How do you cold start an SD-22?

SD diesels were widely available in the US in the 1981-86 Datsun/Nissan 720 pickups, and in Canada through '87 in the D21 pickup.

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Old Smokey
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How do you cold start an SD-22?

#1

Post by Old Smokey »

Ok. You all may be smirking, but I type this in earnest, wondering what the correct cold start procedure is for a 1982 720 KC with the SD-22 motor.

My previous diesels have all been older VWs, which have a cold start knob that advances the timing for a richer starting mix. Simply pull out the knob, start the vehicle, let warm up, then push in.

My "new" 720 has no such knob (or I'm blind), but there is a strange sort of choke that, when pulled, simply moves the accelerator pedal to the floor. Weird. Is this a normal setup for these rigs or do I have a homebrew version? My factory manual is, alas, days away in the mail.

Can someone describe their cold start ritual to minimize strain on the engine?

Thanksamuch,

Andy
1982 720 KC
Old Smokey
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#2

Post by Old Smokey »

Apologies. I should've sifted through the archives first. Finding some good info there, but I wouldn't be offended by a reply either.

Danka,

Andy
1982 720 KC
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asavage
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Re: How do you cold start an SD-22? I'm serious...

#3

Post by asavage »

Old Smokey wrote:My previous diesels have all been older VWs, which have a cold start knob that advances the timing for a richer starting mix.
The old 1.5/1.6l VW diesels have a manual cold start timing advance knob, yes, but it doesn't change the mixture, only the timing. It didn't have much effect on either of the ones I owned ('80 & '82).
My "new" 720 has no such knob (or I'm blind), but there is a strange sort of choke that, when pulled, simply moves the accelerator pedal to the floor.
Well, not to the floor, I hope. It's an idle speed prop. Why it has a butterfly on it, I don't know. Seems like the Universal Ideogram for confusion!
Weird. Is this a normal setup for these rigs or do I have a homebrew version? My factory manual is, alas, days away in the mail.
What about your Owners Manual?
The FSM won't tell you how to start it, nor will it explain the idle prop. But the Owners Manual will. There's one on eBay right now for $12.

I'll let Philip or one of the others give their procedure, or a link to it.
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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Re: How do you cold start an SD-22? I'm serious...

#4

Post by philip »

asavage wrote:What about your Owners Manual?
The FSM won't tell you how to start it, nor will it explain the idle prop. But the Owners Manual will. I'll let Philip or one of the others give their procedure, or a link to it.
Ok, I'll be one of the "...others give their procedure..." :wink:

Obvious it's just a throttle prop. In my case, I rejusted the cable so that when pulled all the way out .... in 5th gear ... the truck will hold along at 57 mph. That's useful!
-Philip
Passed 08May2008
My friend, you are missed . . .

1982 Datsun 720KC SD-22

"Im slow and I'm ahead of you"
Old Smokey
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#5

Post by Old Smokey »

Forgive my ignorance, but what is a throttle prop, what purpose does it serve, and when is it to be used (Philip's cruise control notwithstanding) ?

20 bucks for an owner's manual? Worth it? :?
1982 720 KC
redmondjp
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#6

Post by redmondjp »

Old Smokey wrote:Forgive my ignorance, but what is a throttle prop, what purpose does it serve, and when is it to be used (Philip's cruise control notwithstanding) ?

20 bucks for an owner's manual? Worth it? :?
The 'throttle prop' is nothing more than a manual fast-idle control, which was standard issue on most cars prior to the invention of the automatic choke (my 1941 Chevrolet had two pull knobs on the dash, one with a 'C' for choke and one with a 'T' for throttle). It is used to hold your idle speed at a higher point for the first few minutes after a cold start. Be glad that you have it, as my '81 Rabbit diesel doesn't even have this control (but sorely needs it).

Don't know about $20 for an owner's manual--that's a bit steep. Sometimes you can find one in a junkyard--it's the same for a gasser, so any one from an early 1980s 720 will contain the same information.
1982 Datsun 720 King Cab, SD22, 86K miles (sold)
1981 Rabbit LS 4-door, 1.6D, 130K miles (sold)
1996 Passat TDI 4-door sedan, 197K miles
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asavage
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#7

Post by asavage »

Old Smokey wrote:20 bucks for an owner's manual? Worth it? :?
No, not if you don't need one ;)

From eBay, you can sometimes find OMs for as little as a buck plus shipping, but you have to work the system (ie scan eBay for them often) to get that kind of a deal. Typical price for the 720 and Maxima OMs of that era are $5-10. Right now, there's a 1981 720 OM for .99 + $5 S&H.

Here's a canned eBay search for manuals for 1981-85. It's the one I use weekly to post FSMs to the Peddle forum.
Old Smokey
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#8

Post by Old Smokey »

Thanks for the explanation on the throttle prop. Now, when I pull the throttle prop knob, the accelerator pedal moves to the floor. Is there a reason not to simply use the pedal to maintain a fast idle at cold start? I see no reason for the prop if the same result can be achieved with the pedal. Educate me.
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#9

Post by asavage »

Unattended warmup. Think cold climate in winter. I like about a 15 minute warmup when the windscreen is frosted over. Diesels make too little heat at curb idle to generate enough heat to thaw the windscreen. An elevated idle helps a lot.
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.
Old Smokey
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#10

Post by Old Smokey »

Ahh...of course. Hard to remember frosty glass in the heat of summer.

Unless there's beer in it. 8)
1982 720 KC
1981kingcabsd22
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Re: How do you cold start an SD-22?

#11

Post by 1981kingcabsd22 »

Curiously, my owners manual describes pressing the throttle pedal to the floor after the glow plug light goes out and immediately cranking it. In both warm and cold weather. The throttle control knob appears to be ONLY a cold weather start procedure.
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waynosworld
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Re: How do you cold start an SD-22?

#12

Post by waynosworld »

I only use that knob after I have started the engine as kind of a fast idle so it does not die in really cold temps trying to idle after started, I expect that depends on how fast one has their idle set though.
During the warmer months I never use that knob.
I know the voices are not real,
but they have some really good ideas.
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