My 1969 Datsun 521 kingcab

[waynosworld]

I have not had any cool nights lately to test start the engine, when I got up this morning there was a dusting of snow on the truck but it was 36 degrees outside, this evening it got down to 30 degrees and it had not been run today, so I went out and started it, it took off right away but missed a little for around 10 seconds, normally in the past when cold outside(30s) I would have to keep the starter turning while it was trying to start, if I let off it would just die, so I would have to keep the key in the start position till it was actually running which could take up to 5/10 seconds, I expect that is kinda hard on the starter, so I am happy with this "Air Heater Element" so far.

I took a 330 mile trip last Saturday, I drove fairly fast the first half(75/80mph) as I was running behind, coming back I went around 70/75mph, I got right around 30mpg, it was raining pretty hard on the way there, mostly dry on the way back, after about 2300rpms I have to start putting my foot into the pedal pretty deep, that extra 10mph is costly, 2300rpms is about 65mph, 2500rpms is 70mph, and 3000rpms is around 84mph, I spend most my time at 2800rpms on the freeway, the engine ran flawlessly the whole trip, I also had a few people giving me a thumbs up on the freeway, they come up beside me and park there till I look at them.

If it is in the 20s in the morning I will test start it again, I didn't warm it up this evening, I started it, ran it a couple minutes and shut it down.

[waynosworld]

I did a frame notch to this truck last week, if I put even a little weight the axle would hit the frame(no bump stops).
First I put Datsun 720 4wd leafs in the rear, I kept the 2.5" lowering blocks that were already in it, then I did the notch.
First I made a frame brace/stiffener for both sides that would not hit the box above it as I didn't want to cut holes in the box bed.

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Then I removed the box.

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Then I did the notch

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Then I made plates for the sides with holes in them so I could kinda spot weld the whole thing together, then I welded the plates all the way around outside and inside.

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Then I painted and undercoated the notches.

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I then undercoated everything that could be seen from the outside.

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And it is all back together.

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I tore out the complete dash today to upgrade my dash lights so they are adjustable like they were in the 720, I didn't figure out how to do that back in 2010 when I first built this truck, I tested the wiring and all appears good, so now I will apply sound deadening material to the interior firewall and fill/block all holes, I did the windshield the week before and it appears I fixed all the leaks caused by the windshield gasket, I also installed my brand new windshield I had made 7+ years ago.
When I put the dash back in I will be using a freshly powder coated dash face and metal top that has been in storage for as long as the windshield.

[waynosworld]

I fixed the starter bolt today, I took everything apart on the driver side of the engine, drilled the starter mount hole all the way thru the back of the case and I installed a long bolt and put the starter back onto position, it didn't really go all that smoothly as the starter didn't want to go back in, but I finally got it mounted without breaking it.
I also mounted the EGT probe before the turbocharger, I didn't take photos because I just wanted to get it done, the probe is dead center in the hole, and it goes almost the whole way across the exhaust tube, I think it is perfectly mounted.
I also put the air heater element under the throttle body and wired it up, but I didn't use it to start the engine, I just started the engine to see if I had any oil leaks and there are no leaks, but it was dark out so I will check everything again tomorrow, it appears that the blue 90 degree elbow is now rubbing the under side of the hood, I might trim the elbow, but the engine started right up and the starter appears to be working properly with just the 2 bolts holding it in position

It has not been cold since I installed the air heater element in the turbo piping, at least it is not cold enough when I get out of bed, I am still waiting for the mid 20s to test the air heater element.

I worked on this all day and talked to myself several times when things were not going right, but hopefully it is done.

[waynosworld]

Here is the Air Heater Element installed, it's kinda funny, red is ground and black is 12V, it just turned out that way length wise.

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I shaved the blue elbow on one side and twisted the elbow connected to the turbo down which forced the whole assembly lower, I don't think it rubs on the hood anymore, I will know when I drive it again as I cleaned off the elbow where it was black from rubbing on the hood.

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[waynosworld]

I hope everyone is all right.

