Jump starting question

johnnyecosse · Nov 27, 2009

Reading through 1998 Disco manual online and see that it says to jump start a diesel you go onto neg terminal on flat battery (bad practice) but you go to chassis on a petrol version (good practice). As far as I was aware the reason for going onto chassis was to keep spark away from battery - thus eliminating risk of battery exploding. Anyone know why the manual makes a distinction between the two variants? The only thing I can think of is that diesels need more juice to get started and going direct to battery gives a better connection. Am I right?

colinl · Nov 27, 2009

i would have thought that putting jump lead onto chassis or engine was a better connection whether petrol or diesel?

trax99 · Nov 27, 2009

I dont care, as long as the damn car starts:car:

ratty · Nov 27, 2009

If a battery cell is fooked, putting the negative jump lead on it aint gonna help it start.

bortaf · Nov 28, 2009

I allways go to the chassis or engine block just so it misses out the dead battery and starts the vehical instead of charging the dead battery

Just what i was tought years ago.
On me disco i have to use a jump pack every morning cos the battery is fooked, if i put it to the battery i have to wait 5 mins beforei t'll spin fast enough to start, if i put the neg on the engine it spins straight away (it's one of them cheap starter packs with the siezed air pump in the back).

CharlesY · Nov 28, 2009

bortaf said:
I allways go to the chassis or engine block just so it misses out the dead battery and starts the vehical instead of charging the dead battery
Just what i was tought years ago.
On me disco i have to use a jump pack every morning cos the battery is fooked, if i put it to the battery i have to wait 5 mins beforei t'll spin fast enough to start, if i put the neg on the engine it spins straight away (it's one of them cheap starter packs with the siezed air pump in the back).

That little story is a classic description of the failure somewhere of a main connection to or from the battery, probably a main earth lead or connection, possibly of course one of the earth straps between chassis and engine. You can't have too many of those.

Your battery may not be as fooked as you think. Try this one day - First take off the NEG battery terminal and clean the post and inside the terminal. Apply a little coppergrease, and fit it back tightly. Now take a big strong black jumplead and connect one end really firmly to the chassis and then the other end to the negative battery terminal.
Now try to start the engine.

Don't use a RED jumplead for this as it will only work with positive electricity. The BLACK lead will handle negative electricity just fine.

CharlesY

PASTMASTER · Nov 28, 2009

CharlesY said:
The BLACK lead will handle negative electricity just fine.

CharlesY

Electricity is just electricity. It goes from one end of the lead (+)to the other(-). Only the colour of the plastic is different. You are taking the p, aren't you???

CharlesY · Nov 29, 2009

PASTMASTER said:
Electricity is just electricity. It goes from one end of the lead (+)to the other(-). Only the colour of the plastic is different. You are taking the p, aren't you???

Who, ME?????

Wood eye doo dat ?

CharlesY

PS - as a matter of interest, they say that DC leccy goes FROM - TO + !

Dom-300tdi · Nov 29, 2009

I've never understood the reason why a lot of car manuals suggest connecting the neg lead to the chassis rather than the battery.

Having a good few years experience building and maintaining electric vehicals, wiring sets of batteries in parrallel is commonplace and you would only ever make a connecton battery to battery.

Connecting a fully charged battery to a totally flat battery will create a very high inrush current and a few sparks but that will be the same regardless of where you connect the negative terminal. Sparks near a battery shouldnt be a problem either, theyre not unexploded bombs! The only time it could ever be a problem is if the battery has been on charge (with caps removed) for a long period of time in confined space as the charging process causes LA batteries to release hydrogen gas; but then you wouldnt be jump starting it anyway.

disco_mikey · Nov 29, 2009

CharlesY said:
Don't use a RED jumplead for this as it will only work with positive electricity. The BLACK lead will handle negative electricity just fine.

