/ Bump starting car

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phja - on 16 Jan 2013
My car refused to start this morning (diesel mondeo), battery had juice just not enough to start the engine. If it does the same tomorrow could I bump start it?

Am I right in thinking that by only having to heat the glow plugs rather than turn the starter motor there'll be less demand on cold battery and so more likely to start?
John Rushby - on 16 Jan 2013
In reply to phja:

You might be able to bump it, but I suspect the battery is knackered - a good frost usually kills off the little bit of life left in an old one.

You'll have to repeat the process at the other end sadly.
phja - on 16 Jan 2013
In reply to John Rushby:

There was definitely life in the battery this morning, tried starting it 5 times and still seemed to have life after 5th attempt just didn't start engine. Called breakdown, they jump started it. since then I've stopped/started it again 4 times and each time started fine really quickly. just wondering if its due to cold this morning. odd really. If it don't start tomorrow just hoping there's enough life in it to heat glow plugs so I can push start it.

Cheers!
John_Hat - on 16 Jan 2013
In reply to phja:

You may be able to bump start it, but in my experience there's a 50% chance you end up with a still dead car, but at the bottom of the hill rather than the top..

Battery charger left on trickle charge overnight works. Not only charges the battery but heats it too.

Course, running your working car to the nearest Halfords to get said charger before it shuts at 8pm might help.
Mark Morris - on 16 Jan 2013
In reply to phja: If the engine is turning, It's probably the plugs that have had it. The only time my seat Ibiza let me down was similar to this. You can buy a can of something that you spray into the airfilter inlet, That will get most engines going, Bradex Easy Start? It did my (fairly basic it must be said) ibiza diesel no harm. Didn't need a lot, just gives the diesel a chance to fire and turn the engine.
Jim Fraser - on 16 Jan 2013
In reply to phja:

Original equipment batteries typically last 6 years and after-market ones 4 years. Some more some less. If there is no known reason for the battery being low and it is near the end of its expected life then at the next hint of a problem, bite the bullet and buy a new one. However, bad batteries have a habit of breaking alternators (and vice versa) so often a second problem comes along.
ledifer on 16 Jan 2013
In reply to Mark Morris:

I agree, if your battery had enough juice to turn the engine for five start up attempts. Then I'd guess that your glow plugs aren't up to scratch.
Easy start works beautifully, but it is the kiss of death and engines quickly become addicted to it.

Personally I prefer the brand 'start you bastard'. It actually exists!
Mark Kemball - on 16 Jan 2013
In reply to phja: As others have said, it sounds like the glow plugs to me.
spearing05 - on 16 Jan 2013
In reply to phja: Just because the engine turns it doesn't mean the battery has enough juice. A diesel fires on compression so the engine needs to turn fast, just turning isn't enough. When the battery is cold it puts out much less charge.

If it is weak any way a cold morning will be enough to stop it working as the engine will need to turn faster than normal to produce enough heat from compression to ignite the diesel in a cold engine block. The glow plugs help but they're never going to heat up 50kg of frozen cast iron. At the same time the battery is producing less omph than normal.
spearing05 - on 16 Jan 2013
In reply to spearing05: My old car was the same. Started fine unless the weather was cold,engine still turned but struggled to fire. Left the lights over a weekend and totally killed the battery. New one had the engine turning significantly quicker and I never had an issue with cold starts again
Ram MkiV - on 16 Jan 2013
In reply to phja:

you might already do this but one trick which can help is to turn key to arm ignition (and the plugs) but stop one click short of turning the engine over. Wait for plug/coil light on dash to go out (will take longer in the cold) then switch back bff, do the same again but turn all the way.

> Am I right in thinking that by only having to heat the glow plugs rather than turn the starter motor there'll be less demand on cold battery and so more likely to start?

pretty much - when you turn the engine over, the starter motor takes a lot of current which causes a volt drop across the battery (internal resistance). This in turn reduces the glow on the plugs. Same reason headlights dim when you start the car.
Bruce Hooker - on 17 Jan 2013
In reply to phja:

Simple question: how old is the battery? Unless the battery is recent, ie less than 2 years old, get a new one, they don't cost much these days, and you can easily do it yourself. At least you'll get up without the worry of will the bugger start?
EeeByGum - on 17 Jan 2013
In reply to phja: Depending on what car you run, will depend on whether this strategy will actually work. The Astra I used to have had electric everything including power steering etc. My alternator went and as I was driving home the computer systematically shut everything down until the speedo / clock switched off and all that actually worked was the engine and indicators. I think that the last thing to shut down would have been the engine management computer and with that, the engine itself.

Be careful jump starting though. You can knacker the likes of catalytic converters and the like if you are not careful.
subalpine - on 17 Jan 2013
In reply to phja: could be caused by a dodgy glow plug..

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