It never got cold/below freezing for me to truly test this Air Heater Element, but I can say without a doubt my engine starts easier when I use it, when in the 40s if I don't use it the engine misses a few/several times before running smooth(makes white cloud), if I use it it doesn't miss at all or sometimes just 1 or 2 misses(hiccups) and only a puff or two of white smoke.
I have not really done much to this truck lately except drive it, it appears to still have a water leak into the cab, I gutted the interior 2/3 weeks ago, fixed a hole on the driver side floor board and I changed out the dash, I had a fresh powder coated dash face and top, I also put a new windshield/gasket in the truck, it rained but stayed dry, it is wet again, at the time I also changed the wiring so the dash lights are adjustable now, it took me years to figure out how to do that as the 521 dash lights ground out in the dash to work, but the 720 wiring harness doesn't work that way, I used the side maker lights to power the dash lights.

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I have a 411 instrument cluster I wanted to use but I drilled the one in it now for the e-brake and glow plug lights, I have been trying to find little LED indicator lights that look like the ones in it now but have had no luck, they do not look like what I have or they are not as described after they arrived, I am looking for something that looks like the ign/oil indicator lights in the instrument cluster in the photo below.

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[waynosworld]

After years of looking I finally found another 1985/86 Subaru XT turbocharger(used), it sat on a shelf for a very long time, I had to pull it apart and clean everything before it would spin up on my work truck exhaust, the shaft is tight, tighter than the one on my truck now and it works great, I was thinking about putting it on my 720 engine and see if I got the same type result I did on the 521 kingcab.
There is one big difference between the 521 and 720, both are SD25 engines, both have inline injection pumps, but as far as I know the 521 engine injection pump is setup in the stock configuration, but the 720 injection pump has been turned up to run richer, that is what Larry told me when he sold me the SD25 turbodiesel powered Volvo wagon.
These two vehicles are very different driving vehicles, the 720 has a shitload of torque but doesn't really like the freeway, it will go a 100mph, but anything after 55/60mph I have to put my foot in it, while the 521 starts out like it doesn't have a turbocharger(1st/2nd gears) but after it is in 3rd gear it comes alive and it will do 75mph+ using about a 3rd of the pedal, hardly any pedal at all going 60mph, I would be interested in finding out what the 720 drives like with a turned up pump with the Subaru XT turbocharger, but right now I am busy doing other stuff, maybe later this summer as I will have to make stuff to mount it on the 720 engine.

[waynosworld]

It has been a while since posting to this thread, I installed an air heater under the throttle body(carb looking thing) way back but never had the chance to start it in very cold conditions , this morning I got it started using only this heater at 22 degrees, it did not start easy and it took a couple tries but it started, this truck does not never start as easy as my 720 engine does, so I expect next time I will plug in the block heater to help/make it easier to start, it was missing on more than one cylinder sometimes after starting for likely 3 minutes or more(has newer glow plugs in it), this engine has never started as EASY as the 720 engine, but this engine has always been way funner/nicer to drive, it accelerates like a motorcycle while the 720 has a more even acceleration and it does have more torque, Larry said the pump was turned up, both have 3.3 gears in the rear, I do not know what either weighs now, I suspect the 720 kingcab weighs more as it is 16" longer and has a long bed on it while this 521 kingcab has a way lighter/shorter stepside box on it.

I really like this truck since I turbocharged it, if it towed well I would put the 720 diesel engine in my work truck, but the EGTs get too high way too fast when towing so the gas engine is what it needs, 6000lbs minimum of rolling weight(flatbed empty with trailer loaded) is just too much weight for a SD25 engine turbocharged or not, I believe this 521 kingcab SD25 turbocharged engine is putting out around 120hp.

[waynosworld]

I got this trucks diesel engine started when it was 14 degrees, the block warmer was only plugged in for maybe 15 minutes, and I used the air warmer from when I turned it on to warm up the glow plugs, it was ugly when it started that first time(giant white cloud), it did not even try to hit when the block warmer was not plugged in(never even hit), I would never drive it to a place it would totally cool down, I now plug it in an hour before starting it and it starts like a warm sunny day.

