your engine is worn.
The diagram is simple. You're splicing a relay into the violet wire of the glowplug relay's small plug. The start signal provides power for the relay to actuate when the relay is given a ground path through the 40*c coolant switch.
I used the existing relays and cannibalized the second relay base for its smaller gauge wires. These relays are common in the junkyard and the holder in the engine bay has plenty of spots to add another if you have working A/C. I desoldered the wire out of one pin and jumped the connection from the signal pin to the switched pin. Middle right goes back to the GP relay and top right is ground.
My HVAC is eliminated and the 40*c switch was unused so I cannibalized the connector but you can Y the existing wire without affecting blower operation.
Wiring can be made much shorter if you choose to install an aftermarket relay closer to the glowplug relay.
Good luck!
RE: W123/W116/W126 OM617 Afterglow mod - winmutt - 04-27-2009
What kind of soldering gun did you use? The one I have doesnt melt the MB solder. What relay was used?
RE: W123/W116/W126 OM617 Afterglow mod - ForcedInduction - 04-27-2009
It is a generic pistol-type electric soldering gun, no idea what brand or wattage. It was something I salvaged from the shop trash years ago. It also worked soldering the 4-brake light mod wires.
It looks something like this:
![[Image: 14319_300.jpg]](http://www.drillspot.com/pimages/143/14319_300.jpg)
I'm not sure which relay I used, neither was operating since the A/C had no pressure. I did check to see if it works and it does turn off the glowplugs when provided a ground through the switch.
RE: W123/W116/W126 OM617 Afterglow mod - tomnik - 04-27-2009
Don't you fear extended wear of the GPs?
40degC takes some time.
The newer models (W201, W124) and VWs have the afterglow as standard.
It is a common upgrade for veggie conversions.
I believe the glow time depends on coolant temps with variable time.
Also there are special GPs capable to afterglow, standard will die soon.
Original afterglow relays are very expensive.
Great job anyway,
Tom
RE: W123/W116/W126 OM617 Afterglow mod - ForcedInduction - 04-27-2009
(04-27-2009, 01:04 PM)tomnik Don't you fear extended wear of the GPs?Not in the least. I get junkyard Bosch glowplugs for free (or close to it if the desk guy is a dick) and it takes 10 minutes to diagnose and replace one.
RE: W123/W116/W126 OM617 Afterglow mod - kamel - 04-28-2009
I have thought of doing this mod as well, but I guess I never got to it. I also NEED to upgrade to the pencil type on mine, or just upgrade the whole motor when it finally lets go.
RE: W123/W116/W126 OM617 Afterglow mod - winmutt - 04-28-2009
(04-27-2009, 01:04 PM)tomnik Don't you fear extended wear of the GPs?
40degC takes some time.
The newer models (W201, W124) and VWs have the afterglow as standard.
It is a common upgrade for veggie conversions.
I believe the glow time depends on coolant temps with variable time.
Also there are special GPs capable to afterglow, standard will die soon.
Original afterglow relays are very expensive.
Great job anyway,
Tom
I've had mine for about 6 mos without the violet wire without issue.
RE: W123/W116/W126 OM617 Afterglow mod - Einar - 05-02-2009
I thought the usual way was to just cut the violet wire, then the relay would glow longer but stop glowing after a while.
This wears out GP faster and use much power from the battery/alternator.
Would`nt it be a better improvement to use a glow relay from a OM605 that have afterglow, just to change some of the connectors and it will work as on a OM605, and not glow for so long and "eat" up the GP`s
RE: W123/W116/W126 OM617 Afterglow mod - ForcedInduction - 05-02-2009
This mod does the same thing using existing hardware and some wire.
RE: W123/W116/W126 OM617 Afterglow mod - ForcedInduction - 09-02-2009
New mod.
This will make the glowplug light display any time the glowplugs are on, allow the glowplug timer to be canceled and allow the glowplugs to be manually turned on when the driver feels the need.
The second point, and my main reason for this mod, is very handy if you need to turn on the key without starting the engine or if you have installed a valve in the shutoff vacuum line to keep the engine running without the key.
Remove the relay.
Remove the 4 screws holding to body in the shell.
With the relay sitting on its top, the 4th pin from the bottom left is for the dash light.
Scratch or melt away the solder path going to the transistor leg to the upper right (circled).
Make a wire about 3" long.
Attach it to the hold-down screw on the output side of the main relay (pictured).
