so i took it for a short drive. when the lights and heat are on, it's in the upper 12's. when i rev the engine, it gets into the upper 13's. when lights and heat are off and i'm revving, it gets up to 14.11. maybe i'm ok? maybe i just need to drive it around a bit?

for the past two months, those two warning lights are dimly lit when i turn on the car. after i drive a bit, they turn off. i thought it might be related to battery/alternator.

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1980 300D, 128K

Make sure the belt is properly tensioned and not worn. You should not be able to make the belt slip on the pulley if turned by hand or with a tool. I have seen belts worn so bad they were riding on hte center section instead of the sides. Your voltages sound like the alt. is ok but maybe the belt is a bit loose. Make sure the battery connections at nice and clean too.

I use a small craftsman impact driver to get out screws like that, get a solid fitting bit, push in on the screw, and go. Comes loose every time. It has become extremely handy for tasks on the cars where there are screws that might strip if a normal screwdriver is used. Its like an impact gun for screws!

Another place I used it was disassembling things around the delivery valves on my om601 diesel...worked perfectly and fit into all the small spaces easier than a hand+screwdriver.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

Here we go again...

It had been working fine. I haven't driven it too much, but a few times. And now the battery is dead! Does that mean I need a new alternator?

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1980 300D, 128K

a few days ago, i checked the battery while idling (i don't think anything major was on, possibly the heat) and it was 14.38.

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1980 300D, 128K

It means there is a parasitic load.

Something is drawing power with key off = killing the battery.

The drain sounds random = possible relay sticking on..

.

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ASE Master Mechanic
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Technical Quality Auditor.
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1985 300SD
1983 300D
2003 Volvo V70

https://www.boldegoist.com/

that sounds difficult to diagnose!

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1980 300D, 128K