My 1969 Datsun 521 kingcab

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waynosworld
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Re: My 1969 Datsun 521 kingcab

#226

Post by waynosworld » 10 months ago

My copper gaskets came today, now I am waiting for the straight rubber turbo piping I ordered as I don't have any more that size.
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I would like to install the heater under the throttle body, I wrote the reason why I am hesitant to do so on NWD, here is a link to the post I wrote.
https://www.nwdatsuns.com/viewtopic.php?p=73730#p73730
I know the voices are not real,
but they have some really good ideas.

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asavage
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Re: My 1969 Datsun 521 kingcab

#227

Post by asavage » 10 months ago

While my opinion is that you're making a lot of effort to overcome a non-issue -- that is, I don't believe difficult cold starting or missing after cold startup is a problem that's to be solved by adding heat to intake air, unless you've lowered the engine's compression -- if a cheap, flexible timer is desired, I bought one last month for a wireless doors control modification that worked our really well, and was about $20 from Amazon. It is not a lot of fun to set up (program) but once past that hurdle it's cheap and extremely flexible. I'm used to buying industrial delay timers that run $150-300, and this tiny critter did what I needed for a fraction of the cost (though, pity the person who has to come behind me and troubleshoot what I did).

I can't access the info on it from home, and I have the day off work, but I'll look it up and post it tomorrow.

[later]

Found it: https://smile.amazon.com/Miniature-cycl ... 015Z2EQCU/ , which is a Amazon reseller of http://timers.shop/Multi-Functional-3V- ... _p_12.html . Get the two-button programmer accessory for $5; it's just two tactile switches on a board, but honestly it's just easier to program this way and worth the $5 to me, even though I have this stuff sitting all over the place. http://timers.shop/Timer-configuration- ... _p_18.html

They've got a manual at their site, and a video. And you need both :( But, again, it's cheap and can be set up to do anything timer related.

If you're driving a typical GP relay, you may or may not want to use a cube relay as an intermediate driver -- I would. Everybody's got a cheap 12v cube relay laying around. If you don't use an intermediate relay, be damned sure to use a snubber diode across the GP relay's input coil. I kinda doubt there's much inductive spike protection built-in to this timer.

--------------------------------------
Years ago, I scanned the entire Electrical section of the 1982 Datsun 720 Pickup Factory Service Manual (FSM), and put it online for reference when discussing this kind of thing. Refer to pages EL41 & EL45 of the 1982 FSM, EL41 GP system schematic:
FSM_1982_EL-041_b.jpg
1982 Datsun 720 FSM, EL41 GP system schematic
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FSM_1982_EL-045_b.jpg
1982 Datsun 720 FSM, EL45 GP system: testing afterglow function
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In that section of the FSM inclusive, the GP controller (located on the right upper kick panel, and for some reason called the After-Glow Timer by Nissan) is shown to control both pre-glow and after-glow functions. Nissan reuses a lot of their diesel technology. On my '83 Sentra diesel, the afterglow relay had failed, and I installed another relay to fix the GPC. Having my own dash indicator to show me what was actually happening at the GP bus -- as opposed to the OEM GP light, which is fun and all but isn't really telling me what the GPs themselves are doing -- helped a lot with that repair.

The OEM GP system is a good design; the wiring and relays, not so much. I know you guys enjoy the fabrication part of owning your trucks, but you might consider doing some diagnosis first.

I checked three FSMs just now (1982, 1982-83, and 1983), and none of them specify the exact time you're to test for:
1982 720 FSM EL45 wrote: " . . . the length of time required to produce the output voltage, when the key is returned from "ON" to "START" . . . " [starter wire is disconnected for this test! ALS]
Without those time specs, it's kinda hard to test, ain't it?

[Paul: I checked the relevant section of the 1985 FSM, and your truck w/SD25 has a completely different afterglow system, involving a dropping resistor and a separate relay; it runs your GPs at a lower voltage constantly for afterglow, instead of cycling them after the engine starts or while cranking or whatever the SD22 after-glow system does.]

