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Diesel engine reluctant to start.- lots of photos on page 4


dave21478
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Hello,

I bought a new toy the other day.

its a slightly tattier looking one of these...

[img]http://nl.gslopsema.nl/images/news/Neuson%205001%20Klungel%20%2022.09.2008%20001.1.jpg[/img]

Will it start? Will it ****.

Its a 3 cylinder Yanmar diesel engine with a wee turbo on it.

The pre-heat works fine, but the engine turns over and over without a

hint of firing. But, give it a tiny (less than half a second) puff of

coldstart spray in the intake and it fires up first turn and once

running, works perfectly. Power is good and it doesnt smoke at all.

Kill the engine and if you restart within a couple of minutes, it will

start ok, but any longer and it will need another puff of coldstart to

get it going.

preheat definately works.

compression is good, so no problems suspected there.

Perhaps worn/dirty injectors? if their spray patern wasnt great would

this give these symptoms? I would have thought it would smoke a bit in

this case.

Any other suggestions?

Thanks,
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Your logic is 100% correct re preheat first and compression second, the dirty injectors are not likely to give a problem after resting a few moments and would as you say result in smoking.

It sounds to me that the engine control is not recognising that the engine is cranking and is not releasing fuel to the injectors or not switching on the injectors depending on what type of injection. It is able to fire on the easi-start from compresion ignition and then at idling speed the (probably) crank sensor signals are being correctly received.

The fact that it will not restart after only a few minutes of shut-down leads me to exclude all of the more obvious causes which are usually only evident and exarcerbated by extremely low temps.

Find out what type of engine speed sensor is fitted and then check all connections, airgap if appropriate and or clean up magnetic or hall sensor elements.

I am jealous of your new toy, will one of its first outings be to exact revenge on the guy that had you over, I dont mean the guy that sold you it but the one who didnt pay you for the digger hire charges.

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Fortunately (or not as the case may be) there is nothing as sophisticated as that, there is no management or control units. Its a mechanical injection pump, and the stop solenoid is about as complicated as it gets electronically. Modern electronics are just voodoo to me. As you can imagine, there are all manner of extra wires and disconnetcted wiring all over the thing that have been jiggered with by previous owners over the years, but none of it apears to be anything really engine-related. There is a stepper motor on the thottle arm, which is unplugged, but I think that is some form of anti-stall system, or something that prevents you forcing too hard at low rpm. Either way, its nothing to do with starting the thing.

The preheat is slightly unusual in that it doesnt have glowplugs as such. There is a heater element in the inlet manifold after the turbo, which heats up nicely ( burnt finger tips to prove this!) and an electro-valve that drizzles diesel over it, which ignites in the manifold and fires up the engine. Its impossible to see it in action, but the element works and diesel arrives at the nozzle, so I see no reason why it shouldnt work. I have a we Yanmar compact tractor with the same system on it, and it works well enough.

Its bound to be something butt-clenchingly simple that I have overlooked, but for the life of me, I cant think what it might be.

That chap did eventually pay up in the end, and I didnt even have to rip up his garden again! He just turned up out of the blue with the money and profuse apologies.

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[quote user="dave21478"] Its a mechanical injection pump, and the stop solenoid is about as complicated as it gets electronically. and an electro-valve that drizzles diesel over it, which ignites in the manifold and fires up the engine.[/quote]

One of these is not actioning when it should be, first check to see if the stop solenoid is fail safe by unplugging it when the engine is running, if it stops then  hot wire it direct to the battery and then try starting the engine, if no change then you can rule that out.

Then try the same sort of manual control on the electro-valve by holding a hot wire to it for a couple of seconds whilst cranking.

Editted you should first make sure that the electro valve is actioning and not blocked

I reckon one or the other will coax it into life but then you have to decide what is causing the problem i.e. what is preventing the valve from operating, in either case it may be some kind of engine running or position hall type sensor probably on the flywheel.

Or alternatively having found a less messy way of starting than using easi-start continue using the hot wire, I had a very similar problem with an injected Scirocco GLI which I suspected was the thermo-time switch, in my lunch time I made up an override switch out of a rubber and two drawing pins (I was a draughtsman at the time) and wired that in series with the solenoid, after that it was simply a case of pressing the two pins together long enough according to the degree of frost to prime the inlet manifold and she would start easily, the £35 to replace the switch was a lot of money to me then and winter would soon be over, the digital idle stabiliser electroncs box (similar to your stepper motor) was consigned to the dustbin for the same reason.

