Hello,

I am trying to re-start a new-to-me 300D that I let sit for aprox two months. I kind of expected to have trouble, as it seems to have some kind of electrical drain that draws down the juice just enough to not let it crank up fast enough to restart. Last time I just brought out my spare battery, made sure it was re-charged, and jump-connected it while it sat on the ground. This worked fine the last time I tried it, but now I can't seem to get the engine to spin fast enough to start up. I tried the same battery jump thing this time and it still just weakly moans and barely turns over. I checked my connections and turned on my headlights to see how bright they were and these things checked out. I also brought out a voltmeter and measured the volts on the battery mounted in the car (11.91-V) and that of the jump-batter (12.18-V), so it seems like this would be enough to do the trick.

I worried that a might have done something bad however the first time a tried to connect the battery. I crossed my cables and accidentally, just for a second" touched the terminals with the cables crossed. This produced a big spark, but was only momentary. Could this have burned up something or killed something to the extent that it is not giving me this slow cranking symptom?

It's is cold out here, but only 49F, so it doesn't seem like coldness would be the issue?

Any ideas out there for me?

Thanks.

Most 12v batteries really put out 14.1V. You need the rest to make sure the starter spins fast enough.

Charge up a battery, make sure you have cleaned the poles and the insides of the cables, and hook it back up. Then use a car with the engine running to jump off the diesel.

Slow cranking is a low battery or a bad connection. Cleaning the terminals can eliminate the bad connection. If the engine turns slowly but then starts right up when it is jumped from a running car then your D car has a battery with a bad cell.

Charge up both of your batteries and take them to an Autozone and have them tested. If one of them has a shorted cell you will never get the car to start.

Crossing the poles and getting a big spark harmed nothing as long as you did not leave it hooked up that way.

Pooka

Thanks for the confirm on the the cross-cabled deal. I was really hoping I hadn't fried a computer or something.

I will now take ut the original batter and try to trickle chage it. Most other posts I've read however are from owners getting somewhere in the range of 12 volts if they measure with a voltmeter. They then get 13+ with engine running and alternator charging....

Thanks for the tips anyway. I'm not totally discouraged now...

The worst you could do is pop some diodes in the alternator by crossing the cables....

It should put out close to 14 vdc when you get it running.....

This would be measuring with dc voltmeter on the battery terminals with engine about 1000 rpm.........
Static battery volts with engine off should be between 12.5 & 13 with no load...This is just half of an alt test....

The alt may be suspect anyway....with the batteries that low you should see max alt output when you get it going......if not ...you may want to get the alt checked at a parts store......only way to measure (amp) output for sure...

A proper alt output tests checks both (VDC) & (max amps)....

__________________
1978 Yellow 300D (The Mustard Toad)
1980 Blue 240D (The Iron Toad)
1989 Grey Mitsu.4WD Mighty Max Pickup (Needs a Diesel transplant bad)

(Open the pod bay doors HAL)