Brilliant! :hysterically_laughi

Trewey · Nov 29, 2009

CharlesY said:
PS - as a matter of interest, they say that DC leccy goes FROM - TO + !

actually, it travels in both directions at once.
electrons move from - to + and holes move from + to -

CharlesY · Nov 29, 2009

Dom-300tdi said:
I've never understood the reason why a lot of car manuals suggest connecting the neg lead to the chassis rather than the battery.

Having a good few years experience building and maintaining electric vehicals, wiring sets of batteries in parrallel is commonplace and you would only ever make a connecton battery to battery.

Connecting a fully charged battery to a totally flat battery will create a very high inrush current and a few sparks but that will be the same regardless of where you connect the negative terminal. Sparks near a battery shouldnt be a problem either, theyre not unexploded bombs! The only time it could ever be a problem is if the battery has been on charge (with caps removed) for a long period of time in confined space as the charging process causes LA batteries to release hydrogen gas; but then you wouldnt be jump starting it anyway.

WRONG!
Even with a fairly FLAT battery there is always a risk of a stray spark causing a cell explosion. Believe me, as it has TWICE happened to me. On both occasions I was lucky that there were quick people close at hand and a bucket of water both times.

The last time was only two years ago. It was a decent size 12 volt battery on a cherry-picker thing, and it BLEW UP as I connected the negative lead. It blew up right in front of my face.
The whole battery was blown to bits like a small bomb, and I was covered in sulphuric acid. The tops were all on the battery, and it was NOT on charge.

TAKE CARE GUYS! Lead-acid batteries can and DO blow up.

It does no harm and costs NOTHING always to have a plastic pail full of water somewhere nearby when working on your Landy. Don't waste any time if it happens! Slosh water all over every bit of you the acid may have reached.

CharlesY

colinl · Nov 29, 2009

i had a battery explode on a ford cargo and all what was left was the battery terminals!!

PASTMASTER · Nov 29, 2009

CharlesY said:
Who, ME?????

Wood eye doo dat ?

CharlesY

PS - as a matter of interest, they say that DC leccy goes FROM - TO + !

I demand the return of my urine. (Or a pint of lager - much the same thing).

PS - Of course they say that. Yes I was wrong. I shall flagellate myself accordingly.

CharlesY · Nov 29, 2009

PASTMASTER said:
I demand the return of my urine. (Or a pint of lager - much the same thing).

PS - Of course they say that. Yes I was wrong. I shall flagellate myself accordingly.

What grade of spark plugs do you recommend for a 200tdi Disco?

CharlesY

PASTMASTER · Nov 29, 2009

CharlesY said:
What grade of spark plugs do you recommend for a 200tdi Disco?

CharlesY

I know it can be very difficult to get the original Russian ones - apparently LR have them on back order. In the meantime, I'd say any tractor ones should do. So long as you change the filter regularly.

Trewey · Nov 29, 2009

PASTMASTER said:
I know it can be very difficult to get the original Russian ones - apparently LR have them on back order. In the meantime, I'd say any tractor ones should do. So long as you change the filter regularly.

and don't forget to clean the carb jets from time to time.

LundRover · Nov 29, 2009

We are not allowed to import Russian or Ukrainian Spark Plugs into Britain because they are designed to work only with old Soviet style 'RED' electricity, and here in Britain (read the EU) all of our Diesel Engines are designed to use 'Multicultural' electricity to generate sparks in the combustion chamber. In other words, our electricity has to pass many more tests than Russian electricity does.

ratty · Nov 29, 2009

Sorry for asking such a newbie question. My TD5 has been taking longer to start in the mornings, How often do I need to defrag the ECU to help it start quicker. Many thanks.

PASTMASTER · Nov 29, 2009

ratty said:
Sorry for asking such a newbie question. My TD5 has been taking longer to start in the mornings, How often do I need to defrag the ECU to help it start quicker. Many thanks.

I think the previous advice to clean your carb jets may be the problem here.
Sorry, I mean the solution.
A J-cloth or similar supermarket's own-brand may be enough. Have you checked the HT leads for oil ingress?

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