I'm having a problem getting my 300SD boosted after sitting all winter. When I turn the key it turns over as if there is very little current (i.e. dead battery). I tried boosting it straight to the battery cables instead of connecting to the battery, and the same thing, except the battery cables became so hot some of the plastic on them started melting......

Any ideas?

BTW, I'm boosting from my Dodge Ram 2500 diesel.....

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79 300SD - $50 out of pocket purchase
03 Dodge Ram 3500 CTD
2003 VW Jetta TDI

Sounds like a bad battery to me. I'd take it to an auto parts store and have it tested.

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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

I bypassed the battery completely.....

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79 300SD - $50 out of pocket purchase
03 Dodge Ram 3500 CTD
2003 VW Jetta TDI

You may want to temporarily install the good battery, you get better connections that way, I've seen it work. You may also want to replace the cables that got very hot.

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83 SD

84 CD

But if I bypassed the battery and went straight to the battery cables, shouldn't I have enough power from a running vehicle to start it?

Something else has to be wrong.

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79 300SD - $50 out of pocket purchase
03 Dodge Ram 3500 CTD
2003 VW Jetta TDI

Replace your battery. If that doesn't work it could be a burnt out starter solenoid. My car began giving me starting problems this winter, but once i replaced the battery (and primed my fuel system) I've had no more problems.

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1963 Ford F100 - Cummins Swap?
1985 Mercedes 300SD - 210K
1992 Ford Festiva - 92K
2001 Ninja 250 - 8K

Okay, fine....I can get a new battery.

But if boosting it from a running vehicle without a battery, i.e. STRAIGHT TO THE CABLES doesn't work, isn't that indicative of a different problem than the dead battery that isn't there?

I'm not trying to boost the battery, I'm trying to boost directly to the starter.

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79 300SD - $50 out of pocket purchase
03 Dodge Ram 3500 CTD
2003 VW Jetta TDI

Are your booster cables of the same size as the battery cables? If they are not, it is quite likely they cannot carry adequate load to energize the starter. This would account for why they started melting.

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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

I'd test the existing battery before replacing it.

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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

I can't explain why it won't work by bypassing the battery apart from the fact that booster cables are not designed to carry a full starting load. But when I've run into a similar situation in the past, replacing the battery solved it.

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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

I'm not kidding. A friend had a similar situation, I suggested "just try with that good battery"... see above.
If it does work, then get a new battery.
Good luck.

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83 SD

84 CD

Jumper cables, have 3 things agains them. Size of the cable, quality of the connection, and the length of the cable. These all reduce the available power.
It is unlikely that all of the cells in the battery are dead.
Hook up the bat in the car, hook up the cables and let it "charge" for 15-20 while the truck runs, and see if it will start.
Make sure all of the connections are clean

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83 300SD Dark Silver Dark brown inside

I agree. There are very few jumper cables that are of sufficient diameter and have sufficient clamping capability to start a diesel.

Most will simply "assist" the dead battery.

I've been in the situation of needing a jump on the SD and it's absolutely necessary to "charge" the weak battery for 15 minutes before attempting to start the engine.

The cables, by themselves, will never start the engine. The clamp has four points of contact to the post on the starter. No way that you're getting 250 amps though that setup.

I have a portable battery pack that will start my diesel with a completely dead battery, much easier than playing around with jumper cables (about $150 at the local McParts place).

How do you make a "good" connection with that pack?