Correct way to fill completely empty cooling system?

[MoparGuy68]

I completely back flushed my 383 block, and heater core. And forward flushed the 26" radiator (was too inconvenient at the time to black flush it). Afterwards I blew block, heater core and radiator out with compressed air. So the system was dry, totally empty. I installed all hoses, and a new 180 degree thermostat, I did NOT leave the thermostat out.

I then filled the radiator, with 50/50 mix conventional green coolant, so that the level was 1.25" below the bottom of the radiator neck. Next morning after seeing the level had dropped some, I added more to get it at the 1.25" level. At this point I had added only a total of a little over 2 gallons of 50/50 coolant. The manual states the system should take 3.6 gallons.

Reading the following in the service manual..

Service manual says:
(5) Fill Cooling system to 1-1/4" below filler neck, using soft water and anti-freeze, depending on season or if equipped with A/C.
(6) Engine should be operated until temperature gauge indicates normal operating temperature, then continue an additional five minutes to release any air trapped in system.
(7) Check for leaks and coolant level; correct as necessary.

Started the engine for the first time in 5 months, with the radiator cap removed from the radiator.

Engine fired up, kicking up to fast idle speed. I let it run a little bit, then tapped the throttle to drop down to curb idle. Looked in radiator, coolant level had gone down only a little bit. I added a bit more coolant to get it about 1.25 below the filler neck bottom.

Then this is where things went horribly wrong.. As temperature gauge started to reach normal operating temperature (second tick mark from left on temp gauge in rallye dash), coolant started bubbling out of the radiator neck. I panicked, and turn the engine off.. When I did this, coolant started erupting out of the radiator neck like a volcano!! It went ALL over the place!! Drenching the radiator and the entire front of the engine. Got the Borgeson gearbox wet, the power steering pump and pulley. Spilled out onto the garage floor. It made a huge mess! I spent an hour sopping up coolant with paper towels, sponges and a mop.

Instruction in step 6 and 7 above are completely inadequate.. I now have no idea how to fill the system. If I was supposed to have the radiator cap in place, how am I supposed to check the coolant level and correct as necessary? There was still close to 1.5 gallons of coolant that needed to be added at the time of the eruption. At the time it erupted there was only a little over 2 gallons in the whole system.

Could someone please explain how step 6 and 7 should actually be performed in detail, so I don't repeat this disaster again?

 

[dadsbee]

I fill the complete system with distilled water as full as I can waiting for it to level itself out and the rad almost full. Run it briefly, WITH THE CAP IN PLACE, and shut it off and let it cool. Then check to see the level, top if necessary and run again to temperature and check for any leaks. No point in blasting glycol over a fresh restoration, as happened in your case. Then when everything is good I drain the radiator from the petcock and fill with 100% antifreeze. Gives about a 50/50 mix that seems to be working in at least two cars..

 

[MoparGuy68]

I fill the complete system with distilled water as full as I can waiting for it to level itself out and the rad almost full. Run it briefly, WITH THE CAP IN PLACE, and shut it off and let it cool. Then check to see the level, top if necessary and run again to temperature and check for any leaks. No point in blasting glycol over a fresh restoration, as happened in your case. Then when everything is good I drain the radiator from the petcock and fill with 100% antifreeze. Gives about a 50/50 mix that seems to be working in at least two cars..

You do this procedure with or without a thermostat installed?

I made a mistake of not having the cap in place before the engine reached normal operating temperature. I guess the thermostat will NOT open and allow flow through the whole system, unless the cap is in place. So it must be done in stages with the cap in place. Run engine until it reaches operating temperature, and shortly after shut it down. Then let the system cool down, remove the cap, check level, add coolant if needed and repeat until the level no longer goes down after a run session.

 

[Ranger16]

Then this is where things went horribly wrong.. As temperature gauge started to reach normal operating temperature (second tick mark from left on temp gauge in rallye dash), coolant started bubbling out of the radiator neck. I panicked, and turn the engine off.. When I did this, coolant started erupting out of the radiator neck like a volcano!!

Cooling system basics.
The radiator cap allows pressure to increase, thus raising the boiling point to as much as 260° - 280° depending on the cap pressure rating. With the cap off, a 50/50 mix will boils at about 226° and you can only run it for a short time before you reach that point uncapped. When you shut it down, you shut down the cooling system, but the engine can't dissipate heat and continues to boil and puke coolant. Follow Dadsbee's advice, check and top off after it cools down.

 

[Ranger16]

You do this procedure with or without a thermostat installed?

With

 

[dadsbee]

Thermo in place! AND there is no reason you can't run it, let it heat up and wait in anticipation of seeing the thermostat open and the flow start in the radiator neck.... then put the damn cap in place.

 

[MoparGuy68]

Should heater controls be on or off? I had the selector in heat position, and the temperature all the way over to the right, the hottest setting. I did this because I was trying to fill the heater core.

