Datsun Roadster Forum-311s.org

I have a 1965 1500 roadster with sealed radiator (no overflow tank). Looking at other roadsters, I do not see many like mine.....my radiator is quite a bit larger and the radiator cap is on top of the radiator....not on the head. Mine began to leak/weep though the top indicating it was not 100 percent sealing at the neck of the radiator. I looked for a replacement in all the usual Datsun sites and could not locate one. After much research I found the Gates model 31527 fit perfectly......$7.91 on Ebay including freight. Thought I would share if anyone else is looking for a replacement cap.

Well done!
It is an easy stealth move to convert the 1500 system to a true sealed system with a pressurized overflow tank.
When it burps out coolant it is able to suck it back in, maintaining the system full of coolant, unlike the stock system which will progressively lose coolant to the outside world.

That cap is rated at 13 pounds. The 1500 should be 4 pounds. It’s not just about the fit. You will push out too much coolant and overheat.

That is a problem indeed!
But if I remember correctly, the SP310 is 7psi.
When I converted mine to a fully sealed coolant recovery system with header tank, I used a cap [Trico CA0750] rated at 7psi to match the system.
https://www.tridon.com.au/includes/imag ... roductHero
That was fitted to the expansion/header tank and a blanking cap [Trico TRC10] fitted to the radiator.
https://www.tridon.com.au/includes/imag ... roductHero
Product listing here: -
https://www.tridon.com.au/products/Trid ... tor-caps#1

Nissan man, the 65 1500 (your car) has the most number of unique parts. If I recall correctly, the three seat cars are lower pressure as Mark indicated. The 65 may be unique for the cap (I think so, but I am not sure). The later cars went higher.

The 63 and 65 Parts Catalogs both call out the same part number 21430-30001, a 7 psi cap. The early 320 truck uses a 4 psi cap that is the same physical size as the 1500 cap. These caps are a different size than the 1600 and 2000 blanking cap.

Might be 7, might be 4, but it’s not 13. One of the most common reasons for a 1500 to overheat is wrong cap. It’s also one of the most overlooked, people start throwing parts at the issue not realizing the pressure matters.

Any chance I can see a picture of your radiator? I have a basket case 64 1500 3 seater BUT it has a R16 motor and 4 speed tranny. I tried to fit the radiator that came with the car but it’s too tall. I purchased a Champion radiator for a 1600 but again too tall. I just noticed that Champion made a small radiator for the 1500 that is about 2” shorter in height and 1” skinnier, it has a 3 row core as well. I was able to swap the 1600 rad with the 1500 rad from with Ledfoot, I’m in SoCal so they aren’t far. I test fitted it quickly last night and it’s definitely a better fit but I need to modify the mounting. Before I started to cut anything I would be very interested on how the stock radiator mounts and what is actually looks like. Most of the pictures and details I’ve seen on the interwebs and 311s.org are for newer models so it’s hard to get a point of reference. Thanks!

Post a picture of the radiator that you have kine8282. One of the 1500 guys on here can ID it for you. If you are having trouble posting the picture, you can email it to me at spl310@hotmail.com

Thanks SPL310. The radiator that came with the car is definitely for an R16. But I am happy to report that the 1500 rad that Champion makes fits with only a few modifications to the mounting holes on the rad cross beams. I’m waiting for a gooseneck thermostat housing as well as the right hoses to come in. The R16 rad hoses that I ordered don’t fit snugly enough for my comfort. They are 1.5” ID and the spouts are 1.3” ID. I know I can clamp it down but I ordered the 1500 hoses to see if they fit better.

Here are some pictures for a 65 1500.
Steve