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The 2000 and 1600 cooling system is pressurized and depends on water pump circulation as well an efficient fan cooled radiator and a properly functioning thermostat. Total capacity of cooling water for the 2000s is 8.5 liters or 2.245 US Gallons. Total capacity of cooling water for the 1600s is 8 liters or 2.11 US Gallons. The 2000 stock thermostat begins to open at 179.6 degrees fahrenheit plus or minus 3 degrees. The thermostat should be fully opened at 203 degrees fahrenheit plus or minus 3 degrees. The 1600 stock thermostat begins to open at 162 degrees fahrenheit plus or minus 3 degrees. The thermostat should be fully opened at 176 degrees fahrenheit plus or minus 3 degrees. Part numbers for thermostats Stant 160-xxxxxxx or 180-xxxxxx. I will get these soon.

Overheating can be caused by several things. A check list follows:

  • One of the simple overlooked ones can be a loose fan belt.
  • Excessive carbon deposits in the cylinders(Here is a plug for Chevron-I run their Premium. All of their gas has the Techron additive that many a mechanic swears by.)
  • Running the ignition too far retarded.
  • Incorrect carburetor adjustment-lean mixture.
  • Loss of water due to a blown headgasket.
  • Bad water pump.
  • Clogged radiator.
  • High compression due to shaved head.
  • Non-functioning thermostat--improperly installed thermostat.
  • Too much anti-freeze- 40% is recommended.

General cooling system maintenance should consist of checking and tightening the fan belt on a regular basis i.e every 1,000 miles. Check the hoses for any undo wear. A yearly flushing is another good thing you can do for the cooling system. Anitfreeze does not last forever and if you counted all the times you topped off you might be surprised at how diluted your mix has become. Never run just straight water unless it is a full time race car. They use an additive such as water wetter. On a street car 40 anti-freeze/60 water is good for general purposes. Water pump bearings do not like just plain old water as the anitfreeze provides a lubricant. A little preventive maintenance can go a long ways.

On the 1600s there are two types of thermostat housings-the early cars had three bolts mounting the tower on. The later cars have two bolts. The two bolt is a prime candidate for a L-series 16,18,20 or Z car through '78 inlet(gooseneck) replacing the tower completely. 240Z gooseneck Nissan Part # 11060-U0100---$11.00 (approx.) Local dealer item. You may have to drill out the mounting holes on the gooseneck a bit to get it to line up with the holes in the head. This creates a problem as to how to get fluid into the cooling system. There are two ways to tackle this. One would be to replace the 1600 radiator with a 2000 radiator. If you use a 2 liter radiator you may need a new pitcock valve---Drain Cock HELP! Part #61114, price(Forgot...), Advance Auto, Pep Boys, or Kragen- (UPC 3749561114) any part store should be able to look it up with that number. Look in the section that sells extra door handles ect. The upper curved radiator hose Part # (D) 70806 CS (UPC 3824470806), Advance Auto Parts. This hose is too long but all you have to do is line it up and cut off the excess. Couple of seconds on the band saw. The second option requires you to modify the 1600 radiator by having a filler similiar to the 2 liter radiator fitted. Here is a picture with the fill cap on top of the radiator. The owner reports it clears the hood but barely.

Click here for a larger view. Either way will work just fine.

Removal of the 1600 thermostat housing can be a bit challenging. I usually pull the top part off that the cap fits on. The studs are normally fused together with rust to the housing. PB Blaster is great stuff for breaking up rust. Shoot copious amounts on on the bolts-let it sit for awhile. Come back and gently begin tapping with a rubber mallet. I have removed several housings with this method not breaking anything. Patience is a true virtue. Buy some if you do not have any-you will need it in other areas as well. When putting the housing back on use a dab of anti-sieze on the bolts to assist in removal later on down the road. I believe some one used stainless steel bolts instead of the old steel bolts. It could be worth trying.

Take care of the little car and it will give you a lot of enjoyment for your efforts.