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My Ratsun Datsun 521, now with L-20-B and a five speed


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About a week ago, I put a mechanical oil pressure gauge in Ratsun.  This is how I hooked it up. 

Datsun L-engines have a British Pipe thread in the block.  You need an adapter to convert the British pipe to NPT (USA thread), the adapter is made by Edelmann, number 265220.  Screwed into the adapter is a 1/8 pipe close nipple, and screwed to that is 1/8 pipe "T".   In my case, I used a -4 AN hose to go to the oil pressure gauge, there is a black adapter to go from -4AN to 1/8 pipe.  I had not installed an oil pressure switch in this picture. because the Datsun oil pressure switch threads do not match the 1/8 pipe "T"



This is a GM oil, pressure switch, still in it's box.



This is the switch, It took me a while to get this switch, I ordered it from Amazon.   Most oil pressure switches I found had 1/4 spade electrical connection.  Datsun used a bullet electrical connection.



I just happened to have this oil pressure switch socket, and I used it to tighten the switch in to the pipe  "T".



The switch installed, and the wire hooked up.



Then I turned the key on, and checked the oil light now works.   The camera flash is lighting everything up.



I started the engine, and the light went off.



This is how I routed the hose for the oil pressure gauge.  I do need to get a steering column boot on the firewall.



In the engine bay, the hose goes behind the engine block, just above the transmission, then forward to the adapters, and pipe "T". 



I need to finish the gauge hook up, the light for the oil pressure gauge is not connected, and I need to tighten the hose at the gauge, you can see a drop of oil in the picture above this one.

Edited by DanielC
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You'll notice weird things with a 'real' gauge. Factory ones are weighted just like a gas gauge and don't show the sudden swings. When I was a kid I put a mechanical one on my '64 and was alarmed when braking suddenly the gauge would drop to zero. If it was down a qt. it would sometimes do this on a hard turn.

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Nothing weird about oil pressure changing.  It changes with RPM, and oil temperature.  The oil pressure should fairly closely track with RPM, especially at lower RPM.

Having said that, the oil pressure on this engine (1980 L-20-B, from a 720) does seem a little low. 

Are the oil pumps in a Z20, Z22, or other engine, higher volume and bolt directly on a L-20?


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45 minutes ago, DanielC said:

Nothing weird about oil pressure changing.  It changes with RPM, and oil temperature.  The oil pressure should fairly closely track with RPM, especially at lower RPM.

Having said that, the oil pressure on this engine (1980 L-20-B, from a 720) does seem a little low. 

Are the oil pumps in a Z20, Z22, or other engine, higher volume and bolt directly on a L-20?


Yes, the sell a nice new Hitachi one....

I believe OUP0023..... about $65

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40 minutes ago, Crashtd420 said:

Yes, the sell a nice new Hitachi one....

I believe OUP0023..... about $65


Just got that one from rockauto, HITACHI OUP0023 62.16 shipped.  

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8 hours ago, DanielC said:

Nothing weird about oil pressure changing.  It changes with RPM, and oil temperature.  The oil pressure should fairly closely track with RPM, especially at lower RPM.

Having said that, the oil pressure on this engine (1980 L-20-B, from a 720) does seem a little low. 

Are the oil pumps in a Z20, Z22, or other engine, higher volume and bolt directly on a L-20?



Daniel I meant that compared to the electric gauges like in the cars or 720. They are slow to respond so the owner doesn't freak out. YES indeed the mechanical gauge is fast and it drops down at idle fast also. unnerving to see your oil pressure drop from 60 to 15.


The oil pump from any D21 Hardbody KA engine is a high volume pump. I just grab them off trucks in the wrecking yard. At idle and low RPMs the oil pressure is determined by how fast the pump can replace the oil that bleeds out past the bearings and oil jets. If you replace the pump with one with more volume the pressure will go up. For example my old truck L20B would hot idle at 17 PSI. With no other change but a KA oil pump it went to 28 PSI. The maximum pressure is set by a relief valve so that will be between 50 and 60 PSI no matter what pump you use.


15010-40F00 for the KA24E in the Hardbody

15010-3S500 for the KA24DE


Be sure you know what to look for in a high volume pump. You can't tell from the outside when on a vehicle and you never know what was repackaged and thrown in a box at NAPA or w/e.


Look down into the large hole. Down in there is the top of the rotor.




