Cooling system capacity significantly less than manual states

[84K30]

Decided to service my cooling system today. First, I ran an off-the-shelf "cleaner" in the system for about 100 miles before draining the system via the lower radiator hose. Also, I ran about 5 gallons of water through the engine until the fluid exiting the block appeared clear. I removed the rad and flushed it with water in the same manner as I stated above. I also hosed off the fins on both sides. I replaced both the upper and lower hoses, the thermostat & gasket, water neck, temperature sensor/sending unit (195 degrees(confirmed operation before installing) and radiator cap. I also removed and flushed the overflow tank and hose that connects it to the radiator. Upon refilling my system, I only managed to use 4 gallons of the 50/50 mixture before the system was full. After getting my truck to temperature (radiator cap off), which topped out at approximately 210 before going back down, very little additional space was created. I have no leaks. My service manual lists 24.5 quarts for 454 trucks with AC. Any ideas what may be going on? Thanks!

 

[nvrenuf]

Capacities are total and assume the given system is dry. You certainly flushed it but it’s very unlikely you emptied the bottom half of the block (below the level of the water pump). Watch for temp fluctuations in case of air pockets but you should be good.

 

[84K30]

Thanks for the clarification. I tried to burp the system by squeezing the upper hose while the engine was running and the radiator cap was off. I'll just keep a jug of coolant in my truck and check the level periodically until I feel confident enough not to. Thanks again for the reply!

 

[Bextreme04]

There,s a lot of coolant that stays in the block when you drain it, unless you pull the coolant drain plugs on the block as well.

 

[F-64]

Yep, just like John said. You have coolant still in the block.

Sometimes I use this when filling a system to get most of the air out.
https://www.lislecorp.com/specialty-tools/spill-free-funnel-606

If it's a tough to burp system I vacuum fill it.
https://www.cpsproducts.com/product-details/550500/