i recently began driving my 80 240D again, and after dropping and cleaning the tank, replacing fuel hoses, etc., the car has run better than it ever has during my now five year ownership. i also replaced the fuel sending unit, fog lamps, and turn signals, all sourced from an 85 300D turbo. since then, the battery will not hold a charge.
i checked the voltage regulator and it was toast so i ordered up a new one (awesome turnaround time from fastlane, per usual) and put it on. now, the car runs fine for a nice drive of 20-30 miles (after spending the night on the trickle charge), then i'll shut it off and the next time i go to drive it, it either won't start at all or will go for a little bit and then after a few minutes into the trip the lights start dimming, the radio shuts off, the windshield wipers move very slowly. is it time to just admit defeat and go for a new alternator, or is it something else that could be the problem? i should mention that it did this every so often before the new lights/sending unit were put in.
The only hitch throughout the work i've done so far was with the sending unit, in that i unplugged the wiring for it and it sat like that for a while, as i was waiting for some free time to do the fuel system work all together. i drove the car with these wires loose, about 150-200 miles or so. while unplugging it, the plastic housing for the wires broke off. could this have any effect on what's happening now, or is that a non-issue? i plan on getting the alternator checked out tomorrow, but in the meantime, any help or suggestions would be greatly appreciated.

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1980 240D, 197580 miles - "The Stuttgart Stomper"

If you have a DVM, get the engine started and check Voltage across the battery. With engine running it should be somewhere in the area of about 13.5 to 14.5 Volts. If it is, then your charging system is working.

If the charging system is working, remove a battery cable and set up your DVM as an Ammeter and put in series with the battery cable and battery post. Your DVM should be good for at least 10 Amps to do this. With everything in the car turned off you should read something less than 50 milliAmps. If you are reading more than 50 milliAmps begin pulling fuses one at a time while watching the ammeter. When the current drops radically after removing a fuse, that is your offending circuit. The key will need to be on for this.

If the charging system is verified AND there is no appreciable current seen in the above paragraph procedure, have the battery tested.

Hope this helps.

X2 with Larry.
You can take his word as being on the money!!!!!
The testing with the DVM as an amp meter is done without the motor running.
Make sure all your earth straps are good & clean.
The connections in the plug in the back of the alt need to be tight & free of corrosion.
Good Luck.

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Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving

be sure and don't turn the key to the glow position when making this test. accessory only!

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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 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Good catch!

&/or have the car warm so it will start without glowing and disconnect the glow system. Start car & measure voltage output. I've had a bad glow timer stay on which pulled voltage down making it look like the alternator was not charging properly. You don't want to pull the alternator only to have it test good on a bench.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

It's actually the belt gemstones that's causing the problems. How can I remove the tensioner?

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1980 240D, 197580 miles - "The Stuttgart Stomper"

Tensioner*** not gemstones. Thanks again autocorrect.

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1980 240D, 197580 miles - "The Stuttgart Stomper"

two long bolts through the tensioner body.


one in the back that goes through a mounting bracket on the block

one near the adjusting nut that goes through the alt.

thank you!

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1980 240D, 197580 miles - "The Stuttgart Stomper"