I just drained the old coolant from my 98 F150 today, and something has me stumped. Now it seems like the system won't hold the 17.3 quarts required for a V6 with A/C. I drained every bit of the old coolant, including opening the engine block plug. I thoroughly flushed the system until the water ran clear. When I went to refill it, it only held around 2 1/2 gallons before reaching the "Full" mark on the recovery tank. I drove around for a while to let it circulate through the system, then I checked it again. I checked it once more after it cooled off. It's still right on the full mark. My truck stayed cool while I drove it around. Any ideas?

Dave

 

It's impossible to get 100% of the coolant out of the system. There is always some that sits in the bottom of the radiator, engine block, heater hoses and heater core, etc. The main thing is keeping good antifreeze in there. Every 2-3 years is a good regimen to follow. Just make sure it's a 50-50 mix. 50% coolant, 50% water.

 

With the 4.2L, between the block and the radiator, you can drain about 80% of the total coolant.

I've done this a few times and never had a problem. Are you sure you're allowing the engine to warm up enough that the thermostat opens?

 

Frank is right...you'll never get it all out.

 

I think everything is okay. I drove around for an hour or so tonight, and my truck stayed cool. I guess there was just more coolant left in the system than I thought. Thanks for the replies...

Dave