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  1. #1

    Default coolant drain plug [Expired Topic]

    I have a 1994 7.4 liter engine. Where is the drain plug to drain the coolant? I want to flush and replace with fresh coolant but I can't find the drain plug on the engine. The specs say there are 25 Quarts in there but when I drain the radiator I only get about 10 Quarts. Any help will be greatly appreciated.

  2. #2

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    I'm not exactly sure where the plugs are on that engine, but I wouldn't mess with them even if I did. They've been in there for 11 years through lots of heat cycles and are probably rusted in. You could easily strip them or break them. I would remove the upper and lower radiator hoses from the engine and put a water hose in the holes and flush it out that way. I would start with the lower and then switch to the upper. You will probably need to pull the thermostat (this is a good time to replace the thermostat with a fresh one (cheap insurance)) to make it flush better. You will still have pure water in the block, but just compenstate for this when you fill the radiator with coolant to get close to a mix of 50/50 coolant to water.
    Gary

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  3. #3

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    I beleive the drain plug is on the drivers side tank. I've onpened several of these plugs on GM trucks and never had a problem with them resealing.

    You may not get all the coolant out for a number of reasons. The radiator maybe plugged up with slug, from the old coolant. Your heater core or cores may be plugged also. If that is the case you can try to back flush them. Like the last post said you'll have to remove the termastat if you want all the coolant out of the block.

    I resently replaced my radiator on my '95 burban because of over heating while towing. I had a standard unit and replced it with a heavy duty one.

  4. #4
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    Default Re: coolant drain plug

    Quote Originally Posted by ziggy919
    I have a 1994 7.4 liter engine. Where is the drain plug to drain the coolant? I want to flush and replace with fresh coolant but I can't find the drain plug on the engine. The specs say there are 25 Quarts in there but when I drain the radiator I only get about 10 Quarts. Any help will be greatly appreciated.
    Backflush the entire system with a Prestone or equivelent kit. That way you are sure to get the heater core / lines cleaned out too.

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