how do I jump start a diesel!?

[TheBeast_88K5]

I took the batteries out of my F-250, now they're dead....
They sat for 2 weeks, in the garage.

What's the best way to jump start a diesel?

 

[4X4HIGH]

I took the batteries out of my F-250, now they're dead....
They sat for 2 weeks, in the garage.

What's the best way to jump a diesel?

Probably with jumper cables.

 

[TheBeast_88K5]

I did that, but not much happened.
Do I need to jump both batteries at the same time?

 

[thelynx]

Same way you would jump start anything else + to + - to -, don’t worry about the second battery as they are wired in parallel.

If your cables and connections are good and you still have nothing its likely an open in the starter.

 

[NorCal_Chris]

you may have to double jump it lol.

 

[TheBeast_88K5]

I think the melted starter wire, miiiight have something to do with it....

 

[NorCal_Chris]

oh mike.....


i am so not suprised.

 

[TheBeast_88K5]

Good.... Then you've learned...

 

[Fordum]

Here is what you need to know. They put two batteries in there in parallel, because one can often not deliver enough current to spin the motor.
As the load increases, the internal resistance in the battery is such that the output voltage drops.

The funny thing about a starter motor, is that it will try to do its required amount of work.
For instance, say it takes 4800 watts of work to spin a motor. Watts is Volts times Amps.
If you supply that motor with 12 volts, it will draw 400 amps.
If you let the voltage drop to 6 volts, it will draw 800 amps.

When you try to jump it off with one battery, it cannot supply the amps needed at 12 volts. So, the voltage drops, the current goes up, until it reaches the max the battery can supply.
Which is enough to melt the starter wire.

The best way to jump it off?
Charge the batteries and put them back in.
Next best way?

A big battery, and really big jumper cables. Bigger than what you use to jump a car.

 

[kicker30]

If its a manual you might could roll it off and then let the batteries charge as it ran.

 

[bailey9r]

Plus if the batteries are dead they are soaking up a lot of what you are sending out

 

[DokWatson]

My Kia will jump start 1400CCA's worth of parallel batteries.....just takes 15-20 minutes

 

[DEMON44]

nope - when I jump big rigs that are dead you HAVE to hook up positive directly to the starter and ground to the frame somewhere close. that is the only way it will jump the engine, or as said, the dead batts will just eat up the current and the starter will never spin.

this is diesel field mechanic in cold climate learned. a tiger torch with a chunk of 4" stove pipe does wonders too.

 

[DrkZide]

*taking notes*

 

[DEMON44]

we got a battery cart with 2 8D batts on it for winter boosting in the yard in winter. and that feeds directly to the starter. sometimes a snort of ether. sometimes tigertorch on the pan to liquify the engine oil so it can actually turn over..... series 60 oil pans are...... fiberglass....... carefully heat it

 

[TheBeast_88K5]

Ugh... Diesel's.

 

[kicker30]

Ugh... Diesel's.

Funny thing about them, they take so much power to start, then unless it has an electric injection pump or something, it doesn't take any to run.

 

[thelynx]

nope - when I jump big rigs that are dead you HAVE to hook up positive directly to the starter and ground to the frame somewhere close. that is the only way it will jump the engine, or as said, the dead batts will just eat up the current and the starter will never spin.

this is diesel field mechanic in cold climate learned. a tiger torch with a chunk of 4" stove pipe does wonders too.

Good advise for cold starting. I am as well a Northern Field Mechanic working on CAT.

If you cant get to the starter or just dont feel like rolling in the dirt hook up your booster cables, run the boosting vehicle at a elivated idle and just sit back and relax for 20mins before attempting to start it.

There are all sorts of tricks for getting a diesel to start, some are better then others for both sucess and engine life

 

[diesel4me]

I'd say rolling it downhill and popping the clutch is one bad way to start a diesel truck--one reason is the high compression will put a big load on axle shafts & other driveline parts when you dump the clutch...another is an altenator trying to recharge TWO dead batteries will likely result in its demise..altenators anen't battery "chargers",they are battery "maintainers"...using one to fast charge a dead battery often overheats and destroys it..

When I jump my 6.2's I put the jumpers on the passenger side battery,the closest to the starter,less cable length for the current to flow thru the better--also it tends to increase the chances of getting more current to the starter since it wont have to flow thru the dead "second" battery on its way to the starter and possibly absorb all the amps that you want going to the starter..

 

[DokWatson]

Funny thing about them, they take so much power to start, then unless it has an electric injection pump or something, it doesn't take any to run.

Not quite. A lot of mechanical fuel injection systems needs 12v to the fuel cutoff solenoid.

Now, if it were to be converted to a manual or vacuum operated solenoid...it could work.