When my glow plug relay went out a few months ago, the dealer wanted $270 for one! I ended up buying a used working unit from the PickNPull for $12.

If that didn't work, I'd probably get a new one either from Pelican or possibly Walt (He carries the newer Hella type ones that glow a lot longer).

Packman

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83 240D - 4 speed manual - Manilla Beige
189K miles, Tachometer mod, cool wooden shift knob from PeachParts, CocoMats, Original factory paint, manual windows, manual sunroof. Starting to add AudioWrap to this car too!

http://catalog.peachparts.com/item.wws?sku=W0133-1606169&itempk=76207&mfr=Bosch&weight=0.94

__________________
Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out.
Check here for compatibility, diagnostics, and availability!

(4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!)


82 300SD 145k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k

Thanks. But that is a Bosch part, not Hella.

My search was for my '84 300TD. On one Fastlane page, below the Bosch relay, was listed an optional Hella Preglow time-relay, Part# 1331607146, for $193.50
I'll let someone else figure out what's the difference.

Happy Motoring, Mark

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DrDKW

That approach seems to be a bit inconsistent with your "Happy Motoring" philosophy. Anyone buying a Hella relay and thinking they are getting an afterglow unit isn't going to be happy. Neither is their wallet.

There was no explanation on the page for the difference. Maybe the Bosch is made in Singapore, while the Hella is still made in Germany.
Maybe someone could call Phil for an explanation.
Meanwhile, as I mentioned, I already got spare glowplug relays at the Pick-N-Pull

Happy Motoring, Mark

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DrDKW

I thought only Bosch had an afterglow relay for the W123.

__________________
1985 300D cali 190K

http://mercedes.thatchermathias.com/mw300d.jpg

Is Hella better than Bosch?

I've got Bosch units in both my SD's, they are probably original. Seem to be working flawlessly (the one needed the terminals cleaned)

I've no complaints.

__________________
Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out.
Check here for compatibility, diagnostics, and availability!

(4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!)


82 300SD 145k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k

Sorry to bump an old thread, but I thought I'd post some photos of my fried Glow Plug Relay. Any ideas what would have caused this?







I've replaced all five plugs and will check the wiring harness to make sure my ground is good. Is there anything else I should check before dropping in a replacement relay?

Attached Thumbnails

     

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1982 300TD

Everything I know about cars I learned from PeachParts.

Man, there was some serious heat going on in there. strange the fuse wouldn`t have blown to protect it.

Possibly a component inside the relay failed, but not drawing enough current to blow the strip fuse.

You can pick up a used one from PNP for around $10 to see if it was the relay or something else causing the problem, before buying a new one. but I`ll put my money on something in the old relay causing the heat.

Charlie

__________________
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

that's what the relay will look like if it sticks on. the ampdraw is low enough to prevent fuse failure, but constant enough to build heat inside the relay and melt plastic, etc...

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Looks like poor contact of the fuse strip which results in local heating at the contact area which melted the plastic. If you have continuity in the coil and no shorts, cleaning the fuse contact and making sure the 2 fuse screws are tight it may work just fine

__________________
85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

I'd agree. Just a little resistance could cause quite a lot of heat with the amount of current being drawn. Make sure the relay contacts are clean too. Use rolling papers to their best effect, then clean the relay contacts.

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mjk

'84 300SD 119KMi (Liesl der Diesel)
'84 300D 326KMi when the oil left (former parts car)
'82 300SD 253KMi (new parts car)

I cannot get my preheating to work, no light at the dash, no heat either.

I remember that just before the preheating light stops working, a strange sound like of short circuit was heard sometimes from the inside the dash at the left close to the door.
It is possible the some other fuse or relay could be damaged than the glow plug relay instead and it is the one to blame instead of the glow plugs relay??

I any case, does anybody here know how to test a glow plug relay and cables to it with a multimeter?

That is ...

1) voltages in the female pins in cable coming from ignition when it is set on and when is set off?
2) voltages in the corresponding male pins in the relay when the cable is removed but the relay is connect to battery?
3) voltages at the relay male pins out for the glow plugs when the ignition is set on and when is set off?

BTW, when I test the continuity of current in the female pins cable from the glow plugs (negative attached to the negative battery) I get a lecture in my multimeter in all the pins between 1.5 and 1.8 (set at 200 ohms position on tester).
I read here
http://www.dieselgiant.com/glowplugrepair.htm
that these values must be below 1.
So from it, I conclude my glow plugs are bad but working yet, so these cannot be the issue with my problem.
That was why it always start with some difficulty at mornings, but not like now.

Ideas???


TNX

Does the dash pre-glow light come on with the "light check" function when you first turn the key? This is when all the lights in the instrument panel are supposed to light up as a bulb check. If not, then your bulb is dead.

If there are 12 volts at both ends of the strip fuse at the pre-glow relay, then your relay is _probably_ getting power.

Remove the fuse. Hold it in your hands, flex it a little. If it crumble or breaks, or if a crack becomes evident, the fuse must be replaced. It is an 80 amp strip fuse, not easy to find locally except maybe an MB dealership. Check with FLAPS, some do carry them, they certainly can order them.

If your multimeter is not a good, accurate meter, it will have a hard time measuring a resistance of less than 1 ohm. I wouldn't be to worried about those values if you have a cheapo-meter that cost less than $50 or was made in china. The resistance test is best used to find dead shorts (zero ohms) or blown plugs (infinite resistance). Very unusual for all the glow plugs to fail at once, so if the readings are consistent, they are probably good.

Beyond that, you'll need a wiring diagram to chase down all the wires and what each should measure.

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Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC