Just purchased a 1966 Datsun 520

[iota]

Got the odometer fixed - the middle of the 3 vertical gears had popped off the lower one and the "bracket" that holds the number wheels was bent. I shimmed it with a thin washer and it works again.

 

When I get on the gas (like turning into traffic), the truck seems to stumble for a second or two before it really starts to rev up. Doesn't really feel like slipping clutch, guessing it's something with the carb. Not sure if I need to make a new carburetor gasket (didn't replace it when I replaced the carb, just left the old one on the intake manifold) or if I need to mess with the idle screw or what, its almost like it's not getting enough air (or gas?) for a moment and needs to take a breath before it can really go.

[iota]

Took my old radiator (the one that came on the truck, with a broken neck) to a radiator shop. They pressure tested and said it was no good, took it apart to see if there was anything worth saving and said the tanks & the core were all junk. They scrapped it (or I can pay to pick up the disassembled parts but I think I'll pass)

 

The new radiator that I got from 420n620 is working well but has a slight leak in the core - the top side of the bottom tank has a little puddle and theres drip marks under the truck that aren't coming from one of the hoses. I just can't catch a break when it comes to these radiators 🤣

 

Has anyone had any luck adapting a new aluminum radiator to the 520? It looks like the 521 radiators you can get for about a hundred bucks on ebay have their hose connections in the wrong spots, not sure if there is another vehicle that has a similar radiator that would fit (possibly with a custom bracket)

[Crashtd420]

I had good luck with the 3row I bought for my 521, but definitely watch out for the ebay radiators....

Seems you already found the in/out in the wrong spot but also check the diameters of inlet and outlet... make sure they match what you have...

They really like to lump the 520/521 together but the early had the J and the later the L series....

[Charlie69]

Also be sure to make sure the Inlet and outlet are on the correct sides.

[iota]

yeah from what I can see all of the other datsun ones except the Roadster seem to have the inlet/outlets on the wrong side, and the Roadsters seem to have a smaller/more narrow radiator. need to go measure. I've seen some people on here say that VW (possibly from rabbit?) work but I think that's just with engine swaps, need to do more research. open to any and all ideas since these things seem to be getting more and more scarce

[datzenmike]

VW rabbit was for the L16 in the 510. Might fit the L16 in the 521 but not likely the 520, they are small engine compartment and small rads

[gene knight]

check with champion radiators, i know they have a huge selection

[iota]

Got the Datsun inspected yesterday, thanks to Charlie who suggested cleaning the frame rail off with wire brush, it took me quite a while to find the numbers and they did need to see them to issue the title.

 

Radiator is still spitting a little bit from somewhere (not sure if its the core or the bottom tank weld). Old guy in the inspection line ahead of me with a '49 Chevy truck said that there's no good radiator shops in town anymore and that he has had good luck with radiator pellets (stop leak). Anyone try those? I just get a couple drips a day under the truck, haven't had to add any coolant at all so its an extremely slow drip.

 

The engine still has hesitation when you really get on the throttle (pulling out of a parking lot), which I'm guessing is something with the carburetor but not sure what. I think I'll take the carb off and make a new gasket as the old one is probably junk.

 

Otherwise she's running great and will be going to cruise in soon! can't wait!

[Charlie69]

So Iam guessing you passed the inspection.  Great news you are legal! You can try a good radiator sealer.  Just remeber you need to drive it and get it warm and circulate it though your system.  I usually will remove the thermostat before adding the sealer and replace the thermostat after it has been well heated and circulated.  I always run the Thermostats with the jiggler bypass built into them.

 

http://www.stant.com/files/6714/0979/6576/Offset_Thermostat_Instructions1.pdf

[iota]

Passed inspection, so happy about that! Finally going to get my title, will only have taken 7 months 🤣

 

A couple days ago I decided to say "screw it" and I put in half a package (3 tablets, crushed up) of Bar's Leak radiator tablets, the kind that American cars come with from the factory. I then drove around for 30 minutes. When I got home, the rad was bone dry and the faint drops/smell of coolant I had expected were gone. No drops on the floor since. Problem solved (for now)

[datzenmike]

Have never heard that urban myth about American cars with it from the factory.  Genius sales pitch on their part. I've heard of using egg white, condensed milk and even pepper to plug a rad leak. Does it say to empty out once the leak is sealed?  

[iota]

Yeah the tablets are GM part #12378255, adding them was part of the routine maintenance back in the day. Probably due to the "high quality" of the American made cooling systems 🤣

 

It's just a powder pressed into a tablet shape that you dump in and circulate through the system; I think it works by hardening once wet and exposed to air, so it doesn't need to be flushed. If I ever do pull the radiator or replace it I'll flush the entire system again just to be safe but I figure that it's fine for now. I would guess it will burn off or evaporate eventually, and I only put in half the recommended amount so I'm not sweating it. No drips on the garage floor today still so I am pleased.

 

I also added a Dorman 54002 coolant catch tank so I wouldn't end up with drops from the overflow tube going onto the ground. Looks kinda clunky in the engine bay because it's so big, clean, and white (everything else is dirty!) but it should work fine.

