why did this happen

[katellwood]

Just taken my wifes peugeot diesel to the Mechanics with a starting problem, had to jump start it from my Land Rover to get it started this occurred with no problem

Upon arrival at the garage the Mechanic drops something on the battery and says that there is no problem with the Alternator however it will need a new battery, he says he will get one and drop it off at home (he's also a neighbour and a good friend)

The issue I wish to know is that to start the car to get me home he came out with a big red plastic box with jumper leads on it, he called it a jump box. We connected it to the battery and although the vehicle turned over with great gusto for some reason unknown to me it would not start or even attempt to fire.

We then used a set of jumper cables and jumped it from another vehicle, it started immediately

He said he had known this happen with Renaults but not Peugeots

Why did this happen?????????????

 

[Dibs-h]

Diesel's require "grunt" to get them started - which is why the ampere hours (Ah) on the battery is usually higher for a diesel. My old Audi 80 diesel with a flat battery wouldn't jump start from a petrol Vectra but did from a Avensys diesel - the make has nothing to do with, just that petrols don't need much grunt to start them and obviously the charging systems are designed for the car - not for what you might possibly want to jump off it.

When he\you fit the new battery - see what the battery rating is. It will say XAh on the front usually. So if you need to jump it - the "other" car usually needs to have a battery (charging system) that puts out that or more.

Also - the jump pack (just a portable battery with leads) might not have been fully charged or possibly not rated enough (ampere hours) for your diesel.

HIH

Dibs

 

[nev]

+1 for what dibs says.
probably enough juice in the battery to spin the starter but not enough to spin the starter AND power the ignition circuitry etc

 

[Blister]

On older diesel engines you have a glow plug light

This comes on for a short period to warm the glow plugs

If the battery cant provide enough power ( amps ) for both the starter to spin the engine fast and also provide high enough power to heat the glow plugs a starting problem occurs

 

[Eric The Viking]

One cold weather diesel trick it to turn the ignition on, count to ten, turn it off and count to ten again before starting.

It does two things: gives the glow plugs two bites at the problem, and the first go with the glow plugs warms the battery, so that it's working better chemically the second time. It seemed to work with the old TD engine in my Landy, but the replacement TDi is such a good starter that glow plugs are rarely needed, even on the coldest days. It will help a failing, but not completely dead, battery to get that extra oomph to turn the engine over.

Regarding jumping diesels with petrol engine batteries, I think it's simply that you need a certain RPM to get them going, and petrol engined-car batteries simply aren't man enough.

It's really nice having a glow-plug light, and a simple engine

 

[Tom K]

The issue I wish to know is that to start the car to get me home he came out with a big red plastic box with jumper leads on it, he called it a jump box. We connected it to the battery and although the vehicle turned over with great gusto for some reason unknown to me it would not start or even attempt to fire.


Why did this happen?????????????

Did he connect the earth lead to the battery?(Wrong) Or to the engine block?(Right)

 

[Phil Pascoe]

Tom - not a lot people know that! +1

 

[Eric The Viking]

It can't be all that significant, surely?

The difference is only the resistance of the earth strap: although that will put the most volts across the starter rather than the battery, it's pretty marginal, as long as the strap is sound (and thick enough in the first place). It certainly shouldn't be higher resistance than the jump leads themselves.

Or am I missing something?

E.
(you can tell I'm bored with HTML/CSS/PHP already this morning!)

 

[theartfulbodger]

amp hours is just the capacity of the battery....cca cold cranking amps is how much grunt it has :ho2

 

[Phil Pascoe]

Failure to start, especially in older engines is quite often a combination of different weaknesses - if there is a poor earth conection it may be the straw that breaks the camel's back. If you look at new jump leads, the method is often on the pack. Some 20 years ago I came across a friend who had broken down - he had called out his neighbour, who was a retired mechanic, and they were trying to jump the car without any joy. I suggested putting the neg. lead on the engine block, and the guy said he'd never ever heard of that, but tried it, and the engine started first time.
I had a landrover years ago that I had endless trouble starting - I put another earth strap on it, on different mounting points, and didn't have any more trouble.

 

[Eric The Viking]

Failure to start, especially in older engines is quite often a combination of different weaknesses - if there is a poor earth conection it may be the straw that breaks the camel's back. If you look at new jump leads, the method is often on the pack. Some 20 years ago I came across a friend who had broken down - he had called out his neighbour, who was a retired mechanic, and they were trying to jump the car without any joy. I suggested putting the neg. lead on the engine block, and the guy said he'd never ever heard of that, but tried it, and the engine started first time.
I had a landrover years ago that I had endless trouble starting - I put another earth strap on it, on different mounting points, and didn't have any more trouble.

Fair enough.

My own Landy died mysteriously eighteen months ago, outside the local shops. It turned out to be the positive strap to the starter relay/solenoid - snapped inside the boot, on the terminal. To my shame, it took the RAC to find it - it simply hadn't occurred to me that it might break. The earthing points on Landys are the stuff of nightmares though!

E.

 

[katellwood]

Guys

Thanks for the replies, when the car (a Peugeot 307 HDI 110 bhp with over 150k) was attempted on the jump box it was still warm from the initial journey to the gge, in addition when we eventually got it going it was jumped off of a petrol Nissan Micra this being the closest vehicle to the Peugeot.

Does the injector pump need a large amount of electricity to work or is it mechanically powered?

Finally when I put the new battery on it cranked without starting for approx 15 - 20 seconds then burst into life been OK since

One final question, does power to the vehicle maintain some sort of vacuum to maintain diesel in the injectors and when disconnected the vacuum is lost and diesel flows back to the tank, so in effect when you reconnect the system automatically rebleeds itself when you crank it over.

 

[deserter]

If I remember correctly my dads snap-on jump charger thingy tells you only ever to connect the negative to the block or earth point and never the battery.

 

[Cheshirechappie]

I think it's just that the jump box couldn't speak French.

 

[katellwood]

I think it's just that the jump box couldn't speak French.

:lol: Brilliant =D>

 

[theartfulbodger]

One final question, does power to the vehicle maintain some sort of vacuum to maintain diesel in the injectors and when disconnected the vacuum is lost and diesel flows back to the tank, so in effect when you reconnect the system automatically rebleeds itself when you crank it over.

Pass! All I know is that the LR Td5 engine primes the pressure in the fuel system when you turn the key to the "warm up" position prior to firing up the starter motor...it's possible that other manufacturers have something similar, though common rail diesels run at a very high pressure.

I'm not sure diesel would ever flow back to the tank, if there was any flow at all the fuel pump should sort it out pretty quickly.

 

[Tom K]

It can't be all that significant, surely?

The difference is only the resistance of the earth strap: although that will put the most volts across the starter rather than the battery, it's pretty marginal, as long as the strap is sound (and thick enough in the first place). It certainly shouldn't be higher resistance than the jump leads themselves.

Or am I missing something?

E.
(you can tell I'm bored with HTML/CSS/PHP already this morning!)

If you connect direct to the faulty battery the charge from the jump box is sapped, effectively trying to charge the defective
battery instead of turning over the engine.