Starting a diesel

[lw395]

Generally, an indirect injection diesel will need to be preheated, a direct injection won't. ...

Yanmar GMs are indirect and have no preheat or heater plugs.
They are generally easy to start, provided the battery is up to scratch.

But I think they have a pretty powerful starter motor in relation to the cylinder size?
To start a diesel, you need to get the air in the combustion chamber hot enough. That means compressing it far enough to generate the heat and fast enough that the heat doesn't escape.
Spinning the engine too slowly will allow some compression to leak away via piston rings and valves. Also due to the valve timing some compression is lost at very low rpm.
I guess yacht engines don't need to be designed for sub zero starting.

Do volvos have lower compression? different valve timing? weedy starter motors? different bore/stroke ratios? Heavier flywheel?

My diesel car has only once lit up a 'preheat' light when I pushed the 'start' button. It waited maybe 10 seconds before cranking. It had been minus 10 or something overnight and the car hadn't been used the day before. Once it decided to crank, it started 'just like that'.
It's not a volvo.....

 

[PCUK]

I'm intrigued by the requirement for horses?

Neigh, neigh, I'm bridling at this. I wrote it on the hoof.

 

[PCUK]

Sounds fairly straightforward. Easiest plan would presumably be to mount it straight through the wall of the air intake, at 90 degrees to the inlet body, but should it be directed along the airflow path, towards the filter? I'll try to attach a pic of the engine if that helps to explain what I mean...

And while we're at it, I'm inclined to try a self-contained reservoir to keep the plumbing to a minimum - any suggestions for a suitable receptacle (or ideally pics/links, just so I can get the idea clear in my head) What should the pipe be made from?

Thanks!

It goes in through the side. No need to be inline with air flow.. Just to confirm it is fitted on the engine side of the air filter. if you've got CAV filters then there should be a spare outlet to couple the feed from. Otherwise any metal tin with a screw top will do.

 

[Rappey]

A bmc glowplugs is very small and barely 6 amps. The surface of the plug gets coated in carbon so they need a good 30 secs or more preheat. A plus is that they are £4.99 each !
My common rail car has 24a glow plug.

 

[ghostlymoron]

In the sixties I was for a time a junior site engineer and our site transport was a Winget dumper. In the winter we used to light a fire under it to make starting easier before hand cranking furiously and throwing the decompressor.

 

[Refueler]

Sounds fairly straightforward. Easiest plan would presumably be to mount it straight through the wall of the air intake, at 90 degrees to the inlet body, but should it be directed along the airflow path, towards the filter? I'll try to attach a pic of the engine if that helps to explain what I mean...

And while we're at it, I'm inclined to try a self-contained reservoir to keep the plumbing to a minimum - any suggestions for a suitable receptacle (or ideally pics/links, just so I can get the idea clear in my head) What should the pipe be made from?

Thanks!

As another says - the themostart is on the engine side of air filter directly screwed into the intake pipe. .... and should not be too much distance from the actual engine .....
There's no fine art to this ... the act of engine drawing in air will pull the heat ...

Pipe ? I use clear plastic diesel pipe so I can see the fuel .... the connection to the plug does get hot if powered too long - but a suitable heat resistant clear fuel pipe will survive.

Any small reservoir ... even a large syringe without plunger is enough ... the amount of fuel needed for a start is miniscule .... literally less than a tear drop !!
I actually use the pipe itself as my reservoir ... its about 6" long and has a larger pipe pushed over end as a friction fit to allow a slightly larger hole for me to fill the first pipe ... when the plug valve used to work properly - it was good for a number of starts ... but the plug valve developed a trickle leak and now if needed - I top up the pipe before use.

I have a small plastic 100ml bottle ready to create a new reservoir ... it has a nipple outlet ... all it needs is a hole made to fill it and a simple pop stopper .... if you've ever refilled printer cartridges - you usually get pop stoppers in the kit ... the bottle in fact is from same kit !

 

[duncan99210]

As an aside, the Bedford MK and MJ series military 4 ton trucks had a cold start device fitted for use in sub zero temperatures. It consisted of a closed cup and pump in the cab: you removed the lid from the cup, placed a capsule of ether into the cup, replaced the lid and pressed a plunger down to puncture the capsule (looked quite like a Tasimo capsule iirc) and then pumped furiously to get the ether into the inlet manifold. Then turn the engine over. Seemed to work quite well if the ether capsules were intact, all too often they’d got punctured in storage....

