glow plug circuit problemo

Discuss (and cuss) the Nissan LD-series OHC Six diesel engine, popularly available in the US in 1981-83 Datsun/Nissan Maxima Sedans & Wagons.

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glenlloyd
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#31

Post by glenlloyd » 15 years ago

Ok, here's the picture of the copper bus bar. The center photo is of the entire bar, the upper and lower images are of sections. This one was bent in pattern to the original aluminum unit but after fashioning the connectors I realized that because it hangs lower than the original, it didn't need to conform to all the curves of the original.

The one pictured is installed on my car, and made out of 6 gauge copper. I'm also going to make one in 4 gauge too, which is harder to work with, but since it doesn't have to conform to the shape of the original it won't matter. Where it hangs now the rod will only need to have one bend in it AFAIK.

Image

sa
97 Jetta TDI, 86 VW Golf D
89 VW Fox diesel, 92 MB 300SD W140

gir - won't the sploding hurt?
zim - silence!

goglio704
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#32

Post by goglio704 » 15 years ago

Are the tabs custom made from flatstock, or did you start with something like a one hole strap?
Matt B.

83 Maxima Sedan, LD28, 5 speed, white, 130k miles. My original Maxima.
83 Maxima Sedan converted from gasser, LD28, 5 speed, 2 tone blue, 230k miles
82 Maxima Sedan, LD28, 3 speed auto, 2 tone Gray/Silver, 140k miles
81 810 Sedan, LD28, 3 speed auto, rust, rust, and more rust!

2005 Jeep Liberty CRD

glenlloyd
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#33

Post by glenlloyd » 15 years ago

goglio704 wrote:Are the tabs custom made from flatstock, or did you start with something like a one hole strap?
I started with a 1/2" copper plumbing strap hanger, cut it in two, rolled the one end into a loop, slipped it over the fluxed rod, then crimped it with pliers. If you get it tight enough it won't fight with you when you solder it.

SA
97 Jetta TDI, 86 VW Golf D
89 VW Fox diesel, 92 MB 300SD W140

gir - won't the sploding hurt?
zim - silence!

Dr. Jones
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#34

Post by Dr. Jones » 14 years ago

Bravo! Hey it ain't no oil scraper, but I think Als right you are going to have to go into business.
'82 Maxima Sedan x2
'92 Saab 9000 Griffin Edition Wrecked
'80 Ford E100(twisted tranny) SCRAPPED

glenlloyd
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#35

Post by glenlloyd » 14 years ago

Dr. Jones wrote:Bravo! Hey it ain't no oil scraper, but I think Als right you are going to have to go into business.
I know...darn, why didn't I come up with the oil scraper! :wink:

I tried to think of a way to do this without the attachments but that would have required 1) finding flatstock that could be bent identically to the original (not fun) or 2) flattening the rod and then boring holes into the flattened section which I felt made it too weak.

I'm working on a couple new ones for my VW 1.6's, which use a lightweight copper strap. It really doesn't need one but I thought I would make it up anyway since I have the materials already.

Steve A
97 Jetta TDI, 86 VW Golf D
89 VW Fox diesel, 92 MB 300SD W140

gir - won't the sploding hurt?
zim - silence!

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asavage
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#36

Post by asavage » 14 years ago

I'll buy two of those at $20 ea. Not because I think I need them, but because they're so nice.
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

glenlloyd
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#37

Post by glenlloyd » 14 years ago

asavage wrote:I'll buy two of those at $20 ea. Not because I think I need them, but because they're so nice.
Super, I'll get on that pronto.

Steve A
97 Jetta TDI, 86 VW Golf D
89 VW Fox diesel, 92 MB 300SD W140

gir - won't the sploding hurt?
zim - silence!

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philip
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#38

Post by philip » 14 years ago

asavage wrote:snip
I am having trouble starting up at "warm start" times. It starts fine cold, it starts fine hot, but if it's sat for 20-30 minutes, it requires a lot of cranking and then I get much smoke. For a test, I jumpered the glow relay with a warm engine for a few seconds, and it fired right up.
snip
Al: This seems about as good a place to ask this question as any ... bear with me. :wink:

Diesels with prechambers usually have compression ratios of 20:1 to 24:1. Anecdotal observations regarding cold starts seems to indicate this chamber design is VERY dependent on glow plug heat to get things going ESPECIALLY as ambient temperatures drop below freezing.

Now ... compare that to the open chamber design.

Open chamber diesels have lower compression (14.5:1 to 17.5:1) and yet are much less dependent on glow plug assistance to get things going. SOME have no glow plugs at all.