This is my favorite truck, unless I am working or I have to haul something(firewood/pavers/cement blocks), I will drive this truck every time, it gets great mileage, it gets 25mpg in the city no matter what, and it gets 30mpg on the freeway going 70mph+, if I could drive 55mph or less I suspect I would get close to 40mpg, maybe more.

[waynosworld]

I appear to have an issue with this truck, a month ago I replaced the stock spin-on fuel filter, it died a half block from my house as I was leaving, I put in a new fuel filter, primed it and it started the easiest I can recall after doing this.

Now if I let it sit for a few days, when I start it, it idles just fine for a minute, but when I start driving it, it starts trying to die like a lack of fuel issue, I saved it by quit trying to drive it and start trying to keep it running and I kept it running and it straightened out, runs normal now.

Normally I drive this truck everyday without an issue, but I put the 1980 Datsun 720 with the SD25 diesel/turbocharger back on the road after 6 years of only starting it and warming it up twice a year, it sat long enough for the drum brake pads to separate from the shoes.

Anyway, does this stumbling issue sound like a Banjo fitting issue on the fuel filter, when I changed the spin on fuel filter I put it on hand tight, I bled all the banjo fittings connected to the fuel filter to get all the air out, I always fill the new fuel filter with diesel before putting it in position, this stumbling issue is new, my pre-filter is a diesel screen not a filter, I always look at that screen and it always looks clean/like new, this only started happening after I started driving the other diesel truck, I need to drive it and make sure it is dependable, it drives good at this time, maybe the Datsun 521 diesel is jealous of the 720 diesel.

[asavage]

I suspect an air leak, the bane of old diesels as fuel lines rot.

It was a huge problem on the Ford IDI diesels of the 80s. The little injector bleed lines would develop tiny cracks, not enough to really leak fuel because those lines aren't ever pressurized, they just bleed a bit of fuel back to the tank or filter, but with the engine off, gravity would try to drain those lines, air would get in, and the filter housing would get a bit of air in it. You could start the truck, but it would shortly die or run rough, until the air in the filter housing would get recycled back to the tank.

The usual troubleshooting method applies: temporarily install clear vinyl fuel line somewhere so you can monitor for air bubbles.

Anyway, that's just a guess from a rando on the internet, take it for what it's worth.

[plenzen]

Are the lines to the fuel filter housing and from the housing to the pump rubber lines.?
I have seen them develop hairline cracks ( from age) and will leak air in and not let fuel drip out. Much the same as what Al was mentioning.
If you remove them and bend them you will may likely see the cracks appear.
Pretty sure they would be hard to find but might be able to get something made as it's low pressure stuff.
If the filter is staying full then I would suggest its the line from the housing to the pump.
Maybe check the banjo fittings like you said or the washers.

I know GM had an issue with the 6.2/6.5 in the 90's with the fuel syphoning back into the tank and had they had little ( one way ) valve on the firewall that the main line fuel supply line fitted to that would prevent that. It solved that problem but not the myriad of other ones they suffered.

[waynosworld]

There is not a lot of room left in this engine compartment, half the lines are between the fender well and the engine, I cannot even see some of them, I did open the banjo fittings on the top of the filter housing to bleed the air out of the top of the filter, I also bled the line between the filter housing and the front of the pump to get as much air out as possible as it ran out of fuel from a plugged fuel filter.

All of them fuel lines get hot where they are at, I suppose some air gets in that area when the truck is driven, likely more air than the starter side gets, any air that gets in there likely had to get thru the radiator.

I will look around, I barely kept it running the time it happened, I did a U-turn and got back to my house, by that time it straightened itself out, it only sat a couple days, it has not happened since, I did not drive it today so far, likely will not drive it tomorrow either, I will see if it happens again.

I do not look forward to replacing them lines, it takes forever to get it started, but I know more now than in the past.