 

[doug748]

Here is an interesting piece from Sir Tom, on starting a semi diesel engine.
If you just want to see the engine fire up, go to c 3min in:

I used to like my old Petter which had a plunger on top so you could conveniently give it a direct shot of engine oil. Always thought it was a great policy.

 

[rotrax]

First Mate and I zoomed over to Czechoslovakia in the late 80's - a year before the wall came down. We drove over in a Fiat Uno 1.7 Diesel. It had never been a problem to start in the two years we had had it.

We had a great time and stopped on the way back at Marianske Lasne, a beautiful Spa town as well as having the Longtrack circuit which I regularly performed on during the racing season. We stayed at the Hotel Speedway which, surprisingly enough, we were regulars at. Its rear overlooks the track.

We had a great evening, a really nice meal with music from a local band and even a bit of dancing - if you can call it dancing with me trying a Polka with a mature Czech woman!

Next morning it was quiet - really quiet. A look outside told why. Overnight a white out, over half a metre of snow, minus 15!

We could not even see the poor fiat, it was just a lump in the snow. I borrowed a yard broom and cleared a lot of the snow off it, scrounged a plastic bag full of hot water to thaw the door locks and seals and managed to get in.

Not a chance of it starting, far too cold.

I removed the complete air filter and then went into an abandoned greenhouse where I found a plant cane. I tied a duster to it, poured a little diesel from our emergency can on it, lit it and waited untill it was really going.

First mate cranked it while I allowed the inlet manifold to suck in the flames. It started quite easily.

With very cold fingers I put it back together and we left it running while we had breakfast.

The journey from there to Wurzburg was a bit touch and go, but we made it, no chains or winter tyres.

A trip neither of us will ever forget!

 

[Beneteau381]

New boy on here and diesel does not really bother me as have a Hurley 18 with outboard but it has always something I have not fully understood.
When a guest on other peoples boats, some start on the button, others need to have some heat device. From my personal experience I used to have a Tranny van that would always instantly start by turning the key, after changing to Peugeot I had to wait for the light to go out before it would even think about starting.
Question is, why?
Surely a diesel is a diesel is a diesel.

Depends on the compression ratio, wear on the engine, direct injection engines usually light up straight away, indirect needs a glow plug. Generally speaking!!!!!

 

[Beneteau381]

Bedford ? All Bedford TK's ... TM's I rode in had Cold Start levers - that basically bypassed the governor on the pumps and allowed larger volume of diesel to be injected ... no glow plugs or thermo's.

In fact Leyland Bedford ended up removing the pull lever from the cab and putting it outside under the rear of the cab same as Fords ... to stop drivers pulling it out to get up hills !!!

Really?

 

[Beneteau381]

The Thermostart produces a flame that is drawn into the cylinders providing heat exactly where it is needed. Far more efficient than heater plugs.

I believe the aim was to gasify the diesel which had a lower ignition temperature. Diesel fuel known as gasoil in most eu countries.

 

[Beneteau381]

As regards using aerosols to start an engine (not including Easy Start) it was the propellant that did the work, not the spray., many now use a non flammable propellant.

"(CFCs) were once often used as propellants,[18] but since the Montreal Protocol came into force in 1989, they have been replaced in nearly every country due to the negative effects CFCs have on Earth's ozone layer. The most common replacements of CFCs are mixtures of volatile hydrocarbons, typically propane, n-butane and isobutane. Dimethyl ether (DME) and methyl ethyl ether are also used. All these have the disadvantage of being flammable. Nitrous oxide and carbon dioxide are also used as propellants to deliver foodstuffs (for example, whipped cream and cooking spray). Medicinal aerosols such as asthma inhalers use hydrofluoroalkanes (HFA): either HFA 134a (1,1,1,2,-tetrafluoroethane) or HFA 227 (1,1,1,2,3,3,3-heptafluoropropane) or combinations of the two. More recently, liquid Hydrofluoroolefin (HFO) propellants have become more widely adopted in aerosol systems due to their relatively low vapor pressure, low global warming potential (GWP), and non flammability "

I beleieve WD40 used to use propane or similar, thats why it was good as a starting aid. As others have noticed, it no longer works. The starting fluids using ether, hence the smell, ether will go bang on fairly low compression. The reason it damages diesels is that the ether bangs as soon as it gets hot on the firing stroke, usually before the ignition point in the cycle. So it causes pre ignition. Damaging to pistons and ring lands. Using it in a petrol engine isnt so bad, the lower compression means that it doesnt usually ignite on the compression stroke on its own. It has to have the spark. This then allows the engine to fire at the correct point, ie no pre ignition.

