Get a gemini radiator...$55 for a flushed and sprayed one with 3 months exchange if the thing is crap. You will also be able to use your current hoses....

So all this happened after you put a new second hand radiator. If thats the only change you have done and this is the result, then this is the problem. Maybe the radiator is blocked? But firstly do you have the right radiator cap and is it sealing? If the coolant isnt under pressure, it will boil at a lower temp.

Sounds like you need a new mechanic

Anyways, it's very easy to test the radiator flow:
1. When engine is cold, drain all the coolant from the radiator
2. remove the bottom hose from the radiator
3. Cover the bottom outlet with your palm, and fill the radiator with plain water from a hose
4. When radiator is full, quickly remove your palm
- If the water gushes out the same amount as the bottom outlet, that's a good sign
- If the water trickles out, or runs out but in a stream smaller than the size of the outlet, the radiator is partially plugged

This happened to me. The radiator didn't look plugged, but it was. This can cause the suction hose to collapse as well, since the pump is on one side and a restriction on the other.

ok i have 2 things 2 ask, i have checked everythin but then these 2 popped up!!!:
When i take my cap of and rev the engine the coolant seems 2 drop right down 2 the cores. I was old 2 buy a new radiator cap with a rubber seal and an overflow bottle???, is this worth doing??

Also i still have the stock 4 speed and diff runnin on the a15, could it be the engine is workin to hard???

Tommy

Right!!
I will go try this now!! I mean as they say you cant tell a book by its cover so i spose this goes with cars aswell, the radiator looks fine (with a few snaps in the bars) but of course as you say it could be internal...
Tommy, are you still having overheating problems with your car even tho your radiator, head and water are all fine??

My god this post has gone on longer than expected and had more response than i once thought!! Cheers guys!! Its good to know that the 'oldies' do help out the new Datsun owners/fans!!

Thanks
Dave

Radiator specialists normally do a free cooling system check if that interests you

Quote: This is simply a conversion to a coolant recovery system & i did it in my 1000 sedan. It prevented gradual coolant loss by catching it & returning it to the radiator when it cooled down, & it allowed me to monitor coolant level, hot or cold, without lifting the cap. I like this system, & will be fitting it in my 1000 coupe.
It works for me.

A coolant recovery system is a good thing, but you don't need one. Indeed, 1200s did not come with one. A15s do not need one either. Unless you are using a near-boiling-point thermostat, which is not recommended.

Without it your engine should still cool properly. The question here is, when your engine overheats, is the coolant level low? Say you fill up the radiator, then drive it for a while, when it gets hot (before it boils over) stop the engine, let it cool down, then check the coolant level. If it is still full, the problem is not a bad cap. On the other hand if it is low, it's leaking out somewhere. The cap seal could be bad, a hose clamp could be leaking, it could be pulled into the cylinders (bad head gasket), etc. A pressure test is called for, which any shop can do. Also I would do a compression test just in case. Stop guessing and buying parts you may not need, and start measuring ...