[waynosworld]

Well, I took some time and started this engine to see if I could find an issue, I did find something, the injection pump housing has 4 fittings that the injection lines go to, they lead to the injectors, as the engine was running I looked down and seen what appeared to be fluid on the top of the injection pump around at least one of them fittings, I pulled the air hosen out and blew it clean and it filled right in with new diesel fluid, it appears they are leaking fuel where the fittings screw into the injection pump housing, I could not get to the fittings with a wrench, so I removed the injection lines, used a 7/8" socket and loosened then tightened all 4 of them., put it back together and got it started, it was worse now, so I pulled out an extra not functioning injection pump and removed one of the fittings, all it has is a spring and an O-ring, if I were to guess I would say the O-rings were toast in my engine, one or maybe two leaked before, now it appears they all might leak now , this is just a guess.

Now the non-functioning injection pump was from a forklift engine from Oklahoma I won on ebay, and had shipped to Portland OR, until recently it has not been run by me, I decided to run every engine on my property 6 months ago, this was one of them, I got it running using with the injection pump from an old SD25 engine I over heated and retired for parts as one of the rods was slightly bent and I could not find a rod to replace it, anyway I took one of the fittings off the new injection pump from that forklift engine to see what I was dealing with, a spring and an O-ring, my guess at this time is the O-rings are all shot now after loosening and tightening them all, the original one leaks even worse now, I suspect I was losing more fuel from leaking than fuel I was burning, I have not checked my fuel mileage in a long time, I mostly drive in the city now, not many trips in the last several years.

I also suspect the O-rings are not just cheap O-rings I can buy from the hardware store, since the fittings are not tightened down really hard, I suspect that is the reason for the clamps or they might be referred to as jamb clamps as 2 fittings are held by one bolt, anyway I was thinking about possibly going to the injection services place and buying new O-rings, even though this may not be the issue at all, but I bet I will get better mileage without the leaks.

Has anyone else had this issue?

[asavage]

On the Bosch Inline IP used on the MB OM6xx engines, those delivery valve o-rings are a consumable! It's very common to have to replace them for leakage.

From memory, they're in a counterbore, so you can't over-tighten and squish them. The originals were probably standard neoprene, but you'll want Viton nowadays as neoprene swells in the presence of biodiesel, and BD is in a lot of commercial fuel. In the MB world, they switched the material decades ago so only NOS stock would still be neoprene, but if you were unlucky enough to buy a NOS reseal kit for your Kiki-Diesel IP you might still get the old stuff.

One of those o-rings will allow leak-down of its injector line when the engine isn't running, so that tallies with my "air in the system" and "rotting lines" guess above.

[waynosworld]

On the Bosch Inline IP used on the MB OM6xx engines, those delivery valve o-rings are a consumable! It's very common to have to replace them for leakage.

From memory, they're in a counterbore, so you can't over-tighten and squish them. The originals were probably standard neoprene, but you'll want Viton nowadays as neoprene swells in the presence of biodiesel, and BD is in a lot of commercial fuel. In the MB world, they switched the material decades ago so only NOS stock would still be neoprene, but if you were unlucky enough to buy a NOS reseal kit for your Kiki-Diesel IP you might still get the old stuff.

One of those o-rings will allow leak-down of its injector line when the engine isn't running, so that tallies with my "air in the system" and "rotting lines" guess above.

OK, I want "Viton", I do have that lightly used injection pump that would not start/run the engine on the test stand, the O-ring I looked at looked brand new, I am of a mind to buy new O-rings brand new, there is an injection services place in Portland I have used before, but they are not cheap, I also have a brand new injection pump that I tried to use as in an auto application, but it did not work, I was saving it to put the end of a normal injection pump end onto an injection pump, but this one is an SD25 injection pump, that may have been for an SD22 engine.

I have so many new or rebuilt SD22 injection pumps around here, the one from the forklift engine I was told was only test fired, but it sat in my back room for at least 10 years, I believe the diesel dried out inside the pump and it dried out and the front two injectors were not moving fuel when I turned the starter over.