I must have given away my Sentra diesel FSM, so I can't check it for after-glow time specs. However, it's clear from the above that the system is supposed to after-glow. In my Sentra, it didn't due to a definite relay failure. It would not surprise me to learn that the after-glow relay in other Nissan diesels of that timeframe suffered similar failures. We know the one in Philip's 720's DPC Module sure did.
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.

waynosworld
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Re: My 1969 Datsun 521 kingcab

#228

Post by waynosworld » 10 months ago

I am kinda playing with this, this truck(my 1969 Datsun 521 kingcab SD25 turbodiesel) does start kinda hard when cold(below 40/45 degrees), just yesterday when it was around 45 degrees it failed to start the first try and I immediately hit the starter again and it continued to run just above an idle(while floored) for a few seconds missing badly, then it started to pick up RPMs and I let off to keep it below 2000rpms, once warmed up it starts easy no matter what the temp is outside, so I am playing with this to see of I can get it started below freezing with this type of heater without plugging it in, it starts great even below freezing if I plug it in for an hour.
The reason I was thinking about a separate timer was to keep the air heater element on for a longer period of time to help with the idle on a cold start up, but I do have the choke cable idle control that these Datsun diesels had from the factory, I just want it to start easier when it is cold outside, and some of you Canadians in central Canada are starting your engines in sub zero conditions with this heater.
I do not have the afterglow option in my early diesel harnesses, I don't have an ECU, and all my injection pumps in vehicles are the inline type at this time.
I suspect I need a new set of slow type glow plugs for this engine, as the 720 engine starts way easier.
I do have a 1985 Nissan 720 SD25 diesel harness(Canadian spec as truck was from Canada) that is different, it didn't have all the usual components, but when I removed the harness I do not recall finding an ECU under the seat, but it has been so long I don't recall much of anything other than it was different, I would have to dig it out and look at it to refresh myself and I don't really see a reason to do that right now.
I am putting the front right hand side floor board/pan and the right side sill/rocker in my Mini right now, focused on that at this time, I am thinking about selling it.
I know the voices are not real,
but they have some really good ideas.

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asavage
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Re: My 1969 Datsun 521 kingcab

#229

Post by asavage » 10 months ago

The Glow Plug Controller (GPC) on the 720 diesel is on the right kick panel, adjacent to the glovebox. See the FSM manual link I posted. It requires its own head temperature sensor, the location of which is shown in the FSM and is right next to the water temp sensor for the dash gauge.

However, there are aftermarket GP controllers too. You have to match your GPC scheme/setup to the type of GPs you're running. The SD25 84-on appears to have used fast-glow GPs (can burn out if left on too long; they are various voltage-rated, like 6v). The GPC for this type of GP runs 12v (nominal) to 6v GPs, which heats them up fast. Faster, that is, than the way GPs worked in almost all other diesels up to that time.

The fast-glow types get hot, fast, then the GPC either turns down the voltage (turn off relay 1/full voltage; turn on relay 2, voltage to the GPs through a big, fat dropping resistor: that's the SD25 system, and my '83 Sentra's system) OR cycles the GPs on and off (ON for two seconds, OFF for five, or similar).

All old MB diesels were the slow GP type for decades, up till around 1980. Same with VW diesels. And the SD22. You could leave the GPs running nearly continuously, and they wouldn't burn out (well, YMMV). But it might take two minutes of pre-glow before you could crank the starter and get the engine to fire.

Once the fast-glow setup was introduced, everybody switched to that system. My '82 GM G30 and my '84 F250 both used the same GPC, with the same afterglow cycling system. A common failure was for it to stick in the ON position and fry all the GPs. It was early tech back then. VW & MB went to the cycling afterglow system and didn't have that problem.

I am guessing you could run either type of GP system on your engines, but the GP and the control scheme have to match.

