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Logical diagnosis and guessing. - David W
The exchange between KB and Kev on the Jump Leads thread made me think of the several phone calls from a customer over the past few days.

All I was saying on the jump lead thread was that the cheap leads are often so poor at passing current they will not enable the start, particularly of a larger or diesel engine.

Hence when I have a call about a car stuck somewhere that won't start and I'm told it can't be the battery because they've tried it with jump leads.....well then I try and find out if they were decent leads or nothing is proved.

Communication is the key to helping someone over the phone and logic the key to problem solving. This is what I was faced with the other day.

Phone call about a 1.9 Turbo Diesel that wouldn't start. "Since it's been very cold it has taken ages to start and been really lumpy, now today it turned over a few times and then the battery was dead" the guy (regular customer) tells me. So I'm thinking battery and/or glowplugs.

For various reasons I couldn't get to him quickly and he said it was easier to use a local mechanic where the car was stuck.

Next day I get a call again.."We changed the glow plugs and charged the battery but it still won't start, it's just the same". Now my head is racing to think of all the other things it could be. Wondering abvout the starter motor or a diesel system fault etc. After a few minutes he happened to mention the huge cost of the glow plugs at £15 each so they'd actually only changed two. I asked if those were the two that failed test. "No", he says "we changed the two that were easiest to reach, the others looked pigs to get out". I had to explain there was every chance they had replaced two good ones and left in the duff plugs.

I was still puzzled it wouldn't eventually start with a fully charged battery so asked how long it had been on charge (expecting to hear overnight). "Oh the mechanic jump started us and we used the car to fetch the plugs (a 7 mile journey), we didn't use the heated rear window much so thought it would be fully charged" Now this on a day when you needed the heater blower on full and the headlamps on!

I got him to put the thing on charge the next night and it turned over OK so we've booked it in soon for a sevice and proper diagnosis of the glow plugs.

Ho hum.

David
Re: Logical diagnosis and guessing. - Julian Lindley
David,

Your anecdote well worth reading. Theres none so queer as folk!

Your note reinforces the point of ensuring a thorough debriefing of the owner of the problem car or otherwise.

Regards,


Julian
Re: Logical diagnosis and batteries - steve paterson
David,
A couple of years ago I read a Ford TSB relating to flat batteries and jump starting. Depending on battery capacity and alternator output, it takes up to 8 hrs of 'normal use' before a battery is fully recharged by the alternator.
Steve.
Re: Logical diagnosis and guessing. - Adam Going (Tune-Up Ltd)
Hi David, and a Happy New Year !

At least you and I, and lots of the other contributors here, actually get to talk to the customer/driver and ask the questions we want answers to. Pity the poor garage mech who only has what is written on the job sheet, or mumbled by the receptionist, to go on. I have long since said that the best on-board diagnostic system in the world is the driver, providing the right buttons are pushed !

Regards, Adam
Re: Logical diagnosis and guessing. - THe Growler
Having taught professional problem-solving/decision-making techniques in a business environment many years, I can say the two biggest obstacles are (a)"jumping to cause", i.e. it must be the whotsits because we've replaced the thingummies" and (c) expressing the problem in terms of perceived solutions, e.g. "I need a new battery, this one won't hold a charge" when the loss of charge is due to something else.

Both these sidetracks tend to get bought into by everyone on the case, with resulting blind alleys and time-wasting.

Well worth anyone's time picking up some problem analysis skills and techniques. Plenty of books.
Re: Logical diagnosis and guessing. - Colin Standing
Task and problem analysis I like in many ostensibly hum-drum situations.

Good teaching technique I like even better.

So, OK, I've fallen for it , Growler.

What's (b) ?

Happy New Year

Colin S
Re: Logical diagnosis and guessing. - Brian
Quite a few years ago I had a case of the battery running completely down on a long journey.
It was a filthy night and I had everything on, lights, heater, rear window, wipers, radio.
The traffic was very, very slow and I got home about 8.
Tried to go to get fish and chips, but the battery would not turn the engine over.
Put it on charge overnight and it was perfectly OK. the slow speed and high load had just run it right down.