Run the wire under the board and solder it to the 4th pin.
Reassemble and reinstall to the car.
At this point the light mod is done. The next steps will allow manual control of glow and afterglow time.
Trace the violet wire from the relay to under the dash.
Snip it at a convenient point before it connects with the starter circuit.
Install a momentary push-on switch where you like.
Find a switched power source (I use the Black/Red wire from the cruise control module plug).
Wire the power source through the switch to the violet wire and you're done.
Optional: A diode can be installed between the switch and starter circuit if you want the glowplugs to cut out when the starter is used (no afterglow).
RE: W123/W116/W126 OM617 Afterglow mod - ForcedInduction - 06-26-2010
Bump to the top for cjbrown.
RE: W123/W116/W126 OM617 Afterglow mod - Captain America - 06-29-2010
Well I thought I posted this question last night but I must have been dreaming...
Is there a somewhat easy way to control the GP's....
On: Normal Operation
Off: Never turn on
On: Normal Operation with Afterglow
?
RE: W123/W116/W126 OM617 Afterglow mod - ForcedInduction - 06-29-2010
(06-29-2010, 10:01 AM)Captain America Is there a somewhat easy way to control the GP's....
On: Normal Operation
Off: Never turn on
On: Normal Operation with Afterglow
Yes. The first mod. Use a SPDT toggle with common connected to the GP relay, one leg connected to the thermoswitch and the other leg directly grounded.
RE: W123/W116/W126 OM617 Afterglow mod - Captain America - 06-29-2010
With it wired as you say will the GP light turn on whenever the GP's are on? no right?
RE: W123/W116/W126 OM617 Afterglow mod - ForcedInduction - 06-29-2010
The second modification will.
RE: W123/W116/W126 OM617 Afterglow mod - Captain America - 06-30-2010
Ok, So if I knew the function of the wire (s) and what controlled the glow plugs (turning them on and off) I wouldn't have to ask these dumb questions and I could easily figure this out in my sleep. Trying to guess what does what isn't working out so great and searching around has not turned up any results. So I apologize for that.
So I drew up the first sketch just thinkin
Then I drew up the second after I read your post Forced...
Which, if any is correct?
RE: W123/W116/W126 OM617 Afterglow mod - Captain America - 07-02-2010
I decided to do the GP light mod so I know exactly when the GP's are on an when they are off. I'm posting this because the inside of my GP relay is significantly different looking than FI's. I dunno why but his looks like it was made at home by a DIY guy and mine looks more like it came from a factory. The solder points are slightly different but I had no trouble figuring it out by following his instruction.
Took a sec to sand down the relay contacts
It turned out pretty nice and it works great!
RE: W123/W116/W126 OM617 Afterglow mod - nrkmann - 07-05-2010
Why not buy the Beru control unit and glow plugs for under $200. It does after glow and will also turn the glow plugs back on to improve emissions in very cold weather...
nrk
1986 300SDL
1964 230SL
RE: W123/W116/W126 OM617 Afterglow mod - willbhere4u - 07-05-2010
because this is free!
RE: W123/W116/W126 OM617 Afterglow mod - Captain America - 07-05-2010
Yup! Willbhere4u got it, and it works nice!
RE: W123/W116/W126 OM617 Afterglow mod - rdirtycar - 07-08-2010
(04-27-2009, 09:25 AM)ForcedInduction It is a generic pistol-type electric soldering gun, no idea what brand or wattage. It was something I salvaged from the shop trash years ago. It also worked soldering the 4-brake light mod wires.
It looks something like this:
I'm not sure which relay I used, neither was operating since the A/C had no pressure. I did check to see if it works and it does turn off the glowplugs when provided a ground through the switch.
I did go out and buy a really nice soldering gun from a HAM radio operators mail order catalog. Weller makes a huge version of their two wattage pistol soldering gun. The low on the larger is like the high on the smaller. It's a good solid soldering iron.
RE: W123/W116/W126 OM617 Afterglow mod - ForcedInduction - 07-10-2010
(07-02-2010, 10:41 AM)Captain America I dunno why but his looks like it was made at home by a DIY guy and mine looks more like it came from a factory.
Mine is the factory original from 1982, yours is probably a later model or different manufacturer.
RE: W123/W116/W126 OM617 Afterglow mod - Captain America - 07-11-2010
Ahhh, It must be a later model then... You can see VDO on the circuit board.