The intake air heater, AFAICT, was introduced on early DI diesels that have no GPs to aid in starting, and on later diesel engines that needed to be absolutely sure not to cold misfire for emissions reasons. They're not needed for starting, and you're going to need a lot of battery to run the GPs, the intake heater, and the starter all at once.

Think about how Nissan set up the engines for use in all climates. I don't see the intake heater as a necessary improvement, though I'm not saying that it doesn't improve cold idle, but it's not needed for starting. It also draws a lot of amps that you're going to pay to create, it's not free.

If you run SD25 fast-glow GPs, you can't leave them on too long, they'll self-destruct because they're not 12v GPs, they're probably 6v or 8v or similar. I was manually overriding my Sentra's GPC and fried two GPs, twice, by running them 20 seconds instead of the OEM 8 secs. I was trying to overcome a very worn-out engine. I ended up giving away the car, running & driving, because the engine was worn out and the rest of the car wasn't worth another CD17 IMO.

I get the impression that folks want their old diesels to be simple, and they are compared to today's, but they're not 1960s simple. Wiring has to be done. The circuits have to be installed and work. Adding another simply-wired device to avoid doing the hard work of correcting the harder-wired device seems like a wrong turn.

Sorry to harsh your mellow. I just know too much about this stuff.
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.

waynosworld
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Re: My 1969 Datsun 521 kingcab

#230

Post by waynosworld » 10 months ago

I have the slow type glow plugs, I changed them once to a set I bought from Baxters, they worked the best I had ever seen to this day, stone cold that engine roared to life and didn't miss a beat, unfortunately they never worked again because they were the fast type and they burnt out in a system made for the slow type, the ends of all the glow plugs blew up like balloons, I was so lucky to get them out without breaking them, it took vice grips and twisting to get them out, I have never bought another set since and that was 8/9 years ago, I know I have asked for the proper part number and got it from you(Al) I believe, but it was spring/summer and it was starting easy enough so I put it off to the point that I can't remember what thread the number was in, I don't look forward to changing them because it is kinda hard to do as I am not as flexible as I used to be.
I am still going to install that heater on my 521 SD25 diesel truck to see if it will make it easier to start when it is below freezing, I have read too many times about how guys on here start their Nissan diesel engines at 10/20 degrees or cooler, I tried starting one of my trucks when it was around 20 degrees once and it didn't even hit let alone run, the neighbor down the street was also trying to start his Dodge diesel and was having no luck either.
I know the voices are not real,
but they have some really good ideas.

waynosworld
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Re: My 1969 Datsun 521 kingcab

#231

Post by waynosworld » 10 months ago

OK, so this is what I did, first I mounted the Air Heater Element in line between the turbo and the throttle body, I used a cereal box material for gaskets when I mounted the fittings onto the Air Heater Element.
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Then I mounted the relay on the firewall.
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Next I wired the relay to the Air Heater Element and the Battery, I put a 40 amp fuse near the battery.
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I also used the relay plug when I wired the toggle switch to the relay.
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I then ran the wires into the cab(3 of them), one wire is the ground wire for the light telling me when the heater is on, it goes to the ground wire on the relay plug, the next wire goes from the relay plug to the toggle switch, the last wire goes from the toggle switch to a keyed power source, I wired it so when the heater is on the light is on but it is done in the switch, I used the window washer plug in my engine bay harness to power the relay, I did this because that plug has power with one click of the key, it also has power after the second click when the glow plugs also have power, I did it this way so I can warm up the Air Heater Element first, then turn the key one more click to power the glow plugs, then when the glow plug light goes out I can start the engine, then once the engine is running smooth I will turn the Air Heater Element off, the light is fairly bright(red).
The toggle switch and light are in the radio delete plate, the reason I put them there is because I had a radio delete plate with a hole in it for a toggle switch already, I just drilled another hole for the light, I put my good radio delete plate in a storage tub I have for plastic parts.
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I started it once when the relay was wired to the battery and Air Heater Element, it was 43 degrees outside and it started fairly smooth, but I need to start it below freezing to know this is going to actually work this way.
I know the voices are not real,
but they have some really good ideas.