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  • 2 weeks later...
Still cant get it to start normally.

The pre-heat system definately works as it should.

I had the injectors out and took them to a chap I know with a test rig. They are all ok, good flow and spray pattern.

I re-did a compression test to make sure and it still reads evenly - 18 bar across all 3 cylinders. Thing is... I am having real difficulty finding out the engine specs online to see if this is a reasonable reading or not. The injector guy reckoned it should be 22 bar (dont know where he gets that figure from) but thats for the non-turbo version. A turbo engine should normally run lower compression, but how much lower in this case, I dont know.

If it is lacking compression, Im not convinced its worn bores/rings, as when running it runs perfectly, uses no oil and doesnt smoke in the slightest. Perhaps the valves need lapped?

I took the rocker cover off, and the rocker gaps are all even. Again, I dont know what they should be set to, but there is nothing obviously wrong. I simply dont have the time to take the head off just now, and would much rather have a tech manual to check the specs before I start taking things apart.

Anyone know where I could find a manual? its a 1989 Neusson 5001 RDV, and the engine is a 3cylinder Yanmar with the number 3tn100 stamped on it.
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Before everything went electronic things were a lot simpler.  On my boat and dumper diesels I used to reckon on having only 3 things to check in the event of minor starting difficulties - fuel, compression, air.

You haven't mentioned if you've cleaned the air filter, or tried starting with it removed.  If it is something really simple,that's the 3rd thing you probably need to check.

Patrick

 

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Well, its still not starting. The heater systems works 100%. The compression is good, the air filter is new as are the other filters....it must be fuelling.

The local rumour mill says that the chap I had test the injectors is less than reliable, so I will send them to be reconditioned by a diesel specialist further afield. If it still doesnt work, then its possible the injection pump is worn and not giving enough pressure, but I will cross that bridge if and when it needs crossed, as they are prohibitively expensive to buy new, and used ones are still dear and possibly not much better.

Its rare, but every now and then while working, it will stall. It always restarts straight way without problems, but sometimes, it refuses to accelerate above idle speed. A quick puff of easystart will get it revving up again though.

Will see what the rebuilt injectors do for it.....if not, I have been eyeing up the good 1.7 diesel peugeot engine that I have lying spare, which looks like it would fit with minimal hassles.

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This thing is now officially getting on my nerves.

I had the injectors back last night from the diesel chap. He said there wasnt a massive amount wrong with them, but he gave them a clean and a tweak anyway. Shoved them in and its made no difference. €80 not very well spent - plus I think I paid the "foreigner tax" supplement too.[:@]

It still wont start on its own, and a wee puff of easystart gets it running straight away. If switched off, it will restart within 30 seconds or so. If left for a couple of minutes, its back to needing another puff to get going. However, if you leave it between 30 seconds or so and a couple of minutes, it will start, but chugg over at very low rpm and refuse to accelerate. Again, a tiny sniff of easystart will instantly spring it back to life and accelerate as normal.

The pump is mounted on elongated bolt holes, with a wee scale etched on the edge of the casting, allowing the pump timing to be adjusted. I have tried all possible timing variations, with no benefit.

compression is good.

injectors are good.

filters are new.

pump timing seems fine.

A worn diesel pump is my next thought, but frankly, I have a doubt. If its not getting enough fuel to start or to accelerate when its chugging, what difference does the easystart in the intake make? On a petrol carb-fed engine, I could understand, as the gas would kick the engine over enough to draw in the fuel/air mix, but a mechanical diesel injection system doesnt rely on this to supply the fuel, it is pumped under pressure no matter what. If the pump is worn, why once running does it run perfectly? even at full throttle, full turbo boost and full load, which is where fuel starvation problems should show themselves.

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I am really guessing here but......I suspect the heater plugs, I know you say they are ok but, if it wont start it means there is no heat, easy start is highly volatile and hence, once it fires on easystart there is sufficient heat for compression ignition. This seems to be borne out by the fact that inside 30secs it will restart (sufficient remaining heat) but after it wont as there is insufficient heat.

as I said, pure guesswork. I suggest you re check.

Edit. Just re read what you said about the pre heat system, could there be too much diesel onto the heater element? Its cooling it down too much and hence failing to vapourise? Is it adjustable?

