My Fiat 124 Thermostat Goes Which Way?!

From Matt,

First things first, if you have a unit that looks like the one pictured above, then the tube on the left side of the picture is the one that goes to the lower radiator tube.

However, regularly, we get calls that a thermostat is bad out of the box.  99% of the time this is not true! The fact is, the Fiat 124 coolant system is hard to fill correctly, since the high point is the hose above the back of the cylinder head.

At Vick Auto, we have the fix.  A coolant burp/flush kit for Fiat 124 (Spider, Coupe, etc.) is the best answer to the pesky air bubble issue in a Fiat 124.

As you can see in the picture, the burp/flush kit is easily installed in the upper heater hose that passes over the exhaust cam. At Vick Auto, we try to have these in stock at all times as it is the best way to get rid of air in the coolant system.  Our instructions for filling your coolant system with one of these kits are as follows…

  1. Install burp/flush kit
  2. Open heater valve to ensure coolant fills the heater core
  3. With the caps off of the burp/flush kit AND the radiator, begin filling the system from the radiator cap
  4. Once you can no longer fill into the radiator directly, move to the burp kit cap and begin filling from there. DO NOT PUT THE CAP ON THE RADIATOR, YET
  5. You will see bubbles and some fluid poor out of the radiator, this is to be expected.  Once the bubbles stop, put the cap on the radiator. DO NOT CAP THE burp kit
  6. Fill more into the burp kit while slowly and gently squeezing the upper radiator hoses. This is to help suck fluid into the cylinder head
  7. When no more fluid can go into the burp kit, place the cap on it
  8. Now that all the caps are in place squeeze the lower radiator to thermostat hose rapidly and hard about a dozen times. This is to disperse and clear out any air bubbles at the thermostat or just in the lower motor
  9. Open the cap on the burp kit once again you may see it is empty, that is to be expected.  Simply fill it up until it can take no more while gently squeezing the upper radiator hoses
  10. You should almost be done!  DO NOT GO FOR A JOY RIDE YET
  11. Start your car and let it reach operating temperature to ensure that the fan comes on once the motor is warm.  Be aware some water temp sensors and dash gauges may actually be wrong (as much as +/-30 degrees!).  A good infrared thermostat is a wise investment to get accurate temps
  12. IF YOUR FAN NEVER COMES ON AND THE CAR BEGINS TO OVERHEAT, SHUT DOWN IMMEDIATELY. This means you have a failure of either the fan, fan switch, thermostat, or an air bubble in the system. If you have just replaced the thermostat and the fan switch you can almost certainly rule those out

I hope this walk-through and the pointers above will help everyone have a safe and easy thermostat swap in the future. If you have not picked up new parts yet, you may want to do this before you start. At the Vick Auto shop, we carry everything you need.

Remember, the faster you get a job finished, the better your chances of failure may be.


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