waynosworld
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Re: My 1969 Datsun 521 kingcab

#232

Post by waynosworld » 10 months ago

I started this engine this morning, it was 34 degrees on my property in my back yard in the shade, there was ice on my windshield that was no where near melting and a half hour later it is still frozen, I powered up the Air Heater Element about a minute before powering up the glow plugs, then I cycled the glow plugs twice and then started the engine, it started right up without any issue, it missed a couple times and then ran smooth, I turned the Air Heater Element off right after it was running smooth, it has never started this easy even in the 40s and that block was below freezing as it was 28 degrees last night and the sun had not shined on the truck yet.
It warms up fast when it starts warming up, in the last hour it has warmed up to 41 degrees and the windshield is now melting and the neighbors roof has thawed also, but it was cold when I started it and everything was still frozen.
The Air Heater Element likely would work better under the throttle body as it is closer to the cylinders and the warm air doesn't have to get by/thru the cold throttle body/butterflies, cold turbo tubing to get to the cold intake manifold to get to the cold cylinders, I am positive closer is better, but when I started it today with the Air Heater Element where it is it started when I would not normally even tried to start it without plugging the block warmer an hour earlier as I have tried before in the 30s and could not get it started, this has made a difference for me.
I know the voices are not real,
but they have some really good ideas.

plenzen
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Re: My 1969 Datsun 521 kingcab

#233

Post by plenzen » 10 months ago

Awesome.
Years ago I recall going on a service call with my dad. (Early 60s) up near Prince George BC. and he was trying to get an old Jimmy started. It was about 12F. The ether can that was there (with every Jimmy) was empty. He took the air box off the blower, rolled up a news paper and dipped it in a bit of diesel fuel and lit it on fire. Got a good flame going and had me crank it and he let the flames, smoke, ashes and all get sucked in. It rolled over about 6-8 times and away it went. Warm air is the trick.
Retired Pauly
Problem with being retired is that you never get a day off.
1987 D21-J SD25 KC
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asavage
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Re: My 1969 Datsun 521 kingcab

#234

Post by asavage » 10 months ago

Those old GMCs 2-cycle diesels were completely different tech, and no GPs IIRC. Yeah, external heat + ether was the rule, but the SD series is completely different in almost every respect.
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.

plenzen
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Re: My 1969 Datsun 521 kingcab

#235

Post by plenzen » 10 months ago

I guess the point I was trying to make was getting some hot/warm air into a diesel engine makes a big difference with starting in the cold.
Retired Pauly
Problem with being retired is that you never get a day off.
1987 D21-J SD25 KC
KJLGD21FN

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asavage
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Re: My 1969 Datsun 521 kingcab

#236

Post by asavage » 10 months ago

The point I'm trying to make is that an SD in reasonable condition and with a properly operating GP system doesn't need intake preheating or heating during warmup. Now, that's my opinion, not backed by experience with an SD in a truly cold environment as where you live, Paul. However, I ran SDs for a few years in a climate comparable to Wayne's so I do have apples-to-apples experience, and I did drive an SD on biodiesel, which is notionally harder to light off in cold temps, in 0°C weather many times, and starting was not difficult in the slightest, though cold misfire was reliably an issue for the first minute.

Nissan isn't some fly-by-night diesel manufacturer, they did their homework and while upgrading and modifying is lots of fun and personally satisfying, esp. when applying newer technology and resources not available forty years ago, I think it's helpful to remember that the SD was well capable of starting in below-freezing weather in 1978, without ether or a plumber's torch (both of which were common diesel accessories in the 1950s).

Certainly, supplemental heat was needed to fire up, say, a 6V-71 in 1955 in below-freezing temps and with 400k kms on the clock (reduced compression -> reduced heat of compression available), and that's a DI engine that theoretically is more tolerant of cold temps (no IDI pre-combustion chamber to "rob" heat when cold). But that's 1938 technology, DI, low-compression, and 1.2l per cylinder.

