Sluggish starting..

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Codbasher said:
Jeez Charlsey you talking about TVO Fergies??? :rolleyes: :rolleyes:


I understand what you are saying about resistance etc, but how come WHEN i do get her started she will start fine all day?? My first thought was maybe the oil was thick as hell, but it aint.
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warm/hot engines turns over much easier, ergo less work fer your KNACKERED STARTER to do
 
Codbasher said:
Jeez Charlsey you talking about TVO Fergies??? :rolleyes: :rolleyes:

My diesel Fergie had KiGass. Man up the road has it now. Yesterday he was complaining the KiGass wasn't pumping and the Fergie wasn't staring in the cold. I showed him the tap on the outlet from the kero tank, and the little darling just exploded into life after a quick heat and a squirt of kero!

My Davie Broon has a heater flame plug on the return fuel line. Works quite well, but it isn't in the same league as KiGass.


I understand what you are saying about resistance etc, but how come WHEN i do get her started she will start fine all day?? My first thought was maybe the oil was thick as hell, but it aint.
Click to expand...

Ah yes, well that is because several important starting factors stay good more or less all day.

These are
1. the engine's innards are not freezing cold - the less cold the better.
2. pistons, cylinders, and bearings are easier to move, thus upping the speed of rotation on starter - the faster the better.
3. the injection pump, pipes and injectors are "primed" full of fuel. This makes it much faster for the injection pump to hit full pressures at the injectors. Until that happens there won't be no injection.
4. the battery voltage is well up and the battery is WARM.

My Def 90 would NEVER start of a morning without a good glow (it was a big black button) but after it had been running a little while there was no need for any glow for the rest of the day.

On VERY cold conditions, it may actually help you to start a petrol Landy engine if you turn the headlights on full beam for about half a minute. The current draw across the internal resistance of the battery warms it up, and then the batty will give heaps more power for a frisky start. Guess what! Using glow plugs does the same in a diesel! Taking 60 or 70 amps for 20 seconds warms your frozen batty a treat.

The compression ratio in diesel engines is as LOW as they can get away with and still get the engine started from cold. In almost all car diesels, the CR is so low the engine will not start unless it gets a good glow, but once it's running the glow is stopped for the duration. The LOW compression makes the engine smoother, and quieter.

For a really sure cold start without a glow or other aids, will need a compression ratio of about THIRTY to one. My 1942 Lister CS has variable compression ratio. High for cold starts (about 28:1) and normal for running on load (about 20:1 I think). It will NOT start cold on low compression, but it sure does on high.

Amazing stuff we can learn on this forum huh?

I want to pass as much as possible of it on before I pop my clogs.

CharlesY
 
CharlesY said:
bloat1992 said:
I reckon it's the norm with ALL diesel engines in cold weather.
They all require tremendous temperatures to cause ignition, and that requires a whole list of things to happen, and if any one doesn't, the engine may not start. It may just pump out clouds of fuel vapour down the exhaust pipe.

My tractor has a KiGass starting aid. It is a great device.
You have a bloody big electric hot coil in the inlet manifold close to the inlet ports, and a little pump on the dash connected to a small tank of kerosene.

Stage one - Push big button and heat the coil for ten seconds till it is incandescent.

Stage two - pull out pump plunger, then shove it in smartly. This sprays a tablespoonful of kerosene over the red hot coil in the inlet manifold. There is an audible WHUMP! as the kero ignites.


Stage Three - turn the starter as soon as possible, so the pistons suck in all that lovely hot blazing kero ... a quick start is a cert!

All the parts are freely available from tractor dealers.
CharlesY
Click to expand...

So can you just go to the tractor dealers and ask for a big bag of WHUMPS ?
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Sorted...


Checked all the terminals etc, fine in mild weather still sluggish to a point of wont start in the cold, bought another earth strap from engine to Batt, no change...


So bugger it off to Halfords, biggest batt I could find 760 somthing or other, now the bloody thing spins so fast it dont need glow plugs, result.. :D
 
Which means that all the other bits that were mentioned in the thread must be in good nick, because any if one of the critical things is below par, you could fit the battery from the QE2 and it still would not start.

Hmmm.... I wonder what size battery the QE2 uses ..... ?

CharlesY
 
CharlesY said:
you could fit the battery from the QE2 and it still would not start.

Hmmm.... I wonder what size battery the QE2 uses ..... ?

CharlesY
Click to expand...
QE2'S POWER PLANT IS DIESEL ELECTRIC, a system chosen for its inherent reliability and flexibility. In 1986/87, in an operation costing £100m, nine medium speed MAN L58/64 nine cylinder turbo charged diesel engines were fitted, in place of the aging and fuel thirsty steam plant. The diesel engines drive C.E.C. generators, and each develop 10.5 MW of electrical power at 10,000 volts. Each engine weighs approximately 120 tons.
 
CharlesY, I found both your posts very informative so please don't stop with the full explanations. Not to say Slobs short sharp stuff isn't equally as useful but different strokes for different folks and I find your deconstructions simple and they paint a very complete picture.

Slob, maybe I am not typical but I am not 'just' after getting my Landy working (don't get me wrong, that is a big part of it and I really appreciate the help of this site and people like you) but I also got my Landy as an opportunity to learn all the things I never had an opportunity to as a boy. I have ample intelligence but just lack experience in electrical or mechanical engineering so my capacity for detailed posts is perfectly adequate. I could go and read a book but I personally remember far more from people than reading. Besides, I might have to read a whole book (or at least a chapter) to understand the information specific to my Landy, whereas the info on here (even the more bloated post ;) ) is always quite specific and normally going to be at least in some way relevant.

Only wanted to post as I really value this site and would hate to see the great variety of info on here diminish in any way.

Merry Christmas! I for one am off to get sloshed :)
 
OK, I'm going to throw a spanner in the works here. The standard cables - as long as they are not corroded under the insulation - are low enough resistance.
When you start the car a very high current flows through the motor creating a lot of torque, the motor rapidly spins up and produces a back Electro Motive Force. The back EMF is a voltage that opposes the battery voltage and therefore limits the current. If the motor stalls or runs slowly the back EMF disappears and the current rises until it's limited by the very low resistance of the motor windings. Hence the wires that are normally able to cope with the bit of surge current and the lower running current now carry a much greater current and get hot.
The moral is that motors are not purely resistive devices. Isn't physics fun?
 
oxides said:
OK, I'm going to throw a spanner in the works here. The standard cables - as long as they are not corroded under the insulation - are low enough resistance.
When you start the car a very high current flows through the motor creating a lot of torque, the motor rapidly spins up and produces a back Electro Motive Force. The back EMF is a voltage that opposes the battery voltage and therefore limits the current. If the motor stalls or runs slowly the back EMF disappears and the current rises until it's limited by the very low resistance of the motor windings. Hence the wires that are normally able to cope with the bit of surge current and the lower running current now carry a much greater current and get hot.
The moral is that motors are not purely resistive devices. Isn't physics fun?
Click to expand...

Basically speaking, what the man means is that when the starter motor is stalled, it is a nearly dead short electrically. Once it spins up (and they run VERY fast) the current is controlled, but it is still by far the biggest current using device in a car.

Think HUNDREDS of amps of current.

No, a 30 amp fuse won't do, nor even a 300 amp fuse!

CharlesY
 
Loads of reasons why the motor won't go round fast - seized bearings and worn/corroded commutator would be my first guesses. Time to overhaul or replace the starter - and probably the wiring, too.
 
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