I have a 05 4.2L and tried to change the coolant. Started the truck, turned the heater on low, turned off truck, took the top off of the reservoir, opened the drain on the radiator, and only got one gallon. What did I do wrong?

 

anybody???

 

Maybe the bottom of your radiator is clogged up, gently stick something in the hole and be ready for a flood. On the bottom center of both sides of the engine block are plugs that can be removed to drain the block, same thing when removing them, if they're not plugged expect a flood.

 

Sounds like you did not run the truck long enough to heat the coolant up enough to open the thermostat. I would leave the drain plug out or remove the lower radiator hose from the radiator or block (which ever is easiest) and then start the engine and turn the heater on and wait for coolant to start draining out. When the coolant begins to drain from the block, let the engine run for another minute or two and then turn the engine off. Once it's finished draining, put everything back together and then fill the new coolant from the pressurized reservoir. Make sure to start the engine half way into filling the system so the coolant can cycle through the block.

 

Thanks for this info, I'm also planning on doing a coolant change this weekend.