Citing examples of completely different technology from decades before the SD was designed does not build support for intake preheating, IMO. There's a reason why intake preheaters are much more common in the last two decades, and it can be summarized as: emissions. Emissions testing cycles include cold starts and warm-ups, and cold misfire became prohibited because those unburned HC counted against the grams-per-mile limit.

Sorry to sound so aggressive, but this debating about which grid heater is better, seems to me similar to the debates about how adding propane to diesels make them somehow more efficient, or how great it is running WVO directly in a diesel and ignoring the obvious evidence that it both pollutes more than petrodiesel and also ruins injection systems. They're not needed.

It's Wayne's rig, and he's a capable mechanical fabricator. But this is, as are so many modern issues, a problem of electricity. The OEM setup worked fine in 1978. Wayne has cut that electrical system out of his rig and is now trying to add it back in, in a different way, via a grid heater. That's not the approach I would take, and I'll pipe up every so often to remind readers that while modifying is fun, informed modifying is more satisfying in the long run. Nissan wasn't run by idiots back in the SD days, and the trucks & boats & pumps started very well.

If hard cold starting is encountered, the usual suspects should be investigated: cold compression, valve lash, fuel quality, air-in-injection system, fuel restrictions (fuel quality + ambient temps), battery condition (stay above 9.5v while cranking), starter condition (sufficient cranking RPM, likely 150 RPM minimum), correct lubricant viscosity, GPs actually running for correct amount of pre-heat time and actually receiving within 0.5v of battery voltage, injection timing at spec (not guessed-at), and so on.

Or park on a hill and add external heat. Sure, that's the ticket. This seems like a good place to stop.
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.

waynosworld
Posts:519
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Location:Vancouver Washington USA

Re: My 1969 Datsun 521 kingcab

#237

Post by waynosworld » 10 months ago

I am not sure what you mean about me cutting something out of my electrical system, I am running a stock 1981/82 Datsun 720 wiring harness in this truck and everything works properly right down to the glow plug light in the dash, I just added that to my instrument cluster along with an e-brake light, when cold that glow plug light stays on the full amount of time and goes out when the relay clicks(about a minute), while once warmed up it only comes on for a few seconds.

My wiring harnesses in my trucks came with slow to warm up glow plugs, and as far as I know they had no after-glow options the 1981/82 years, they also came with inline injection pumps, basically I made a 720 truck out of my 521 kingcab cab, I used just about every electrical part the 720 had except the 720 heater box motor wiring, I used the 521 heater motor wiring and used the 720 blower motor power wire to supply the power, it's a lot of work to mount that wiring harness and all electrical components into the 521 cab but well worth the result, I even used the 720 column in my 521 to keep the 720 wiring harness stock, I also re-wired my instrument cluster to work the way the 720 instrument cluster worked.

I remember about 10/11 years ago I tried to start my 1982 Datsun 720 SD22 diesel truck when it was 20 something degrees outside, it never even tried to hit/ignite, I never tried starting it again when it was that cold outside without plugging it in, a few days later down the road(3 houses away) a guy with a Dodge diesel had the same issue, his would not start, I had plugged mine in and off I went, his was sitting there the rest of the day, I don't know how he got to work.

I do have a Canadian spec 1985 wiring harness in my inventory, the guy that had it before me did some cutting between the DPC Module and the wire/plug that goes down to injection pump controller, I never really looked at what he had done, he did run WVO in that truck, I just removed the SD25 engine and put it in my 720 replacing the SD22, and I removed that wiring harness and boxed it up and scrapped that truck, that SD25 engine is the one I overheated that has the slightly bent rod, I replaced that engine with the SD25 turbocharged engine in that Volvo Wagon I bought from LarryR that was on here/this forum, that engine ran freaking hot(EGTs) until I figured out how to pipe it as a draw thru, then I figured out the piping out for a blow thru in the 521 kingcab and now all my engines are blow thru as there are no issues piped that way when driven normally.