 

thanks again to everyone here for the advice on getting this thing running. I think we will just enjoy it for the summer and then maybe once cruise-in season is over in the fall I'll replace the head gasket and give it a really good once over (still has visible, but not excessive, white in the exhaust and hesitation sometimes when really getting on the throttle)

[datzenmike]

The GM part probably isn't Bar's Leaks but their own.

 

Overflow can? Did you get the special coolant recovery rad cap to go with it? It allows water out but when the system cools down a second valve inside the cap opens inward and the coolant siphons back in. I used to add a cup every month but now the rad is topped up every time I check and the losses are almost zero per year.

[iota]

Nah I am still using the original cap on this rad which is just a one-way one - it will spit coolant out into the bottle, and then periodically I'll pour it back in the rad. I just wanted to be able to capture any excess that comes out so i could know for sure that any drips or drops on the garage floor (cardboard) came from the radiator itself, not just from hot boil off. Plus its better for the environment so that's good

[datzenmike]

Only a few bucks and it works perfectly. Rad is always topped up. I used to run it several cups low to prevent it spitting out but with the coolant recovery it's always right at the bottom of the rad cap full.

[iota]

Nice do you happen to have a part # or a link to the proper rad cap for the 520 that can siphon back from the recovery tank?

[datzenmike]

The 620 after '77? had a recovery tank and all after '80 vehicles did but also layer the rads got thinner and the caps smaller. So '80-'83 200sx, early 280zx, 810

 

The Nissan number looks like 21430-C0500 but just ask at NAPA for a coolant recovery rad cap for a 620. They look like this...

 

[iota]

Long time no updates. Truck hasn't been driven much recently but when we have driven it, it's run pretty well.

 

We recently took out the metal dash cap (which was faded, rusted, and peeling really badly) and sanded it down to bare metal and repainted it with John Deere Blitz Black paint. Turned out really well, now i need to figure out how to get the lid of the ashtray off without destroying it so that I can paint it to match.

 

Also took the Datsun to the cruise in at a nearby parking lot yesterday and it got more attention that most of the muscle cars, which was pretty funny. Always seemed to have a little group of people milling around and peeking inside at it, whereas the supercharged NSX next to it didn't get much attention at all.

 

I noticed while following my wife home that the brake lights don't seem to come on under light braking, but I know they work if you really step on the pedal because I have tested them multiple times before inspection. I checked the wiring (unplugged from the hydraulic switch and shorted them, lights work fine). I'm not sure if the brake light switch is just worn out or if it's just an issue due to converting to front discs (so the pedal doesn't go as far before you're really stopping), but I ordered another hydraulic brake light switch from rockauto and will try that soon.

 

Edited July 22, 2020 by iota

[wayno]

I you want to get rid of the pressure switch you can put a switch from a 720 or anything else and mount it where most switches are mounted in 80s vehicles where the pedal arm actives the switch, this is what I did in my 1966 Datsun 520, but I am using a 1980 Datsun 720 wiring harness, you would just need to make a couple wires that go from the pressure switch to the new switch inside the cab.

[iota]

Good idea, I might try that if the pressure switch proves to be too much of a pain to get working right

[Charlie69]

Enjoy your little truck.

[XXL]

On 7/22/2020 at 1:07 PM, wayno said:

I you want to get rid of the pressure switch you can put a switch from a 720 or anything else and mount it where most switches are mounted in 80s vehicles where the pedal arm actives the switch, this is what I did in my 1966 Datsun 520, but I am using a 1980 Datsun 720 wiring harness, you would just need to make a couple wires that go from the pressure switch to the new switch inside the cab.

 

I did this a few years ago to solve the 'light pedal press' problem. Datsun also realized the error of their ways and dumped the hydraulic switch in favor of mechanical one in late '68 or early '69. My late '68 520 (May production) came with hydraulic but also already had the bracket over the brake arm (just didn't have a switch in it). Try to get an all metal switch as they tend to fare better than the plastic ones. My go-to part is a mid-1980's Volvo switch (I use the same part on several of my assorted vehicles). All the GM or 'universal or Ford ones I've unboxed at the parts house are plastic. Volvos, metal.

 

I have had to occasionally adjust the switch position as the brake shoes wear and the pedal sags as a result... maybe once per year. Easy peasy two minute task 

 

Also, nice looking 520 you got.

 

 

[wayno]

My 1971 Datsun 521 still had the pressure switch for the brakes, but as I recall I switched over to the pedal switch when I put power front disc brakes with dual brake circuits.

[iota]

Anyone know the right size/thread pitch for a bolt to fill the hole that the pressure switch comes out of? After reading some reviews of the hydraulic pressure switches on Amazon and most of them say "worked great until it leaked and I lost the ability to brake while driving" I am thinking that just switching to mechanical is the way to go instead of messing with replacing the pressure switch.

 

@wayno, what did you use for that bracket to hold the mechanical switch? I see the mechanical switch in stock in a lot of places but trying to figure out the bracket without too much fabricating

[wayno]

I think I just made that bracket out of some scrap metal, I have all sorts of metal brackets around here in a 5 gallon bucket, I save everything, that is also my achilles heel, I have way too my stuff like that around here, I had to build a shed to hold it all.