Question: With higher compression, WHY is the prechamber design so much more dependent on glow plug heat for cold start-ups?
-Philip
Passed 08May2008
My friend, you are missed . . .

1982 Datsun 720KC SD-22

"Im slow and I'm ahead of you"

davehoos
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#39

Post by davehoos » 14 years ago

the pre chamber is a ball,with a small hole at the bottom.all the fuel is sprayed into this cold chamber.the piston rings would be dry.there is just not enough heat to ignite the rich mixture.i rarely see temps at 0 deg cel[32 F],and have dramas cold starting.to the point of removing pugs and adding oil.

later nissan diesels use a common used system,using an electrical heated[glowplug] with fuel from the return pipe pumped in to the intake.hot vapour..big isuzu engine cold start no glow plugs.old perkins[fordson/fergusen]] engines rarely had glow plugs,some english imports to OZ might have had gas injection,but most of these 12:1 engines relied on decompression lever and fast ree spin to get fuel and oil into the chamber.

the RD28 is a more modern beast,not as long lived but quiet and powerfull.it uses an ingenious glow plug set up that has 3 of the 6 plugs are 12volt,earth through the engine,the other 3 are insulated from the cyl head and earth by relay.this method the plugs are in parrallel for fast glow and series[6 volts] for after start idle control.no dropping resister.

i found a urvan timer,SD23, for a 910 conversion,it rarely worked as the upper limit was around 0 deg.it operated when the ignition was turned on.
the only benfit to me was that it also turned on when cranking,quickly flattening the battery if the engine missed that first start.i end up fitting a push button to operate the glow plug,autralian cars have more switches on the waist mould near the rear demist switch.the lower recess[on the left side of the steering on our RHD cars] is for the fast idle[choke] knob.

however you had to remember to have the car in neutral as it would takeoff when the key was switched on to look at fuel gauges etc.
WCJR31 Skyline.3.0 manual.wagon
R31 SKYLINE/Passage GT/PINTARA
LPG Ford Falcon 99-06 93 Disco
Local Shire Southern Zone Mechanic.

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philip
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#40

Post by philip » 14 years ago

Ohhhhhhkay Dave. :roll: Would you like to take another stab at my question?

Question: With higher compression, WHY is the indirect injection design so much more dependent on glow plug heat for cold start-ups than the direct injection design?

Thanks, Philip
Last edited by philip 14 years ago, edited 1 time in total.
-Philip
Passed 08May2008
My friend, you are missed . . .

1982 Datsun 720KC SD-22

"Im slow and I'm ahead of you"

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asavage
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#41

Post by asavage » 14 years ago

philip wrote:Question: With higher compression, WHY is the indirect injection design so much more dependent on glow plug heat for cold start-ups
than the direct injection design?
In a word, surface area (heat sink). That's my guess.
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

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philip
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#42

Post by philip » 14 years ago

asavage wrote:
philip wrote:Question: With higher compression, WHY is the indirect injection design so much more dependent on glow plug heat for cold start-ups
than the direct injection design?
In a word, surface area (heat sink). That's my guess.
Ok ... but ... in our Indirect Injection SDs, the hottest part of the glow plug is right in the injector's fuel spray. Also, many Direct Injection diesels do not have a glow plug.

Flesh out your thinking a bit. :?
-Philip
Passed 08May2008
My friend, you are missed . . .

1982 Datsun 720KC SD-22

"Im slow and I'm ahead of you"

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asavage
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#43

Post by asavage » 14 years ago

I don't know, how's that?

VW TDis use a GP somewhere, the Cummins B-series use an intake air heater. Some farm equipment don't use either, they're both DI engines.

Maybe someone else knows.
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

glenlloyd
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#44

Post by glenlloyd » 14 years ago

VW TDI's use both coolant system glow plugs and combustion chamber glow plugs, but neither is necessary until the temp falls below 45 F. Farm equipment with DI engine technology without glowplugs typically have ether assist.

I think it has to do with chamber design, or so I've read somewhere, I'll have to dig to see what I can find. The compression ratio however is another story, I've never heard of diesel compression ratio below 19:1. I'll check to see what VW runs for compression on the TDI engine. Without a prechamber it may not be necessary to have 22:1 comp., I just don't know.

sa
97 Jetta TDI, 86 VW Golf D
89 VW Fox diesel, 92 MB 300SD W140

gir - won't the sploding hurt?
zim - silence!

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asavage
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#45

Post by asavage » 14 years ago

glenlloyd wrote:VW TDI's use both coolant system glow plugs and combustion chamber glow plugs
Aren't the coolant system plugs for cabin heat assist in stop-n-go traffic in very cold climes?
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

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