Battery problems

I've recently replaced the injector pump on my 200 Tdi, now iw won't start!
When I turn the key it clunks, stops, and the dash lights go out. The battery was charged, so I suspected a dodgy earth. I connected the battery earth to the engine with a jump lead (quite a heavy duty one, about the same thickness as the battery leads) and it turns over very slowly, as if the battery's almost dead, and the jump lead itself gets hot very quickly.
Is there something else I can try before I buy a new battery? I've cleaned up the earth connections but it made no difference.

Seams like that lead may not be up to the job,has it got the proper connections? What's wrong with the original earth from battery to gearbox?
Re check all connections and recharge the batt.

tottot said:

Seams like that lead may not be up to the job,has it got the proper connections? What's wrong with the original earth from battery to gearbox?
Re check all connections and recharge the batt.

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Nothing wrong with the original earth, but it did get some diesel on it when I was changing the pump, so I used the jump lead to test whether the earth was the problem.
After I try to start it, althought the starter has hardly turned the battery needs charging again, so I'm thinking it may not be holding a charge.

Do a voltage drop test to determine if battery voltage is actually getting to the starter. It needs to be a drop test rather than simply reading voltage across starter terminals. The results of this should point you in a more focused direction to concentrate your diagnosis.

Also another consideration, based on the fact that the engine turns slowly, would be to physically turn the engine by hand. I appreciate that on a diesel this can be more hassle than a patrol where removing spark plugs will reduce compression enough to make it an easy task. I would still try it though and if there seems to be undue load, something you will have to gauge rather than measure, you can then remove the auxiliary drive belt to eliminate anything driven by that belt. I guess another way would be just remove the aux belt and spin it over with the starter and see if there is a difference.

wattfield said:

Nothing wrong with the original earth, but it did get some diesel on it when I was changing the pump, so I used the jump lead to test whether the earth was the problem.
After I try to start it, althought the starter has hardly turned the battery needs charging again, so I'm thinking it may not be holding a charge.

Click to expand...

Right time of year for battery probs, they always fail as the temperature falls.
Top it up and charge it, if the problem persists its probably a goner. Most battery places can test them for you if you dont have a meter