Hi guys.
Need some expertise.
When I drive my 1200GX in town, even with lots of traffic light stops, the temp guage lies between cold line and the middle line.
When I drive at a constant speed of 120km/h on the highway it lies between middle line and the hot line on temp guage.
I did this test 2 times on the highway with different outside temperatures.
My radiator is a double core.
I took it to be cleaned up at a radiator shop.
And then did the second test with no better results.
My termostat was also tested 6 months ago.
It is the correct temp termostat and works fine.
Dodgeman suggested I put in a tripple core.
Thanks for the advice dodgeman.
I am just posting this to hear if somebody out there did'nt experience the same problem. If yes, what did you do to solve the problem?
I am thinking of doing the triple core change.

Something that I can also mention is that the plate underneath the engine has been removed.(I think it is the sump cover).
Must I put it back or will it not have any effect.I heard that someone told me it helps with the airflow.
Thanks

For a Datsun 1200, that is the normal temperature reading (between 3/4 and the H mark) [edit: at least on mine]. It shouldn't hurt the engine.

I have trouble believing this is the normal running temp on the freeway. Get a good original radiator and try again. I used to be able to run at 120kmh for hours with the original A12 (on unleaded) and it would get up to 1/2 at the most. I think your radiator is buggered, and the radiator cleaning people didn't do a good enough job.

Is it also possible that you are running a bit lean on the carby main jets? Have you had it on a dyno, especially if you've made compression/cam/carby changes.

I know that going from leaded petrol to unleaded petrol will raise the temperature a bit also at freeway speeds.

Chris

Is the motor definately running hot?
My point is - - could it be the temp guage playing up for some reason. I'd check it with a temp guage that actually shows coolant temperature.
If you pull over after a run on the highway is it overheating?
Just some more thoughts that may help you before you go and spend a heap of $$$ for no reason.

Happy New year.
I've been driving a 210 with a A15 engine for almost 15 years and have never seen the temp gauge past 2/3. It could be your water pump belt is slipping at high speeds or something with the water pump. But the radiator does seem the most likely.
Good Luck

does your radiator have a fan shroud, sounds as if lack of air flow through radiator at higher speeds air being sucked around radiator or under car my car ran slightly hotter at highway speeds but always around the 1/2 mark
Bob

good point bob. Also if the new radiator doesn't sit flush on the old radiator front panel, then the gaps must be filled to ensure that the air goes through the radiator. I've seen many intercooler installations cause the radiator to stop working, just because the air would prefer to go around the radiator, rather than go through it.

Chris

Hi Guys.
Thanks for your comment.
Here is some more information that I can give you.
There has been no modifications done to the engine.Stock standard 1200GX motor.
When I took the radiator to the shop, and got it back they showed me what came out of the core.A handfull of rust and dirt.I think they acid bathed it to clean all the stuff out of the radiator pipes.My radiator is also the genuine radiator that the car came out with.
No holes that the airflow can get out of.I have checked that also.
Also when I came home after this hot run it did drop slightly on the temp as I started to drive in town on my way home.
I checked the water.It was still fine.
Level was still the same and did'nt boil or anything.I still even use the 4 blade engine mounted fan.That is suppose to help with sucking air through.Right?
I have checked wreckers for another radiator.What they ask I might as well do the triple core conversion as the price they are asking me is about the same.The belt on the pump is also fine.No slipping.
Are you guys also using double cores?
And temp only going to halfway with it?
I must mention. That the temp when I did this tests was about 30 to 32 degrees celsius outside.It gets a bit hot here.Maybe the radiator is not up to the job with our temp here.I may be wrong.
I want to drive my car highway on vacations to nearby places.Enjoy driving my datsun and it is good on fuel economy.
But not when it is doing this.
Please help.

I was going to ask what the ambient temp was when this happens, but you've got that in your last post. I live in QLD Australia, where the summers are always above 30C, and it has always been my experience with A series 1200s that the standard cooling system just isn't up to the job on the highway in summer. 120Ys (210) and Sunnys (310) don't have the problem.

I bet you'll find the temp runs fine if you stay under 60mph on the highway, but just keeps slowly but steadily increasing if you hold a continuous speed above 60mph on a hot day.

It basically comes down to the fact that the radiator simply isn't big enough for the job in hot climates. You're better off getting a radiator with a larger core area than a triple row - much more efficient. It doesn't need to be much bigger. I think I used a Sunny (310) radiator. Not sure what you guys got in SA, but basically any radiator from a later model Datsun that had an A series motor will have a larger radiator - seems like Datsun knew it wasn't up to the job as well...

You are 100% correct.
When driving at 100km/h it lies just beneath the middle mark.
When driving at 120km/h it gradually rises to 3/4 on the gauge.
And yes, we are getting similar temperatures here in SA as you there.
Sometimes we get 35 degrees celsius.
Maybe I must do the test in the night when we get in the region of 17 degrees celsius or in the winter and see what happens.
I will start to look out for a 120Y radiator.
Must I modify something to make it fit or will it just bolt in. Any help or advice is appreciated.