The GTM Supercar Build Log

Coolant Fill How-to

Since getting the cooling system filled was pretty annoying, and the FFR manual doesn’t help AT ALL, I thought I would post a step-by-step as to how I did it. Thanks to Henry over at the forums for helping! 

Before I get started it helps to know that you will be using 4.5-5 gallons of coolant.

1. Fill surge tank – should be able to add almost a gallon of coolant to it. Leave the cap off the tank.

2. Disconnect the upper radiator hose on the water pump.

3. Disconnect the bigger of the two ‘smaller’ hoses on the passenger side of the radiator. The hose you want to disconnect runs to the surge tank.

4. Disconnect the two steam vents at the top of the heads on the engine. You only need to open the vents on the belt side of the engine.

5. Start pouring coolant into the water pump hose that was disconnected previously in step 2. When coolant starts overflowing out of the radiator connect the small hose back to it.

6. Keep pouring coolant in until coolant either comes out of the steam vents, or it comes out of the water pump port that is open (from the hose disconnected in step 2).

If you cannot get fluid to come out of either location without the surge tank overflowing, or just cannot get any more fluid in at all, you have an air lock.  Jack up the front of the car, reconnect the water pump/radiator hose and run the engine at idle (still with the cap off the surge tank and vents open) for a minute, then put the cap on and get the temperature up to 210 by revving the engine in intervals. Shut the engine off, carefully remove the cap, and disconnect the water pump hose from step 2.  You should be able to get more fluid in – if not just let the car sit over night with the front end raised, surge tank cap off, vents open, water pump hose off and elevated. Air will work its way out. 

Repeat step 6 until you get fluid to come out of the water pump outlet or the steam vents. The first time I went through this step I had 4 gallons of coolant in the system. It took a few repeats of this step to get the last gallon in.

7. If coolant comes out of the steam vents connect the water pump hose again, and reconnect the steam vent covers/surge hose. 

If coolant comes out of the water pump outlet then top off the coolant that is in the water pump/radiator hose, and carefully connect it back to the water pump without spilling too much. Coolant should now shoot out of the steam vents. 

Run the engine like you did in step 6 and let it sit with the vents, water pump hose, and surge cap off for a few hours (or overnight like I did). If the coolant drops in the surge tank this means more air was released. Top it off again via the water pump hose. 

Repeat this step until the coolant no longer drops in the vents or surge tank while sitting. To ensure I had the coolant topped off each time I injected coolant with a baster into the steam vents until it overflowed. When it finally stayed at the top, and the surge tank didn’t drop, I knew I had the air out.

8. Top off the surge tank as needed and run the car for a while and observe the coolant circulating once your thermostat opens (you can see it circulating at the bottom of the surge tank). Both hardlines should be warm to the touch. If one is hot and the other is cold then you still have an air lock – go back to step 6 or 7.

One Response to “Coolant Fill How-to”

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