General question about jump starting

troubleinstore in news:cs11c5$s10$ snipped-for-privacy@news8.svr.pol.co.uk, typed something a little like this (allegedly):

Think it may have something to do with the cam belt and the load you put on it causing it to fail or weaken, but I could be wrong.

As for the AA and RAC, I have never seen this. I have only seen them use jump leads.

Apart from the obvious safety aspect of a car suddenly starting or trying to bump start on the hard shoulder. Why would bump starting affect the cambelt? It surely can't be much worse than the starter motor can it?

Think we are confusing JUMP start with BUMP start, which are of course two different things.

You can jump start a modern car with no problems, as long as you make sure you get the leads the right way round first time!

You CAN bump start a modern car (Im assuming a flat battery) but its not recommended because of things like:

The fuel injection system has to be pressurised, which takes 12v power to run the pump, making it harder to bump start (cos you have to push longer when in gear lol)

Catalytic converters dont like jump starting, cos you can get unburnt petrol into the cat, which I understand can reduce the life of, or ruin the cat

Think thats the main reason. Im sure a few petrol heads will add a few more.

Oh I have a question..

Can you BUMP start a diesel car??

John.

Yes you can bump start an older diesel(turbo or not) car, as long as you have enough electrical power to turn on the fuel stop solenoid.

Of course a modern PD-TDI or HDI with electric injectors would be a different matter I guess. My other car is a VW Touran, 140hp 2.0 16v PD-TDI - It says in the manual NOT to try bump starting, but does not give a reason?

Andy

Gentlemen, above I asked about JUMP starting, not bump starting ..... ! i.e. using leads from the battery of one vehicle to the battery off another

-- troubleinstore Email address in posting is ficticious and is intended as spam trap Personal mail can be sent via website.

Assuming the Jump start is done correctly, connecting the earth to the engine, not the battery, I cannot see any reason why not to Jump start.

Andy

Just check the manual. Some of the newer cars have such delicate ECUs that they may not be jump started.

IPG

He has got confused.

Modern cars don't like to be BUMP started - partly cos the injection system won't work without power, and partly cos the Cat doesn't like it.

JUMP starting is fine. Providing it's done properly, it's exactly the same as starting the car from it's own battery - it obviously doesn't care where the power is coming from !

Something in the back of my mind reckons that some ECU's prefer it if the two cars remain connected with the engines running for quite a while or there can be problems with the receiving one. I am not entirely sure if this is true or not, maybe someone who really knows could enlighten us.

Ron Robinson

Jump starting with leads,,,, Just make sure the ignition on the receiving car is turned OFF, Fitzy

"R.N. Robinson" wrote in message news:cs3hmm$o58$ snipped-for-privacy@news6.svr.pol.co.uk...

Mines (205DT) been bump started and jump started before :) However they are harder to bump start becuase of the higher compression ratio. Wouldnt like to try bump starting it when cold at this time of year though!

Presumably you mean when disconnecting, in which case the cars would have had to stay connected long enough to put a useful amount of juice in the receiving battery so that it can restart its car. Unlike old-fashioned systems where you just start the receiving car and whip the leads off as soon as it is running (donor end first if you haven't connected the earth lead well away from the battery)

Ron Robinson

Once the engine is running on the car needing the jump start, you can disconnect the leads however you like, no need to turn off the car to do this (however modern the car) as there will be power in the system, albeit very little, but enough to keep the engine going.

A much easier trick is just to rev the jump start recieving car so that its charging faster while your mate disconnects the leads (safely, of course), worked on my mates HDi!!

providing the alternator is charging the battery, then the engine should keep running after jump leads are disconnected, as "JC" has already said, I would advise disconnecting the earth lead (black) first though, its considered safer,,, if you accidentally drop it on the engine or body, it wont short out, but the live (red) if dropped will short and do damage,

Fitzy

Quite right there Malc, With the key,,,,,,,,,,,,,, Starter turns the crankshaft,, crankshaft turns the cambelt,

When car is push started or bump started ,,the wheels turn the gearbox the box turns the crankshaft via the clutch,, the crankshaft turns the cam belt, so you are right,,,,,,,,, no different HTH Fitzy

I've found that a tow start is easier on a diesel.