1975 300 coolant
5th Wheeling
Joined: Apr 2023
Posts: 42
Likes: 17
It should take 3ish gallons total, but that may vary depending on your radiator. I usually fill the radiator, start the truck, and keep adding coolant when the level goes down. Once it seems to have gotten most of the air out, I'll put the radiator cap on but not tighten it and then go for a short drive and check it again.
Fleet Mechanic
Joined: Feb 2022
Posts: 1,371
Likes: 707
Should be around 4 gallons if you’re pulling the block drains. Exact capacity doesn’t matter though. Just fill it until the coolant level is about an inch below the filler neck with the engine warm and the thermostat open. If you aren’t using 50/50 pre-mix then make sure to use distilled water, NOT tap water to dilute the anti-freeze.
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fski50
6.7L Power Stroke Diesel
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Apr 26, 2015 08:28 PM
