I took the Ute to my local track in mid December last year for the first time. There was fun to be had, I took it out, what a lot of fun to chase and overtake some newer cars and leave them dumbstruck, the temp gauge stayed at 75-80 degrees Celsius, but mid way into the 4th lap on our 3.267km track I glanced at the temp gauge and saw 110 degrees and abandoned the lap,at one stages I pressed the clutch pedal and the motor died, I coasted down the back straight, let it cool down and drove it back to the pits. Just got to love these Datto motors.

Opened the bonnet and saw the fluid was pushed out. Filled it up and went out again after a hour, same thing just a little faster, probably from driving it harder due to more confidence. Temp goes up, slow down until in pits, check fluid almost out, fill up, out again same thing.

Using Rabbit Radiator and Rabbit expansion bottle. Not sure regarding the pressure rating on the cap of the bottle.

I seriously need help?

Hav ya got the right radiator cap? One type dosent draw the water back in as it cool's

check out the water pump pulley's I have found the odd genuine one that is larger in Diameter and slows the fan/water pump down.. :)

Will measure it, Other thoughts is either the water pump impeller is to far away from the casing or the return line from the Rabbit expansion that goes to the back of the head is incorrect and needs to enter the water flow where the normal bottom hose of the radiator enters the motor.

Never before did I have heat issues, not in town, on a highway or competing in gymkhana. It must have something to do with the prolonged high rpm 5000-7000 use on the track.

Quote:

I'm not sure if this will cause your problem, but you are correct that the plumbing is incorrect. The return from the bottom of the expansion tank needs to go to the lower radiator hose/water pump intake.

The overflow tank serves to collect steam bubbles that may form in the cooling system from cavitation of the water pump or from hot spots in the head. In your situation the bubbles have no where to collect. The expansion of the coolant due to bubbles will push the water out of the overflow tank. In a system setup so the expansion tank is the high point and has flow back to the water pump intake the bubbles can collect and vent if necessary without loosing coolant.

Definitely needs a bigger pulley as the a12 pulley is too small for your needs.

* Datsun 1200 is long shaft, large pulley (spins slower)
* Newer is short shaft with spacer, small pully (spins faster)

I think I hav a brand new one of those long nose pumps, that was mounted to my motor when it was reco'd only to find out after puting in the car it dident match my Pully.. dont hav a pully for it but its free to a good home, Oh and it has a pretty gnarly impeller its folded SSteel insted of a cast thingnot sure if that would be a good thing or not at high RPM??

To fit the large pulley, you may swap the water pump.
They are a matched set:

* positive offset Fan
* short water pump
* aluminum spacer
* larger diameter pulley



OR


* negative offset Fan
* long water pump
* no spacer
* small diameter pulley

Either set will fit into a Datsun 1200.

there is a large diameter pulley with the same stud pattern s early motors..