 

[dadsbee]

Say what.. what year car? If '68/9/70 there is no heater control valve, it's on ALL the time, unless maybe an A/C car with a valve.

 

[MoparGuy68]

1971 Charger Super Bee.

Say what.. what year car? If '68/9/70 there is no heater control valve, it's on ALL the time, unless maybe an A/C car with a valve.

Here is a photo of my controls this is a non-AC air grabber car. Photos uploaded directly from my phone are ALWAYS upside down. Have no idea why..

 

[diesel_lv]

I had my '67 completely empty, block machined etc. New radiator, hoses etc. Filled, run, cool, top off, run, cool, check. Not even close to 3 gallons total w 26" radiator. When I drain radiator through petcock only, it takes approximately 2.25 gallons to fill back up. On a 383.

 

[MoparGuy68]

I just ran it second time, with the cap ON the entire time. Will let it cool. And check the level again tomorrow. After "cleaning" the threads on the fuel lines running to the Holley 4160 dual feed carburetor, because they looked filthy, I now have a small fuel leak. Primary line and secondary line get damp. With a very slow drip on the primary line. These are flared tube ends that are NOT supposed to require sealant. I have them as tight as I can get them.. The problems just never end with this car.

This sucks running the car in the garage with front facing the street. I am getting some exhaust fumes finding their way into the house. I can't turn it around and pull it in nose first, until I fill and prime the power steering system. It feels like a gas chamber inside the garage (with the garage door fully open). Burns my eyes too. I'm not sure if these old cars are worth the trouble.. So ******* hot in Phoenix right now, I cannot open the house to air it out.. Doing this work in 110+ degree heat is absolutely miserable!

 

[bm02tj]

100% antifreeze will damage seal
The cooling system needs pressure to get all the air out so use a tester or heat up with cap on then cool enough so no pressure then add more run again
Not to hard

 

[1 Wild R/T]

Remove one heater hose at the heater core, that will allow the air to escape... Fill the radiator till fluid starts to pour from the heater core... As you lower the heater hose to attach it fluid will also come from the heater hose... Put the hose back on leaving a small gap at the top, add more coolant till it comes out of the small gap then put the hose on fully... There shouldn't be any air left in the system....

A good trick to tell if there's still air in the system? Rev the engine while watching the coolant level, if it drops theres air in the system, air compresses allowing the level to drop... If you rev it and the coolant stays steady you have no air in the system...

 

[69L48Z27]

I had this happen once too, no fun. I started drilling an 1/8” hole in the rim of my thermostats. Now all I do is fill it, put the cap on and run it. Once cooled give it a look and see if you need to add any. 1/8” hole seems to let the air bleed out behind the t-stat.

 

[artr8]

Clarification from post #13.
1 Wild R/T
What you experienced is an air pocket in your heads, hottest point in a running motor. When the thermostat opened, the steam in the air pocket took the path of least resistance and blew out the radiator fill.
To avoid, pull off the top heater hose at the bulkhead. (As recommended) Fill the system, with car not running, until you get a trickle of coolant from the bulkhead or hose. This allows your coolant mixture to fill your block and heads before start up.

 

[steve340]

The water is expanding as it heats up - so the level rises.
Leave the top tank quite low even a down by the core holes is OK - until the thermostat opens and hot water comes and the tank heats up. So long as it has a fair bit of water in it the engine is OK there is little load.
When you install a new thermostat you have to be vigilant until you are sure it is open and not faulty. Even if it is faulty you will not overheat the engine unless you run it to long.
Then top off and put on the cap before it gets to hot.
Run for a while longer and switch off - check level again when it has gone cold/barely warm.
Never remove the cap when there is pressure in the cooling system.

 

[lemondana]

Wherever I have everything apart. I assemble everything, install all hoses but the top one. Leaving the thermostat housing and thermostat off. I fill with 50/50 mix thru the thermostat base to about 1/2 inch below the flange. Install thermostat and housing with sealer of choice. Let it sit over night, install upper radiator hose and clamps, fill radiator, install cap, and start up. It will have enough coolant to break in the cam or whatever. I always figured the temp guage doesn't measure air, just liquid.

 

[MiradaMegaCab]

Safety tip, never open the radiator cap without first squeezing the upper radiator hose to see if the cooling system is pressurized. If the hose is soft and collapses as you squeeze it, there’s no pressure buildup. If you squeeze your hose and it’s rock hard, don’t open the radiator cap as you’ll take a bath in hot coolant.

Conclusion; remember to squeeze your hose. Lol

 

[hunt2elk]

I always dump in as much coolant as the block will take through the hole where the thermostat sets. Drill a 1/8" hole in the rim of the stat. Install the thermostat. Install the top hose, and fill the radiator. Run it with the cap on till the stat opens. Let it cool, and then top off the radiator. Doesn't take much to fill the system at this point.

 

[slepr1]

I can't turn it around and pull it in nose first, until I fill and prime the power steering system.

Forget the rad for now and get the power steering system filled up. Turn the car around and you can breath again.