With the high volume pump the rotor is plainly visible sticking up





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Nice truck man!.....if you go to eBay and type “Datsun 521 truck parts” there’s a few on there right now. As I’ve learned recently there were two different patterns of the “checker” design. I believe they both fit, that doesn’t matter, but the look apparently complements the grill for given years if that makes sense. There’s an early version and of course the later version. I didn’t even realize I had one of each up until recently, but yeah have a look on eBay. 

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How far do I want to get into this.  I have five 521 trucks, and more parts beside that.  When I was much younger, I tended to get into accidents with them, and I kept the damaged truck, and got another one.  This was in the 1970's.  I let the Datsun trucks just sit.

In sometime around  the end of the first decade of this century, I decided to get one of my Datsun 521 trucks running again, the one I call Dragon.   You could still get some parts for 521 trucks from Nissan dealers, they showed up for sale, often for less than $500.00, and you could occasionally find them in junkyards.  I bought Ratsun, the truck this thread is about, for parts for Dragon.

It turned out it was easier to get Ratsun running, and registered before Dragon.


Because I have had 521 trucks for more than five decades, I have had different methods of storing parts for the 521 trucks.  Initially, I tended to try to keep parts from one truck with that truck.   Then I switched to keeping similar parts all in one place.  All parking lights together, all fenders together, all dashboards  together.   You get the Idea.


So with headlight doors, I have had to look in a few different places for the ones I have.  This morning I found the missing left one I need for Ratsun.


I used a rotary wire brush to clean some rust from the back side of the headlight door.



This is a cleaner I use for chrome, I actually heard about it from an episode of Jay Leno's Garage.  This stuff works really good.



I did not take a before picture, but this is after using the Quick-Glo.



I used these new Stainless Steel oval head tapping screws from Ace Hardware to replace the rusted chrome plated OEM screws.



I put the cleaned left headlight door on Ratsun.



This is the front of Ratsun as it sits in June of 2020.





Edited by DanielC
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I have two 521 trucks that are running, Ratsun, this thread is about that truck, and Dragon, it's thread starts here:



I have been focusing on getting Dragon road ready, and registered, and I am currently waiting for Oregon DMV to mail the registration back to me.   I also did some work on three windshield wiper motors and brackets, and swapped painted and working correctly motors and brackets into both Ratsun, and Dragon.  The wiper motor in Dragon did not have high speed, the wiper motor in Ratsun did not park.  I also have a third Dragon green 521, that need a new floor.


Last weekend, I removed three wiper motors off rusty brackets, cleaned motors, removed rust from brackets, primed and painted the brackets, and motors.  This is the one going into Ratsun.



The other two motor and brackets are for my other two trucks.



Third motor and bracket.  This one went into Dragon.



OK, back to Ratsun.  Here is the old wiper motor and bracket that was in Ratsun, the one that did not park.  I got pretty good at just turning the wipers off as the wipers were approaching their parked position.

I have already removed the bolts holding the motor bracket to the cowl.



I disconnected the wiper linkage from the motor crank.



The motor sits very close to the fuse box, I decided to disconnect the negative battery terminal.






I unplugged the connector for the wiper motor wires, and the seperate black ground wire.



This is the plug for the wiper motor that was in Ratsun.



These are the three OEM 50 year old rubber bracket grommets.  above the old ones in the picture are five new grommets, from Ace Hardware.  The sixth grommet is already in another wiper motor bracket, that I took to Ace Hardware, trying different size grommets to fit.



The grommets from Ace Hardware are not as thick as the OEM grommets.  I put one of these rubber washers below and above the Ace Hardware grommet



One of the Ace Hardware grommets on the bracket.



I put grommets on the other two bracket holes.



It may not look like it, but I did clean the area around the cowl where the wiper motor and bracket go.



This is the position of the wiper motor crank when it is parked.



This is a not parked wiper motor crank.  It is easier to remove the wiper motor and bracket from the cowl with the crank in this position.  Turn the wiper motor on, and turn the key off to stop the crank in any position.



I slipped the painted motor and bracket in to the hole,



Then I plugged the motor back in the the harness, ground wire too, and turned the key on.   The motor went to this cranked parked position.



This is the rubber washer, Ace hardware grommet, another rubber washer stack on the bracket bolt.



This is one of the better boots that plug most of the hole for the wiper motor.



I put it in the hole, from inside the cab.  It will slide over the wiper motor crank with the motor bracket bolted down.






Edited by DanielC
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Painted wiper motor installation, continued.