 

[WFA]

From scraps of memory lane:
Sump heating was common place for military, emergency services and cold environment operators - usually "Black Heaters" which were electric or safety paraffin heaters (as in the green house) which were placed on the floor beneath the sump with a reasonable air gap . Yes they kept the engine warmish but more importantly they kept the oil sufficiently fluid not to retard the initial cranking speed on startup which was always after the heater was safely removed.
Thermostarts leaked (used to but things may have changed) because they relied on a ball bearing to seal off the fuel feed which was gravity fed from a small canister. The canister tap had to be opened and the ball bearing then "opened" on expansion of a coil heated when a 12v plug was energised by a remote push button to ignite the fuel. Once the engine was running there was no guarantee the operator would shut the canister tap or that the coil would retract sufficiently to allow the ball bearing to seal the diesel feed which, as we all appreciate, is a difficult task for most diesel fittings. In short, unless properly and carefully maintained they leaked.
Blow lamps were used to carefully warm a cast iron or steel manifold prior to starting then the lamp was extinguished, turned on again but not ignited and the smoking paraffin vapour was directed into air filter which would in turn assist the initial start.
A burning or smoldering oily rag is the an obvious but risky development of the previous two but best not practised in the confines of a marina - if at all.
Injection Pump Excess Fuel in various forms basically enables the pump to override the fuel governor settings and deliver excess fuel to each injector until the engine fires up and the governor regains control. The excess fuel helps raise the initial combustion ration as well as insuring there is sufficient fuel on first delivery. The Simms/CAV Minimec pumps for instance had/have an excess fuel button (which few operators knew about ) which releases the fuel rack to its full extent. Less sophisticated Enfield engines had a fuel stop quadrant which when released would do the same by default.
Decompression and Compression aid. Many two stokes have decompression levers that enable the engine to be cranked by hand to a suitable speed before releasing for compression to start. Listen for injector "buzz" or squeak to confirm you have atomising fuel in the cylinders. On some two stroke cylinder heads there is a small knurled plug which allows the operator add small quantity of oil which increases the compression ration on starting.
Ether Capsules, often fitted to hand start engines entailed placing an ether capsule in a container fitted with a small plunger which was piped to the inlet manifold or filter. Pierce the capsule in the container at an appropriate time when cranking. A tricky business when cranking, operating the decompression lever and bracing your self in a small rolling boat.

Because of modern restrictions on noise, air and water pollution, modern diesel engine fuel combustion has become a more refined process than before so the best way to ensure your engine starts and runs smoothly will depend on knowing when you engine was built and technology involved. However, as many have said above, the same principles apply for all diesels whatever their age because they are designed as compression ignition engines - deliver air, fuel, compression at the right time, quantities and temperature and the engine will run.

 

[JumbleDuck]

If you are cranking away, should you be keeping at it as you have heat building up in the cylinder, or it doesnt matter and you can wander off and come back and try some more?

If you need to crank for more than a few seconds you have a problem which should be sorted out.

Edit: In the case of my new engine, which started needing lots of cranking, the problem was an intermittent open circuit in the fuse of the glowplug circuit. Took me five minutes to find, but not until after I had run up a yard bill of almost a grand trying to find the problem. Intermittent faults are a bugger.

 

[JumbleDuck]

Carb cleaner is usually (or at least it used to be*) trichloroethane 1.1.1. which doesn't ignite readily but can decay into something truly hideous like zyklon B when heated.

I once in my younger days made the mistake of try to set fire to a bit of blue roll soaked with Genklene, which is the same stuff. The genklene didn't burn but the blue roll did and within seconds I was fighting my way to the door of the lab. Hiydrogen chloride fulmes, as I recall, and I think there may be some chlorine in there too. Not nice.

 

[JumbleDuck]

Here is an interesting piece from Sir Tom, on starting a semi diesel engine.

There is an excellent collection of old marine diesels at the maritime museum in IJmuiden, and they run them on (iirc) the last Saturday of every month. Well worth going to see if you're in (a) terested and (b) the area.

 

[Rappey]

We should be thankful we don't have to go through this to start our engine

 

[JumbleDuck]

This isn't my video, but I've been there and seen it - starting the Mull of Galloway lighthouse foghorn compressor engines. It's quite a palaver, as they start on petrol and then have to be switched over to diesel.

 

[PCUK]

Really?

Nothing as scientific as that. A heating coil opened a valve and ignited the diesel causing a flame that was drawn into the cylinders as the engine cranked.