720 SD 22 MPG

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.

Moderators: plenzen, Nissan_Ranger

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Gubernaculum
Posts: 9
Joined: 10 years ago
Location: Bryan Texas

720 SD 22 MPG

#1

Post by Gubernaculum »

Bought 1981 720 SD 2 WD reg cab in June 2010 from the original owner. 77k miles.
Have experienced most of the common problems that have been posted on this forum and appreciate all the information:
• DPC not present – had a coat hanger to stop engine.
• Glow plugs.
• Fusible links to glow plugs.
• Suspension problems - ball joints, thrust rod bushings, idler arm, etc.

This is a daily driver and now has 93k miles on it. Starts and runs good and does not smoke. All filters, fluids etc have been changed.

90% of the miles on the open road at 60 mph. My mpg is 28 to 32 mpg using AC. I see others reporting much better mpg than that – 35+ and more!

Should I be getting better mileage?

Marq H.
J M Hellman
81 Datsun 720 2 wd
09 Z71
06 Kubota 5700
04 Yamaha Raptor 660
07 Yamaha Rhino 660
02 Polaris 500 HO Sportsman
07 Lexus ES 350
02 Australian Shepherd
plenzen
Posts: 869
Joined: 14 years ago
Location: Cochrane Alberta Canada

#2

Post by plenzen »

It would appear that you are in the ball park with your mileage. I am in Canada and we have metric measure. I think that you are getting around 7.4L/100Km
(if my math is correct) . That is a bit better than I do with my 87 SD25. I usually get around the 7.8 - 8L/100Km combined driving, and the absolute best I have got is 6.8L/100km on a 700km (435Mile) drive at 90kph (55mph).
Took 47L (12.4USG) to fill.
I know there are guys here that are getting a bit better than you and some that are getting a bit less. My dad bought the truck new and says that it's about as good as it ever was and it has 300,000+ kms (186,000 miles) on it now. He did say that his previous 1985 720/SD22 did a bit better for fuel mileage.
HTH

Paul
Retired Pauly
Problem with being retired is that you never get a day off.
1987 D21-J SD25 KC
KJLGD21FN
greyfoxxca
Posts: 28
Joined: 14 years ago

fuel mileage

#3

Post by greyfoxxca »

well paul that trip at 55 sure was great for fuel mileage. I calculate around 45 mpg imperial.

When I lived in Vancouver I used these little diesel trucks and I had both the mazda and the nissans. They were great for running around town, I moved to southern alberta and every time I start my vehicle I go 20 to 30 kilometers . I found the fuel mileage not that great and the cold winter made it hard to start. I now just drive 3/4 ton trucks and they usually get close to 20 mpg imperial in the summer. In the winter I have a 4x4 jimmy.

If I lived in a big city I would put one of the little diesels back on the road. I have not yet sold them of as I worry about the price of fuel and feel confident that I could become a biodiesel user if needed.

George
plenzen
Posts: 869
Joined: 14 years ago
Location: Cochrane Alberta Canada

#4

Post by plenzen »

Actually it worked out around 42 MPG Imperial ( 35 MPG US ) , still pretty good, but as stated that was the "best" I have done.
I get better mileage in the summer than I do in the winter primarily because of the winter diesel. Not as much energy in it as the heavier summer stuff.
The Co-Op stations around Calgary have started selling their diesel with a label that states. "May Contain Bio-Diesel". I checked on it and they add 5% Bio from May to October and then just go back to the winter diesel October 1. I actually saw a bit of an increase in MPG with the 5% bio over the same summer fuel the year before. The guys at the injection/fuel pump place ( G.C.L. Fuels Systems ) told me that it was OK to use that much with the Stanadyne additive but to check my filters for the first few tank fulls as the Bio is a great cleaner and any crap in the tank etc would be washed out and sent to the filters. They told me that GVT was trying to mandate 3% bio over the year but I guess they figured 5% from May to Oct will work out to 3% over the year.
That was his guess anyway.
He told me that most of the newer manufacturers were OK with a max of 5% without any concern for the newer systems and the ancient ones that I/we have is not an issue but for the older type of seals, hence the Stanadyne additive. Once rebuilt with the newer type seals they should be just fine. Any more than the 5% he suggested another type of additive but I cant recall what it was.

