Driving an SD25 from Canada - Mexico

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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gregsimms
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Joined: 4 years ago

Driving an SD25 from Canada - Mexico

#1

Post by gregsimms »

I’m starting to plan a long trip with my old 2wd 85 720 from eastern Canada to Mexico. I have about 225000km with minimal mechanical issues on my SD25. What issues have you seen trending with these motors. What SD specific parts would you bring with you?. Am I crazy to thing this thing is capable enough to get me there and back?

Give me your thoughts and opinions!

Thank you
waynosworld
Posts: 571
Joined: 11 years ago
Location: Vancouver Washington USA

Re: Driving an SD25 from Canada - Mexico

#2

Post by waynosworld »

The first real drive I ever took with my 1969 Datsun kingcab with an SD25 diesel was to Los Angeles from the Portland Oregon area and back, the only thing I would think about now is going up the passes, them diesel engines get very hot when going uphill for extended periods of time, they can reach 1400 degrees in a few minutes when even close to being floored even stock, I put an EGT gauge on one of my engines to see how hot it ran without a turbocharger and was very surprised how hot it got, watch your coolant temp gauge, if it starts going up above normal you need to drive slower as the EGT temps are very high.

My only issues are alternators going bad, since I have turbochargers on both my SD25 engines it is a major pain to change the alternators out, and you need a diesel alternator that has the shaft to drive the vacuum pump for the power brake booster, I have went thru 3 or 4 alternators in the last couple years, maybe I need a heat shield for the alternator also.

Have fun on your trip, if you can drive 55/60mph you will get decent fuel mileage(35mpg+), if you drive 70mph you will likely get around 27mpg like I did before the turbocharger.
I know the voices are not real,
but they have some really good ideas.
plenzen
Posts: 891
Joined: 16 years ago
Location: Cochrane Alberta Canada

Re: Driving an SD25 from Canada - Mexico

#3

Post by plenzen »

I have near 400.000Km on my 87 D21 SD25. I would climb in and drive it from Calgary to Mexico, or Nova Scotia, or Alaska tomorrow.
You just cant be in a hurry.
I have taken it to Vancouver BC many times and went over all the different mountain passes between here and there and I just flip the 4 ways on and move to the right as far as I can (paved shoulder at times) to let people go by. There have been a few times I have been right down to 3rd and stay at 70kmh.
(no turbo) I can shift to 4th but it starts to lay down on some of the big hills and rather than dump a bunch of fuel into it and make heat I just use a shorter gear, stay out of the smoke and it's fine.
I stay away from the Coquilhalla Hwy because there is too much UP all at once on that road.
A couple of times last August I opened the windows, put the defrost on high fan and high heat to take some heat away from the motor on a couple of long high altitude pulls locally.
Other than some oil filters and a fuel filter or two that would be all I would take with me.

Paul
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: Driving an SD25 from Canada - Mexico

#4

Post by asavage »

Without looking it up, I think by 1985 the transmission input shaft bearing and front countershaft brgs were upgraded, but I'd still change the transmission oil and make darn sure no chunks are on the drain magnet. No GL5 oil, either, it attacks the brass bits, stick with a full synthetic GL4.
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: 571
Joined: 11 years ago
Location: Vancouver Washington USA

Re: Driving an SD25 from Canada - Mexico

#5

Post by waynosworld »

Staylube makes/sells a GL4 product.
I know the voices are not real,
but they have some really good ideas.
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asavage
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Re: Driving an SD25 from Canada - Mexico

#6

Post by asavage »

I'm an AMSOil man, but any synthetic is better than what was available in 1985 (of course, AMSOil was available in '72!).

The 5-spd transmission was a weak spot, with any of the diesel engines in front of it. That's actually what spurred this sub-forum: when I bought my first 720 on Mercer Island, and it had a stripped input shaft in the trans, due to a failed input shaft bearing. Towed it home, bought a gasser trans, put the diesel front case half on it, and: back in business. That's probably the first post ever in this sub-forum.

Anyway, change the gear lube often on this trans, it'll let you know well in advance if it's getting ready to retire. It never just suddenly breaks.
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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