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I am a little embarrassed to ask this question but I have to ask it anyway. Yesterday I drained the cooling system by the petcock in the bottom of the radiator and flushed the system with fresh water. Today I picked up the antifreeze and mixed about 24 quarters. I was very surprised when overfilled after about 12-13 quarters? Do I really have to start the engine to fill up the system? Is this because of the water-pumps or the thermostats? Just want to be sure before I do anything stupid!
Thanks!! Mats Nilsson, Sweden
If this is a flathead with a stock radiator, they take most of 5 gallons of antifreeze. You should be able to put in +/- 20 quarts.
The T-stats do restrict the system somewhat. You can start it to get things circulating.
Along with what has been said above, the book says 23 US quarts which would be ~19 imperial quarts (OP is in Sweden and so units can differ). Also, draining from the petcock may not completely drain the system dry.
No I did not drain the engine block. I thought almost all water could be drained from the petcock on the radiator because the petcock is lower than the lower radiator hoses. I now regret I did not measure the water I drained!!! I filled with about 12-13 US quarters but expected about 23. How can I drain the coolant from the engine block? Thanks a lot !!!!!!!!!
Abe. I dont find any petcock on the block, neither left or right side of the block. I dont know if all engines, all years have these. My engine is a 8RT but I am not sure about the year. Thanks!!!!
I have never been able to get more than 18 -19 quarts into the system, even with a dry engine after a rebuild. It depends on the radiator (stock or not). It does help to get it running with the cap off, and keep adding as the thermostats open. Make sure the heater is in the circuit too. Keep in mind the radiator shouldn't be filled to the top even when hot.
I found what I think is the best way to fill the cooling system on a flathead v8.
Remove the temperature sensors from the heads, fill until the coolant overflows out of the sensor holes then put the temperature sensors back in. Continue filling until the coolant is about 2” from the top of the radiator.
I’ve done this several times and never had air in the system.
Abe. I dont find any petcock on the block, neither left or right side of the block. I dont know if all engines, all years have these. My engine is a 8RT but I am not sure about the year. Thanks!!!!
un
Whoops, sorry. When I saw 239 I thought in my Yblock brain you had a 239 Yblock.
Thanks a lot everyone! I am going to start it today and see if I can fill up some more coolant. One more question. I have a heater shut off valve on the passenger side head but I dont know for sure if I just turn it 90 degree to open ( like the petcock) or if I have to turn it counter clockwise several rounds?
When it have threads I suppose I have to turn it multiple rounds to open??? Thanks! Mats