Sorry
I began to ramble

Paul
Retired Pauly
Problem with being retired is that you never get a day off.
1987 D21-J SD25 KC
KJLGD21FN
elminero67
Posts: 143
Joined: 11 years ago

#5

Post by elminero67 »

No-your in the ballpark. I watch mine pretty close and I usually get 30-33. Ive had a few tanks below 30 mpg, and one freak tank near 40 that made no sense. I don't know what it is about fuel milege, but people often exaggerate-or can't do basic math.
greyfoxxca
Posts: 28
Joined: 14 years ago

biodiesel and used veg oil

#6

Post by greyfoxxca »

Well i ran into a guy at the flea market in lethbridge last year who had a nissan diesel rigged up with a extended frame and dual rear tires and a huge box on the back for hauling stuff to flea markets to sell. Well he finally toasted his engine(450k) and bought a real clean 1985 extra cab with the 2.5 diesel (140K) from me.
He burns used veg oil pretty well all the time. I was amazed that he put such large mileage without running into engine problems. He is from edmonton and he runs with the oil after warmup.

We just got a ufa cardlock account and plan on using the bio mixed diesel in our units next summer.

George
Nissan_Ranger
Posts: 267
Joined: 14 years ago
Location: Canada

#7

Post by Nissan_Ranger »

w/b, greyfox; LTNS.....

N_R
The old 'six gun' was as popular as the cell phone in its time and just as annoying when it went off in the Theater.
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5and2dimes1
Posts: 14
Joined: 9 years ago
Location: Lethbridge Alberta Canada

Re: fuel mileage

#8

Post by 5and2dimes1 »

greyfoxxca wrote:well paul that trip at 55 sure was great for fuel mileage. I calculate around 45 mpg imperial.

When I lived in Vancouver I used these little diesel trucks and I had both the mazda and the nissans. They were great for running around town, I moved to southern alberta and every time I start my vehicle I go 20 to 30 kilometers . I found the fuel mileage not that great and the cold winter made it hard to start. I now just drive 3/4 ton trucks and they usually get close to 20 mpg imperial in the summer. In the winter I have a 4x4 jimmy.

If I lived in a big city I would put one of the little diesels back on the road. I have not yet sold them of as I worry about the price of fuel and feel confident that I could become a biodiesel user if needed.

George
Your from Lethbridge? Me too.....

My build thread
http://nissandiesel.dyndns.org/viewtopic.php?t=2370
John
Modsqwad
Posts: 8
Joined: 9 years ago
Location: Victoria BC

Sd 25 VE pump

#9

Post by Modsqwad »

Hi guys, this is my first post on this site. Just bought a 87 d21 with a naturally aspirated sd 25. So far fuel mileage is pretty underwhelming. 170 km on the first half tank. Seems to be hitting on all 4 holes and starting reasonably well in this climate (Victoria 0 Celsius ) so compression can't br too bad. Any thoughts on improving efficiency. I was hopeing to see mid 30's not mid teens. Thanks.
Andy
plenzen
Posts: 869
Joined: 14 years ago
Location: Cochrane Alberta Canada

#10

Post by plenzen »

Welcome aboard.

I guess all the usual places.
Valve set ( 0.014 HOT )
Air Filter
I put synthetic oil in trans ( Red Line MT90) and diff (Red Line 75W90)
Using 5/40 Rotella now for the winter months, 15/40 for warmer times.
Exhaust is OE stock but new(er) Needs a bit of back pressure or you reduce your torque a bit with not much advantage to MPG's
How many K's on it?
Lots of smoke ?
May have to get injectors done.
Use a fuel additive unless the fuel pump has had recent service or you may end up with it leaking a bit. ( Stanadyne or Power Service or Red Line )
I removed the Nissan air box on the left inner fender and adapted a 3 inch PVC inlet that picks up behind the drivers side battery.
That is where I would start.
The fuel gauge is not all that accurate on mine as to what exactly is a 1/2 tank. How many L did you put in after the 170 K's

Paul
Retired Pauly
Problem with being retired is that you never get a day off.
1987 D21-J SD25 KC
KJLGD21FN
Dimitri71
Posts: 3
Joined: 9 years ago
Location: canada

#11

Post by Dimitri71 »

Well mine is a 82 or mostly 82 at least LOL
I highly doubt the heater controll switch on it would be any better than mine LOL
But over all the things I am most looking for are the old u8nder bed tail light assembly's and lenses
I need a overflow bottle that does not have the top half removed LOL
Tailgate would prob be a little expencive to ship that distance though would love to get the rear corners of the box as well as mine look like they have had quite a few bumps lol and I have no clue how you would push out all them dents

I will know better in a few days but I would love a set of injectors if they don't want a ARM and a LEG for them just so that I have to I can get them rebuilt to piut in my engine rather than have to have it go down for a week plus when it is my regular driver

and I definatly though not part of the engine need the flex coupler and rubber piece from the stearing column my is almost broke 2/3 of the way through and haven't been able to find a replacement online yet every time I drive I get nervious turning afraid that last 1/3 will give way I know it isn't safe but no choice as of yet



Heck if they didn't want a exorbant price probably a LOT of little pieces LOL though I would need to know what your going to charge me for doing this for me man as well
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