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You need to focus your attention on the crankshaft sensor (it may be on the camshaft drive), its not recognising that the engine is running until it hits over idling speed, the easy start is allowing it to do this without fuelling.

The preheating system will have no effect whatsoever once the engine has started and run for more than one minute, the combustion chambers will be up to temperature to allow compression ignition, the engine will not cool enough in a few minutes to alter this.

That is the reason why diesel engines are so much more efficient than petrol ones during the warm up period and short urban journeys, whereas a petrol engine has to  run at a richer mixture until it is at full operating temperature, once a diesel has started it leans off almost instantly.

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You need to focus your attention on the crankshaft sensor (it may be on the camshaft drive), its not recognising that the engine is running until it hits over idling speed, the easy start is allowing it to do this without fuelling.

The preheating system will have no effect whatsoever once the engine has started and run for more than one minute, the combustion chambers will be up to temperature to allow compression ignition, the engine will not cool enough in a few minutes to alter this.

That is the reason why diesel engines are so much more efficient than petrol ones during the warm up period and short urban journeys, whereas a petrol engine has to  run at a richer mixture until it is at full operating temperature, once a diesel has started it leans off almost instantly.

Thats just the point JR, the OP cant get the initial start therefore its possible (probable?) that the pre-heat system is not in fact working correctly. The heater works, the diesel sprays in but doesn't appear (from here) to vapourise to allow that first kick off. Does this mean too little diesel for pre heat or too much?????

The OP indicates earlier that there is no crankshaft sensor, or thats my interpretation of his comment.

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[quote user="powerdesal"]

The heater works, the diesel sprays in but doesn't appear (from here) to vapourise to allow that first kick off. Does this mean too little diesel for pre heat or too much?????

The OP indicates earlier that there is no crankshaft sensor, or thats my interpretation of his comment.

[/quote]

Yes I too got that impression, but for me that fact that it will refuse to restart when hot after a 3 minute pause rules out the glowplugs 100%

The sensor may in fact be anything that can judge whether the engine is turning but critically above a minimum RPM, I had an XR3i many years ago that had a relay , this sensed the spikes on the 12v caused by the plugs firing, it was intended to cut off the fuel pump if the engine was stalled or not turning, later models have a similar system to protect unburnt fuel contaminating the cat if a car is pushstarted with an ignition fault. Clearly a diesel would use some other way of sensing lacking spark ignition

I reckon Daves digger has a kind of Darwinian protection system intended to prevent muppets from turning over a hot engine with a spanner with the engine run switched on, it relies on the engine being at a minimum cranking speed before releasing fuel to the injectors.

Does your engine crank over slowly Dave?

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It turns over at a decent speed.

There is no crank sensor, and there are no other electronics / electrics related to running the engine at all. Its an entirely mechanical system, the only electrical device is the pre-heat relay and heater element and the stop valve. All of which are fine.

The fault is not with the preheat system because as mentioned above, once the engine has been run, it should start easilly for a good few minutes after stopping without needing to be reheated due to residual heat in the cylinders. Infact, Yanmar engines are renowned for not needing to be preheated unless its the first start on an exceptionally cold morning. The compact tractor I have with a similar 3 cylinder yanmar engine easilly starts without any heating at all, even in winter. Compression alone is enough to get it going.

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There must be something that tells the heater and the thing you mentioned before that dribbles diesel over it whether it is cold enough to engage it, perhaps something has been removed, probably an ambient and/or engine temparature sensor, you did mention a lot of disconnected wiring.

At this point I think that you should start playing and start hot wiring things as I advocated before, start with the engine stop solenoid, hot wire it so it is permanently engaged, stall the engine and try restarting after your 3 minutes.

Then hot wire the cold start circuit to make it work when it is hot and see if it helps,  I know I said that it doesnt need it but try, then disconnect it totally, perhaps it suffers the equivalent of flooding.

When you have found what it takes to make it start you can either search for why the system is not working or working when it shouldnt or you can take a pragmatic view and put a "start switch" in your now permanent hot wire circuit.

Absolute worst case find a cylinder of an easi-start equivalent (try classic racing or aircraft suppliers) and plumb it in with a solenoid and a cold start button.

Good luck! I know it is frustrating but at least you are handy on the tools and not reliant on Monsieur Meccano and his factures to sort it out for you, and also now you know why it was sold!

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No, the heater is manually activated if you decide it needs it by turning the ignition switch counter clockwise for however long you want it to heat before starting.

