A good friend called with a "85"SD question. The GPs stay on for +- 2.5 minutes after the car starts and the alternator wont keep up with the draw resulting in a dead battery. his wife is running around doing errands in town and the battery will soon be dead with all the stopping and starting. The GPs shouldn't stay on for that long after the car starts, right?? Bad GP relay?

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

That definitely sound like a bad relay. Try to find a good used one just in case the problem is elsewhere.

I was having issues with my relay coming on and immediately clicking off. Instead of spending beaucoup $$$$ on the older style relay (which may not have been the problem), I said screw it and installed a Ford solenoid. It works great on my W123. My W126 still has a factory relay.

^^X2

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Current Stable

• 380SL (diesel)
• Corvette C5
• Manx
• Baja Bug
• F350 Powerstroke
• Auburn Boattail Speedster replica

Thanks guys. I have a used "85" 300TD (W123) GP relay, probably not usable for a test? It would be nice if we could verify the bad relay before he spends the bucks for a new one.

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

Unplug the relay. Probably don't need it that bad in NW Washington (if that means the state, not the district).

I would think that it would be compatible. I believe all the 82-85 cars used the same style relay. IIRC 001 545 98 32

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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 for the replies, It looks the same and when we swapped it in, it seemed to operate correctly, so I told him to order a new one from Peach Parts and gimmy my spare back

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

Something else is not right. 5 glow plugs once it reaches highest temp draws about 40 amps. The 85 SD has at least a 65 amp alternator and should keep up. Maybe it has a weak battery or weak alternator. If the glow plugs do indeed stay on for 2.5 minutes everytime the car is started and it is used for short trips then the battery may get weaker and weaker.

A solution is go manual. I have ones that are plug and play where the glow plugs are never on unless you push the button. Perfect for lot's of shot trips.

http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/359811-sale-manual-mercedes-glow-plug-controller-w123-300d-240d.html

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

When he installed my relay the GPs didn't stay on after the car started so we'l see what happens when he gets the new one. The alternator is new and the battery should be good, we'll see what happens.

I've had the manual push button, through a starter solenoid, system in my 79 240D for years, I love it, trouble fee, one less thing to go wrong. This SD is pretty nice and he wants to keep it OEM.

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"