These are the washers, and clip that hold the wiper linkage on the wiper motor crank.



Put the wiper linkage on the crank, and then larger nylon washer.



Then put the thick steel washer on the crank pin.



Here I am holding the thin wavy spring washer on the crank pin.



and then slide the clip that hold the washers and linkage on the motor crank pin.



So, here is the painted wiper motor and bracket in Ratsun, and it now parks.



The next day, I took the park switch cover off the wiper motor that was in Ratsun.



there was more crud in the switch cover.RatWipeMotorCrud2.JPG


The plunger that activates the switch was also stuck, holding the switch in the open position.  

A quick review of wiper motor operation.  The motor is always powered when the key is on.  Turning the windshield wiper switch on the dash on, grounds the motor, and it runs.  The motor can also ground itself, except when the motor crank is in the park position.  

With the switch full of bug crud, the motor could not ground itself, so it stopped immediately when you shut the wipers off, no matter where the windshield wipers were on the windshield.

Edited by DanielC
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When I bought Ratsun, it did not have a windshield washer reservoir, or pump for the fluid.  In one of my trips to Pick-n-Pull, a local junkyard, I got this tank and pump, with bracket from a 720 truck. 



Here is is just sitting in the place I am going to attach it to the inner fender.



This is the bracket the tank slides on to from the top.



I cut a piece of sheet metal to hold the top of the wash tank bracket away from the inner fender, because the inner fender of a 521 is different shaped than a 720.  I cut the side of the sheet metal that is going on the 521 inner fender a bit larger than the two holes in the 521 inner fender that hold the original washer bag and pump.720BracketSupport2.JPG


The other end of the sheet metal I cut to the width of the 720 washer pump bracket.



With the piece of sheet metal cut that will hold the top of the washer tank bracket,  I needed to put two bends in the sheet metal.   This piece of metal was a little too long to bend in a vice directly, so I clamped two longer pieces of 1/2 bar stock on each side of the sheet metal.



Then I clamped the bar stock and sheet metal in the vice.  I could of clamped the bar stock and sheet metal in the vise directly, but it is a little hard to hold everything in place accurately enough, and turn the vise handle.



Then I pushed on the piece of metal, bending it.   I did use both hands, but I had to occupy one hand with a camera, taking this picture.



I wanted to tighten up the bend a little, so I took a block of wood, and hammered the bend a little tighter.



I drilled two holes in the bent part of the sheet metal that will bolt to the inner fender, the holes match the two existing holes that the bracket that the Kangaroo washer fluid bag hangs on.



Then I put the 420 washer tank bracket on the inner fender, under the piece of bent sheet metal, and marked where I want the second bend in the sheet metal.



With the second bend in the support for the top of the tank bracket, I drilled two holes to match the two holes in the top of the 720 washer tank bracket.  I also trimmed a little extra metal off the narrow end of the sheet metal, rounded the corners with a pair of sheet metal snips, and deburred the edges and corners.



I bolted the 720 tank bracket to the top support I made, and then jusr drilled a single hole in the inner fender to match the hole in the bottom of the 720 tank bracket, and bolted that down also.

I also put ends on the wires for the 720 tank motor that match the existing washer motor wires in the 521.



This is a close view of the 720 washer tank motor,



and the plug for the 720 washer motor.



The tank just slides on the bracket.



I ran the wires under the bracket, put the plug on the motor, slid the tank on the bracket, and then ran the hose under the bracket.



I ran the wash hose next to the wiring harness,



and up to the squirt nozzle on the hood.



A quick bit of advise about the squirt nozzle.  It is made of aluminium.  the nut will seize to the threads of the squirt nozzle, and if you try to remove the nut, it very often breaks.

This is a tube of a marine grease I got from a boat dealer, the grease is made by Mercury Marine.



I put a bit of this grease on the threads of the squirt nozzle,



Then I installed the squirt nozzle in the hood.   There is no need to tighten the nut holding the nozzle, it sits on a rubber washer.   jusr tighten the nut enough so the nozzle does not flop around.



I pushed the wash fluid hose on the nozzle.  this is the hose that came with the tank, from the 720 truck.



Fill the tank, TankFill.JPG


and finally, aim the squirter nozzles on to the windshield.   The two nozzles screw in and out of the aluminium nozzle body, and seal with rubber washers.  Again, do not tighten them too tight, they will seize to the nozzle body.



Edited by DanielC
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