Daihatsu Dnepr

[johnfireball]

Hi all,
I seek more advice,this time on glowplugs. I am about to do the first test run of my engine & drive train and prepared for starting today. I wired up the glowplugs direct to the battery and gave them 15 secs to get them hot. They are connected in parallel by a bus bar. I was having trouble getting her going due to problems getting the fuel up the feed pipes. I decided to remove one glow plug to test it was heating up ok and connected it across the battery whereupon it glowed red hot and melted. Do all three have to be connected and working together to avoid this or am I missing something? I replaced the broken plug and tried starting again, she was firing on one cylinder and then I flattened the battery. I checked for diesel at the injectors and I reckon its now pumping so hopefully tomorrow.
John.

[smokyjoe]

The glow plugs probably originally were hooked up to a controller that only kept them on for a short time (as in my Volkswagen). The other thing is that they may have been designed in the original application to take into account having a longer run of wire of a smaller gauge going to them which would give them a lower voltage.

Just a guess, but I may be right? I had an air leak problem with my VW where I would have to glow and crank, glow and crank. I burned out a couple of glow plugs in short order.

Good luck!

[andrewaust]

Many glow plugs will have a voltage stamped on the side of the hexagon along with a part number sometimes. You may find they are between 9 and 11 volts, this compensates for voltage drop when activated, depends on the vehicle etc. That might explain the quick meltdown when wired directly. I have a 24V system on my old Nissan, the plugs are 23V, should be a little lower sometimes !

15 seconds wired in parallel should be OK, my old Nissan IDI also glows when I rotate the key to the start position, so I guess you would never want to crank the engine over to long even though voltage drops when cranking.

The old landcruisers used a glow plug in the dash that you could view (still have one on the shelf), probably not good if you chuck your hand under the dash just after glowing either . Simplicity of the good old days.

If you want to turn the engine over and check for atomization etc, pop the plugs out and turn over till all ports are misting. It takes the load off the engine, starter and electrics. Air comes out at high velocity so be careful.

Then pop the plugs in, glow and start at the same time, just remember the 15 sec rule


A;)

[oilburner]

In a parallel circuit the current is divided among the components based on the resistance of each. The voltage is the same for each component, when installed each glow plug on the bus would get approximately 1/3 of the available current. A glow plug would probably burn out more quickly by testing it off the bus for more than a couple seconds. I'd use alternative testing methods.

[johnfireball]

Hi all,
Thanks for the advice, If the plugs get more juice when one burns out doesn't this mean the other 2 will soon follow. I think the metal of the cylinder head draws away the heat so preventing burnout.
Plug resistance 5 ohms : 1/5+1/5+1/5=1/totalohms =1.6 at 12volts= 7 amps
With one plug 5I=12 amps=2.4 So with 3 plugs the the current draw is much the same per plug.
Will have another go today.
Thanks John

[Diesel Dave]

I don't think you can measure the cold resistance and then calculate the current draw.

I'll bet the resistance drops markedly as the plug heats.

You could measure the draw with a meter when actually in use.

It would be a manufacturing folly to have several glowplugs connected in series to create a total load, much the same as christmas tree lights of old if one bulb goes then the whole lot will cease to function. - No start for your car on a frosty morning.

[johnfireball]

Hi all,
Got her running this morning on 2 plugs.Sweet & Smooth, water leak needs attention and seems reluctant to select gears with engine running, will investigate this afternoon.
John.

[johnfireball]

Hi all,
Got everything sorted except getting a lot of blowback through the engine camshaft cover breather. I used a 5w40 fully synthetic diesel oil as I was informed it was the best for the turbo. Is it too thin and causing the problem? I have no manual for this engine and dont know whats reccomended. Perhaps theres a valve in the system, I must check.
John.

[andrewaust]

Nice bike johnfireball, I'm not a lover of full synthetics, guess I'm from the old school , synthetic fortified oil seems OK, I know what you mean regarding the full synthetic oil being thin.

Keep us posted how you go.


A;)

[smokyjoe]

Real nice bike!
andrewaust- So that's what those numbers on the plug flats are! Thanks

johnfireball-
I used to use 5W40 synthetic in my VW, I ran almost all winter (in 10F to 20F weather) without plugging the beast's heater in. I noticed a bit more blowby in the air cleaner than normal (had over 300,000 miles on engine, to be expected) but when using the synthetic in my Hatz 1 cyl. once it warmed up it seemed to sweat oil. It only leaked out the crank seal before I ran the synthetic. I found the breather valve was clogged, but at that time I changed the oil again to 15W40 standard oil, so I am not sure I did the synthetic justice!

I guessed that the leaking all over was caused by the synthetic oil having a better "creep" factor than the mineral, plus it gets thrown all over by the Hatz, having a centrifugal and splash lubrication system.

Good luck and I hope you get that machine on the road soon.

[Stuart]

Looking great there John Just tweaked the code so the other picture showed ok. Nice colour green too

[johnfireball]

Well I suppose I am Irish so flying the flag.
John.

[arnaud]

if you used mineral oil at first, and then synthetic oil, it is not more then logic the engine will leak.
whats worse, all the clogged debris was dissolved by the synthetic oil and sent to all your bearings...