For the last year, I've been commuting 50 miles each way to grad school. She's a '79 300td and has been dead-on reliable. It even started on the first try when it was -5 F in the dead of winter.

Since Monday, my driving habits have changed and I'm driving 14 miles each way to a new job. Now the car needs a jump to get started in the AM or after work. The battery light does not flicker at low idle either...

The battery, alt and belts are only 3 years old.

When I think about it, it did the same thing before my year of 100 miles/day of commuting. At that time, I assumed it was alternator- so replaced it. The belts and battery were done at the same time and were in need of replacement.

I wonder what's draining the battery? I don't think it's the alternator.

Here's a quick scenario. After work, car was dead. Co-worker gave me a jump and it popped over. Drove home parked in garage. An hour later, she started right up and I went to the gym. After leaving the gym 1.5 hrs later, it started. Drove 5 mins to get some food. Went in and came out 10 mins later. Car dead, so wife drove over and jumped- she popped over easily. I have the car on a charger overnight...

TIA for thoughts on this.

__________________
'07 Yukon 2500
'13 Subaru Outback 3.6R
'13 Orbea Carpe 9-speed

Currently Benzless
Formerly: 300TD, S600, E55, 560SEL

---= The forest breathes, listen.
-Native American elder

you're going to need a digital meter that reads DC current, and you will need to test a few things.
exact battery voltage before you attempt to start the car.
battery voltage as the motor is starting the car.
battery voltage as the motor is running at idle, and at a higher RPM level.

__________________
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!

What exactly is it doing? Nothing? Clicking? turning over slowly?

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

It'll turn slow a few times, then resort to clicking. The headlights (interior dome if door is open) will dim some (dim-sum!) , but nothing dramatic.

__________________
'07 Yukon 2500
'13 Subaru Outback 3.6R
'13 Orbea Carpe 9-speed

Currently Benzless
Formerly: 300TD, S600, E55, 560SEL

---= The forest breathes, listen.
-Native American elder

I'm with VStech. I replaced the alternator in my SD with an Autozone rebuilt. It lasted about a month. They replaced it for free, but the point is -- it only lasted a month. Generally I order quality parts from this site but I skirted away on that one because of shipping (both ways - rebuilt and core). Should have bitten the bullet and ordered anyway. As VStech says, get voltage readings and repost.

__________________
John Schroader
bio burnin' 83 300D, '83 300 SD, '79 240D
"I've never met a man who was good at making excuses who was good at anything else" Ben Franklin
"You cannot permanently help a man by doing for him what he could and should do for himself" Abraham Lincoln

I would check the ground straps and clean also.

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

have you tried leaving the earth lead off the battery over night & see if starts then. This would then suggest a slow drain.

__________________
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

I had the same problem in my '79 300CD. It turned out that the battery was not a sealed unit. I pried off the caps on the battery and it was say low on fluid. I put in some distilled water and all is now well.

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"Life is tough...it's even tougher if you're stupid." John Wayne


Dave
Pawleys Island, SC

'79 300CD

Thanks for the input so far.

It charged overnight and started fine this morning. Now it's sitting in the lot at work. We'll see if starts this afternoon.

__________________
'07 Yukon 2500
'13 Subaru Outback 3.6R
'13 Orbea Carpe 9-speed

Currently Benzless
Formerly: 300TD, S600, E55, 560SEL

---= The forest breathes, listen.
-Native American elder

Can you turn the alternator pully by hand? If so the alternator belt is too loose. Although it should normally squeel a little if so when taking off but not all do.

Also you should have popped one cable off the battery this morning when arriving at work. Not a good place to find you have a battery draining issue.

I was thinking the same thing re: the alt belt -- it was noisy the first AM of no-start. I'll check it.

I work in mental health, so co-workers are more than helpful. Not necessarily mechanical genuises however.

__________________
'07 Yukon 2500
'13 Subaru Outback 3.6R
'13 Orbea Carpe 9-speed

Currently Benzless
Formerly: 300TD, S600, E55, 560SEL

---= The forest breathes, listen.
-Native American elder

If you find you can rotate the alternator pully by hand. You should be unable to budge it using the cooling fins. Plus it is too cold out at the moment to adjust the belt tension.

Dressing the belts on their v sections with a bar of face soap will usually give the belts additional traction for a few days until you can get to adjusting them if required.

Started no prob after work. I'll check the alt belt this weekend though...

__________________
'07 Yukon 2500
'13 Subaru Outback 3.6R
'13 Orbea Carpe 9-speed

Currently Benzless
Formerly: 300TD, S600, E55, 560SEL

---= The forest breathes, listen.
-Native American elder

I just checked with a multimeter...

Cold battery prestart 12v

Low idle 11.5v

Higher revs 11.9-12v

I charge the battery every weekend and this gets me by without getting stuck in parking lot with no start.

Alt belt isn't slipping. What kind of alt should I buy?

__________________
'07 Yukon 2500
'13 Subaru Outback 3.6R
'13 Orbea Carpe 9-speed

Currently Benzless
Formerly: 300TD, S600, E55, 560SEL

---= The forest breathes, listen.
-Native American elder

I believe that your votalges are low. The battery should be well above 12v cold and well above 14v when reving the engine.

__________________
rene
1983 300D