[Roadsters] 1500 Radiator Cap.

[Graeme S.]

Been through this recently.
My cooling system and engine are all fully reconditioned and I have no 
overheating problem, BUT, it was belching coolant just the same.
Now, bear in mind the early cars were designed for a low pressure 
7psi[50kpa], non-recovery type system.
The cap is not easily converted to a high pressure13psi[90kpa], you have 
to swap the neck of the radiator to get the new cap to work properly.
Low pressure cap uses a long neck, high pressure cap uses a short neck.
All the research I did showed that there is no long neck high pressure 
cap :(
My Radiator Shop advised to retain the low pressure system because that 
was what it is designed for: what the weak link is I know not!
Anyhoo, I decided to fit a blanking cap to the radiator and plumbed in a 
pressurised aluminium recovery tank from the radiator overflow 
connection, using a low pressure long neck recovery cap [7psi], on the tank.
Works a treat and if you didn't look between the front cross member and 
the radiator core, you would never know :)
The system can burp all it wants but it is able to syphon it back in to 
the radiator.
I posted some pics. on the 311s.org site, have a look here: -
http://www.311s.org/phpBB3/viewtopic.php?f=3&t=23012&hilit=recovery+tank
The final version is at the end of the posts.

Regards,
Graeme S.

nissanman.shutterfly.com

On 4/04/2015 09:07, Charles Hubbard via Datsun-roadsters wrote:
>  My 1964 SPL310 (1500)  has run hot since day one. It has a fairly 
> pristine 3-row radiator core.  I live in the Dallas Texas, area, and 
>  it gets pretty hot around here.  The stock idiot gauge steadily pegs 
> on the highway at about 65 mph.  I put an after market gauge in which 
> showed the temperature close to 290 deg.  Slowing down to 55 MPH 
> brings the temperature down but it still runs at 275deg.  After 
> running around town and turning the motor off, it often blows most of 
> the coolant from the upper tank through the overflow tube.  It often 
> vapor locks after it gets turned off.  I took my radiator to the local 
> old school radiator guru today. He did a flow test and it was fine. 
>  However, he noticed that my cap was pretty week.  He thinks my stock 
> cap may only be a 3-4lb cap and suggested that I purchase a 12 lb cap. 
>  .  He's thinking that that my roadster may be continuously be losing 
> coolant when it gets pressurised and allows air into the system, which 
> makes the car run even hotter.  A tighter cap would hold coolant 
> better and help the cooling.  The temperature would stay lower, even 
> under more pressure. The stock radiator caps are not exactly growing 
> on trees, so getting a 12 lb cap to give it a try may not be 
> obtainable.  The radiator shop says they can put a new cap assembly o 
> the unit, but I hate doing that before I even know if it will solve my 
> issue.  Does anyone know a source for a 12lb cap that will fit a 1500 
> radiator?  Feedback from those in the know would be appreciated.
>
> .Charlie Hubbard
> Flower Mound, TX
> cehubbard at verizon.net
>
>
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