I am waiting for it to get down into the 20s to see if this "Air Heater Element" is going to work/improve starting at them temps, this engine has never started easily below 40 degrees, it was one of two a crate engines that were bought from Nissan for a 620 and a 521, I ended up with the 620 engine, it had a home made turbocharger setup on it that had the waste gate wired shut, I removed it and drove it without a turbocharger for around 6/7 years, I suspect that engine had less than 50,000 miles on it when I bought it, the other engine in the 521 had a pole building collapse on it from snow build up on the buildings roof, I was told the truck was being rebuilt several years ago, I have never seen this diesel powered 521 truck myself or heard about it being on the road.
I know the voices are not real,
but they have some really good ideas.

plenzen
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Location:Cochrane Alberta Canada

Re: My 1969 Datsun 521 kingcab

#238

Post by plenzen » 9 months ago

Just after I brought my truck back to Alberta from my dads place in Vancouver I had an opportunity to speak to some of the old Nissan techs that worked on the floor of the service dept at a large Nissan dealer here in Calgary. I had a good conversation with them about cold starting issues after my first winter here with the truck. They both advised me at that time that the SD22 in the 720's and the SD25's in the later 720's an the D21's at -10C ( 14F) WOULD NOT START without being plugged in or having a hair dryer or heat gun stuffed into the intake. They were a disaster here in Alberta and Saskatchewan, and anywhere out of the lower mainland in BC from what I recall them saying. Anyplace that got below 20F in fact.

They messed with the coolant temp resistor on the D21 in order to increase "quick glow times" etc and finally just gave up.

There were other IDI type engines here at that time as well and they did not experience the cold start issues that these Nissans did.
Was it pre-cup/ combustion chamber/piston/glow plug/fuel injector design ? Not sure.
The Nissan however did not do very well with cold starting.

To Al's point about engine condition.

Back in 1987 when Dad got the truck and the compression numbers were still at 425lbs (+/-) in Vancouver B.C at sea level, and the temperature rarely got into the mid 20's F there was no problem starting. One cycle of the key and away it would go. After a few years and the numbers started to drop a bit on those rare cold mid 20's F mornings perhaps 2 key cycles were required to start. It was still starting fine in Vancouver, at sea level, with nice heavy, moist, air. 12+ years ago when I got the truck from him, the only thing that had changed was colder ambient temperature, winter humidity in the 20-30 %, and 4600ft above sea level.

All the marine application engines that I dealt with in the 70's in Vancouver had no issues cold starting. They were all manual type push button glow plugs and the rare 20 F day it may be asked to start, usually rarely that cold in an engine room of a boat in 40 F water. and 80% humidity.

I realize that the reference to an old 671 Detroit or even to the 75 Series Nissan ( also a 2 stroke diesel from the 70s ) as far as engine design goes is apples to oranges.
My point, simply, was that pre heating air for an engine that uses compression for ignition is a good thing. That was it, nothing else.

Short of Wayne ( or myself for that matter) putting pistons and liners and doing the head, this grid heater will assist in starting an engine that may not be up to OE compression numbers. Perhaps even obtaining some marine spec glow plugs where you can simply just leave them on may help as well, but the grid heater will help.

Using this grid heater here, for me, where I was told "At -10 IT WILL NOT START" to have it start is a plus.

I get what your saying AL. And did not find your posting "aggressive. "

Wayne:

Have you had a 20 degree F day to try your heater. ?
Did not intend to hijack your posting

Paul
Retired Pauly
Problem with being retired is that you never get a day off.
1987 D21-J SD25 KC
KJLGD21FN

waynosworld
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Re: My 1969 Datsun 521 kingcab

#239

Post by waynosworld » 9 months ago

There have been no cold(below freezing) days since my last post, the low was 39 degrees last night, it has been abnormally warm lately, we had a high of 62 degrees a couple days ago, and it supposed to start raining this coming week, it is called the pineapple express by the weather people, warm and wet, what it becomes east of the Rockies may be something else entirely, some might call it hell.

