Coolant drain and refill

[sftibbs]

I drained the coolant (SB 350) by opening the peacock and removing engine block bolts. Drained about three gallons. When refilling, less than one gallon brought the radiator to full. What am I missing 

[tmodel66]

Have you started it since you filled the radiator? If not the block will need to fill up when you start it. Water level will go down.

[sftibbs]

I have not. I was thinking water needed to get into the block but wasn't convinced I could start the motor with no coolant in the block. As I understand you, I can start the motor and fill the radiator as the coolant goes into the block as the level will go down?

[janobyte]

yes,if you are worried top it through the intake ( thermostat ) replace thermostat ,housing etc... BTY if you are in the habit of draining for winterizing don't forget the heads if you aren't running an antifreeze mixture.

[JohnZ]

System holds about 4 gallons. From an empty system, I usually fill the block through the thermostat opening in the intake until the level comes up, then install the thermostat and housing, and finish filling through the radiator filler neck. Start it, run until the thermostat opens, and adjust final level. After it's cooled overnight, check level again - it should be a couple of inches below the filler neck, where "full cold" is embossed on the side tank.

[canadair]

just remove one end of a heater hose replace  it when then fluid comes out use only distilled  water

[sftibbs]

I filled the block through the thermostat opening and put in a new thermostat since I was there. When I start the vehicle and it gets to operating temp, the engine starts to overheat and the radiator is cold. The radiator was gone through prior to restoring the car and along with the water pump has few miles on it. The thermostat is new? Could it be trapped air in the system? If so, what's the best way to bleed it?

[Mike S]

 I have always had great success with the 'burp' method. While running and hot enough for the thermostat to be open I would grab the upper hose and squeeze hard rapidly many times until you hear a faint burp like sound which are the air pockets finally escaping.

Mike

[sftibbs]

Thanks Mike, with the cap on or off?

[Kelley W King]

Although I have not tried it, there was an article written lately by an engine builder who drills a 1/8 inch hole near the edged of his T-stats when new to help purge the air. I will be trying it soon.

[Mike S]

Thanks Mike, with the cap on or off?

For mild squeezes I leave the cap off to see if the water level suddenly lowers which would indicate the air ipocket s worked out. Otherwise I'll put the cap on and give it rapid squeezes. It can take some coaxing but I have had this work very well.

Mike

Mike

[Mike S]

Although I have not tried it, there was an article written lately by an engine builder who drills a 1/8 inch hole near the edged of his T-stats when new to help purge the air. I will be trying it soon.

I have seen thiese already drilled in t-stats from parts stores. That's a good point to bring up however.

Mike

[JohnZ]

I've been doing this for over 55 years now, and have never drilled any holes in a thermostat, nor have I ever had any "air pockets". At the first start cycle after a complete refill, leave the cap off (or loose) until after the thermostat opens and then you can adjust the level.

[69Z28]

Just as JohnZ says. I have found on occasion that when filling an engine that is completely empty that air gets trapped inside the block and assuming other places as well. I bought a 69 Judge from a friend back in the 90's and he couldn't get it to stop overheating. Did a little research and found if you leave the radiator cap off and let the engine run at operating tempature the air will enventually be burped out thru circulation as you keep adding fluid. Chevy engines don't seem to have as much of a problem as the Pontiac engines do, at least the ones I have owned anyway.

[tmodel66]

I filled the block through the thermostat opening and put in a new thermostat since I was there. When I start the vehicle and it gets to operating temp, the engine starts to overheat and the radiator is cold. The radiator was gone through prior to restoring the car and along with the water pump has few miles on it. The thermostat is new? Could it be trapped air in the system? If so, what's the best way to bleed it?

Can you see the water circulating in the radiator? I have always just started it up with cap off. When the thermostat opens the water level will drop. When you add coolant that will force any air out of the system as it continues to circulate and fill the voids with nothing but head pressure from the radiator.