The disconnected wiring I mentioned has all been accounted for, none of it is engine related (warning beacons, work lights, cabin heating system and similar irrelevant stuff.)

Nothing makes it start, I have tried all combinations of every system. Frankly, its got me completely baffled. If I can find a good, guaranteed injection pump that wont cost me a kidney and a sore botty, then I will swap that out as its the only component left that might be responsible. Untill then, I will just have to keep a few tins of easystart handy.

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I assume that the injectors are manual and driven directly from the pump, that the engine will only start from cold with easi-start and that it will only start on its own less than 3 minutes after running, have I got all that correct?

It now sounds more like a pump problem, not generating enough pressure at cranking speed, I wonder if after it has been running there is residual pressure that allows restarting but bleeds away within 3 minutes?

Could the pump be draining and not able to reprime at cranking speeds? Airleak on the suction side? Diesel filter problem? Water or sludge in the pump or filter?

Food for thought.

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I doubt there is an air leak in the fuel system. If there were, after enough cranking, it would have purged itself and start, but this doesnt happen. There is a manual pump handle to build up fuel pressure in the event of running out of diesel and refilling. Even pumping this up to maximum pressure before starting has no effect.

As to the pump not supplying enough pressure at cranking speed, I dont know. The engine turns over pretty fast on the starter motor, and once it is running it will operate perfectly happily at very low rpm.

I have contacted Yanmar (engine manufacturer) and Neuson (now WhackerNeuson, the digger manufacturer) about a service manual or at the very least engine tech specs, but neither have bothered to even reply to repeated requests.

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  • 2 weeks later...
A little exploring today turned up a service centre about 50km away. The bloke was helpfull and printed me of the relevant exploded diagrams from a live manual. He also suspects the injection pump is worn. When I have the time, I will strip it and see whats what regarding getting it refurbished.

And the real kick in the nads was sitting on his forecourt. A newer version of the same model as mine, with less hours, in slightly better condition, that starts perfectly, and is for sale for 2k less than I bought mine for. Typical.[:@]

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  • 1 month later...
"hello, I dropped off a diesel pump for inspection last week..."

"Hi, yes, we have looked at it and its pretty worn, very probably the cause of your starting problems."

"ok, what now - can you rebuild it or sell me an exchange unit?"

"well, we cant get an exchange unit, you would need to go direct to Yanmar for that, but we can certainly rebuild this one for you, I have made you a quote.....Here it is"

"mmm, pistons, seals, valves, gaskets, labour......€2800. ....€2800!!!! thats...its....wait, what? arrg,, *cough* *gasp* help.... I cant breathe properly, *gasp*  im getting dizzy....."

"will we order in the parts then?"

"erm no. I will be leaving now, thanks."

"ok, that will be €180 for the test and inspection"

*writes cheque with trembling hands, takes his pump in a cardboardbox, drives home and sulks.

I have contacted a few places in UK to see if they will rebuild it for a more sensible price. If not, I will be changing the engine.

[:@]

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If this is the same basic engine as Yanmar supplies for boats, and I suspect it probably is, I suggest you try a company called Marine Power Ltd, based in Southampton and Gosport, UK. They are extremely helpful. In fact one of their guys has his own web site, at http://www.yanmarhelp.com

Another useful company in the UK is E.P. Barrus, of Bicester in Oxfordshire. They are main Yanmar importers, and modify the engines for various markets. They specialise in ground maintenance machines as well as marine, so they would be well worth a try.

Yanmar Europe is based in the Netherlands, see http://www.yanmar.nl/.

Another potentially useful contact is Fenwick, the official French distributor for Yanmar industrial and marine engine spares, www.fenwick.fr .

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Sadly, its not the same engine as the marine ranges, which seem to have much better back-up.

E-mails to Yanmar have all gone completely unanswered, whether written in French, English or German. A brief phone call resulted in being passed from pillar to post by some dis-interested staff with no result.

I have already contacted Fenwic but am awaiting a reply. Perhaps these companies or parts divisions are closed for holidays?

Will contact Barrus tomorrow and see whathey say,

Thanks,

David.

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[quote user="dave21478"]

"Hi, yes, we have looked at it and its pretty worn, very probably the cause of your starting problems."

[:@]
[/quote]

Very probably the cause!!! I would want it signed in his blood that was the exact cause for that money.

What is the point of going to an expert if they can only give you a very probably?

Feelin your pain Dave [:(]

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