The engine in my 521 kingcab was a crate engine(one of 2 engines bought at the same time), like I said before mine came out of the 620, this 620 had to have sat around a lot as the body rusted away, the turbocharger waste gate was wired shut so I assumed it was likely a failure, I don't think the truck was driven much so that would mean the engine didn't have a lot of miles on it, after that engine started so easily on my garage floor after laying on it's side in the mud for who knows how long I came to the conclusion that engine had very few miles on it(likely under 50,000 miles), it has however been hard to start when cold outside(below 40/45 degrees), and it won't start below freezing unless plugged in(block heater), I bought this SD25 diesel engine for around $325.00 and it came with a transmission and gauges(pyro/boost/oil temp), I didn't use the gauges as I removed the turbocharger and drove it that way for years, I bought that Subaru XT turbocharger a couple years later and it went on the shelf for years, I wish I had chased that avenue when I bought the turbo, but I likely would have failed as I didn't know much about diesel engines or turbos, I had to learn about them and read all the other peoples turbo failures before I would learn enough to succeed in my turbo conversion, I read a lot of turbo failure threads, I came to the conclusion that almost all of them had to big a turbocharger and they could not build up but a couple pounds of boost, they were all using these large turbos that had to be up at high RPMs before they worked, so I concluded that if I used a gas turbo it had to be a small one to work at lower RPMs.
Then LarryR came into my life, he is a member on here but said goodbye when he sold the car to me, he had that Volvo Wagon with the SD25 engine with propane injection that is in my 720 now, he came over to my house and bought a exhaust manifold from me with the intention of making a turbo manifold out of it, I suggested another way that I read on this forum years before and that is what he did, I would not sell him that home made turbo manifold that had been on my engine when I bought it and to this day I am so happy that I would not sell it as that is on this truck right now and it works great, anyway I tried to make that engine I bought from him run properly but it just ran too hot, it would go over 1400 degrees just trying to get on the freeway, Larry said I drove it wrong, well I guess I did drive it wrong for the way it was set up/piped, it sat for a couple years, every once in a while I would try something new like adding a inter-cooler, different injection pump, all were failures, then I succeeded piping it as a draw thru and fought that 64mph wall I talked about that I was in here asking for suggestions as I had went as far as removing the smoke screw which it doesn't have to this day, then I called and talked to that knucklehead guy on this forum(pretty red engine at the top of the page) as he was selling a rebuilt SD22 turbocharged diesel engine on Craigslist, I asked him how he did it and he told me this very complicated way to do it, I didn't do it his way but he said something about the vent line and a valve and that gave me an idea, I added boost to the vacuum line to make it run richer and the truck pulled hard all the way to red line and it was not running high EGTs, I was likely going near a 100mph when I let off, this gave me another idea, I put the turbocharger on the 521 using that home made turbo manifold and I piped the vent line to a boost source and the rest is history, it has run great since except for when I was trying to use that nice fuel filter made for a gas engine, but I learned other stuff because of that event like how to get a little more HP out of the engine.
I keep talking/repeating myself about this because the more I times write about my success, the more people will likely see it and do it themselves and hopefully succeed, if the correct turbocharger is purchased with the proper seal it will likely work as a draw thru also, but a blow thru setup is the easiest in my opinion, and less likely to have an issue as the years go by, and gas turbochargers are cheap.
I know the voices are not real,
but they have some really good ideas.

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dieseldorf
Posts:190
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Location:Oracle, AZ

Re: My 1969 Datsun 521 kingcab

#240

Post by dieseldorf » 9 months ago

I have a spare LD28 GP unit and after-glow resistor for it, if that would work for you. The plug on the resistor is burnt, so you have to hard wire it. PM me if interested.
Astro Van with LD28 propulsion
'84 Mercedes 190D 2.2L 5-Speed Manual purchased 06/12 SOLD 06/13
'86 Ford Escort Wagon Diesel MT Sold 07-17-08

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