Hi,
I am a complete novice. My 1985 ex military Defender diesel, isnt starting.
I have ruled out the battery and the starter is getting 12v. It almost turns over but never really gets it done.
Any suggests on where I should look next?
Thank you for you help

 

Maybe corroded cables or a bad ground?

 

Here is a recording of what she sounds like when I try to start her.
Jump to :20

 

Would advise you start at the battery, clean those terminals. Follow the big cables from the battery. One should go to starter, remove and clean that up. One should go to frame ground, remove and clean that up. If you suspect your cables, you can connect a battery jumper cable set to bridge from (-) battery to metal frame. Starter draws like 300 amps, so does not take much corrosion to form a big voltage drop. A voltmeter connected from (+) battery to (+) on the starter should show voltage when cranking, but only like 1 volt drop, not five or six.

Could also be starter, but sounds like low volts to me.

 

The 300tdi starter can draw over 600 amps. I expect his could draw that much or close to it.
Yeah, make sure your cables all in good shape and well attached. All the large ones in the starter circuit, pos & neg.

 

Thank you everyone for all the help!
I was able to isolate the problem as a bad ground. When I grounded the starter directly to the negative terminal on the battery with the jumper cable, she would start right up. I went back and re-cleaned all the grounds. She is now starting like a champ.
Thank you again!

 

Yep, diesel is even stronger starter. At 600 amps, six volts would be lost across a resistance of 0.01 ohms, or about six feet of 12 gauge wire.

So with a diesel you have even less tolerance of poor connections.

Glad the jumper test worked out.

 

Sometimes the terminals of the battery get corroded and the didn't pass the power to the drive, you need to clean them with hot water, just rub them with a sand paper and then connect the wires and also check the connectors if they are corroded too then clean them also.

 

You can also check with your digital volt meter, put one probe in center of battery post, and other on outer edge of the connector, and crank or turn on head lights. If these is a significant drop on the dirty connection the meter will show it.

Many golf carts live on an island near me. Saw a shop working on them, they would sprinkle baking soda all over the batteries, spray on a little water, and use a plastic brush to scrub around, then rinse off. The idea is that the baking soda changes the pH of the acid coated scum on top of the batteries, and it does not eat up things below when it is washed off. Of course wear eye protecton, and work clothes. Guys that do a lot of battery work usually wear polyester, cotton easily has holes eaten in it by acid.

Once terminals are clean coating them with vaseline, silicone dielectric grease, etc. is a good thing. If you pulled out your microscope and looked at electrical terminals, you would find under magnification that the smooth metal is actaully like sand paper. The bumps touch each other, and the voids sit there collecting crud. If the crud changes physical dimension with heat/cold, it can push the bumps apart a little. So scum forms on them, too. Eventaully a high resistance connection. Sealing up with something slows down how long it takes for connector to have corrosion. My friends on the island that have waterfront property have learned to silicone grease the base of light bulbs outside. The metal to metal contact remains pretty much the same, it is the voids that are filled with inert grease.