Low oil pressure

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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5and2dimes1
Posts: 14
Joined: 7 years ago
Location: Lethbridge Alberta Canada

Low oil pressure

#1

Post by 5and2dimes1 » 1 year ago

My truck a 1968 Datsun 520 with a sd 22 lost all oil pressure this weekend. I drained the oil and changed the filter but it did not help. The truck starts fine but the idiot light flashes and the gauge reads 0 psi. What could be causing this. Is the engine done or could it be something that is fixable? Thank in advance for your help.

plenzen
Posts: 829
Joined: 11 years ago
Location: Cochrane Alberta Canada

Re: Low oil pressure

#2

Post by plenzen » 1 year ago

Do you have a mechanical oil gauge on the truck ? ( other than the factory installed unit )

I would start by hooking a "KNOWN GOOD" gauge in the spot that the idiot light sender hooks to and read what you get.

It could be a faulty sender unit.

If it's not faulty, and there is minimal or low oil pressure then you would have to remove the oil pan and the oil pump and have a look there. I believe that the pan is removable within the truck, a;though on a 520 I'm not so sure. The availability of an oil pump may be a challenge. You can take the oil pump apart as well and have a look in it and see whats up. Stuck pressure relieve valve, broken spring, or just wore out etc.

If in fact there is no, or real low oil pressure, then how long the engine ran during that time will determine if it's "DONE" or not.

If your concerned about how much damage may have been done you can always take one connecting rod cap off when you have the oil pan off and have a look at the bearing and the journal for how bad it's worn. Maybe even pull the center main bearing cap as well and have a look. They can be put back on and re-torqued ( making sure they go back on the same direction they came off of course ).

Good luck and let us know what you find.
Retired Pauly
Problem with being retired is that you never get a day off.
1987 D21-J SD25 KC
KJLGD21FN

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5and2dimes1
Posts: 14
Joined: 7 years ago
Location: Lethbridge Alberta Canada

Re: Low oil pressure

#3

Post by 5and2dimes1 » 1 year ago

Well don't I feel dumb... I he wire for the oil pressure sensor was off and grounding out on the frame causing it to stall and turn on the dash light. As for the gauge I have it plumbed into the oil supply for the old vacuum pump, and I don't think it is reading properly.

waynosworld
Posts: 417
Joined: 6 years ago
Location: Vancouver Washington USA

Re: Low oil pressure

#4

Post by waynosworld » 1 year ago

I have had all my oil gauges plumbed to that vacuum pump oil source using a "T" except the 720 turbodiesel, they all have worked properly.
The 720 I bought a pancake oil filter adapter with outlets for oil accessories such as gauges as I did not want to deal with trying to get in there to pipe the oil gauge, that adapter would make a good source for a turbocharger oil source also.

So all is good now, I would still be looking for an SD25.
I know the voices are not real,
but they have some really good ideas.

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