I just flushed my radiator and bought two gallons of antifreeze. I have a 1998 GMC Sierra 2500 4X4 454 7.4 L. How and how much antifreeze/water do i put it. I have no owners manuel.

Question moved from Spanish Car company Seat (pronounced See-At).

That's hilarious and the very first time this has been posted on Fixya in my 12 year term with nearly 50,000 questions answered!

Well it will smell nice, but won't do much for it antifreeze capabilities. Did the cooling system take the whole gallon? That is a lot to be under-level! As it is new to you, it would be a good opportunity to drain the system and do a flush and a top up with new antifreeze and demineralized water. It is fairly easy once you find the drain on the radiator.

Google

year make model coolant flush

You also have to burp the system of air which is covered in a Tip I wrote.

https://www.fixya.com/cars/r29872074-vehicle_cooling_system_no_heat

'year make model' should be the first three words in every question please Also the Fixya scripting will usually offer you the correct category..

It depends on where you live. If it doesn't get below 10 F, one gallon of antifreeze will do. Then fill it the rest of the way with water. If you measure how much of water added, there is a table of temperatures on the bottle to let you know your protected temperature.

you might want to check the wires going to the temperature sensor on the engine make sure it hasnt rubbed the protective coating off, this can give you a false reading, the safest way is to put a manual gauge in place of the temperature sensor and run engine to make sure the engine is not overheating. You can pick up a cheap manual temp gauge at your local parts store and install the temperature probe into the hole where the temp sensor was located and run the engine. It sounds like you have a guage malfunction. But is better to be safe than sorry.

I am assuming your vehicle has the pink antifreeze called Dexcool. This is the recommended coolant for all late model GM cars and trucks. This coolant tends to form a pasty sludge in the cooling system which can lead to overheating and/or plugged up heater core. Try flushing the cooling system with a good aftermarket product such as prestone radiator flush. First thing to do is drain all the pink coolant, then add the radiator flush and fill with plain water. Run the engine according to directions on the flush container. Drain the radiator again and refill with plain water. Run the engine for a few minutes and drain again. Keep repeating this until all the pink antifreeze has been eliminated. Fill the system with 2 gallons of green antifreeze. Make sure the antifreeze container says it is compatible with aluminum engine parts. Hope this helps. If it does, then you won't have to replace the heater core.

If you are draining your radiator, or just need to add some, there are a couple of options. You can either buy antifreeze in a 50/50 premixed solution, or purchase one gallon of antifreeze and 1 gallon of distilled water (less than $1.00 at your local grocery store) and mix equaly in another container that way you have a proper mixture in your radiator. The 50/50 mixture comes in an orange color and the full strength comes in the traditional green color.

It will need as much as it takes, which is impossible to tell depending on how you flushed it.
But your whole system takes more than 2 gallons, and since you want a 50/50 mix you know you will need more than one gallon of antifreeze. So you need to start by purchasing 2 gallons. If you have left over, it does not go bad. And if you do not quite have enough, you can probably add a little extra water because you probably did not flush all the antifreeze out.
Once you run it, then next time it will need more again after the heat bleeds the air out.

You can put it in the recovery tank (white plastic most of the time, sometimes black), maybe 1/2 gallon at a time 50/50 antifreeze to water mixture.

Run the car, and watch the temperature gauge.

Sometimes, if the radiator is cool, you can undo the cap by pushing down and twisting counterclockwise and add directly to the radiator.

buy you a new temp sensor from the dealer not autozone,try that,my suburban did the same thing cause i got a cheap piece of **** sensor from az

Your thermostat may need to be replaced and your water pump may be weak and need to be replaced also. Try replacing the thermostat and flushing out the coolant system and replacing it with new antifreeze. Also inspect the radiator hose, check for the condition there in, if there too soft and when they get hot, the hose may collapse and restrict the flow of antifreeze though the system. After that has been done and you are still over heating, the water pump could be weak and needs to be replaced. Recap: service the cooling system with new 50/50 mix antifreeze, replace the thermostat and replace any coolant hose that is soft. Good luck and hope this helps, keep me posted, be glad to help.

You have to disconnect the bottom tube to the radiator. Be sure if you have antifreeze in it you drain into a bucket because its sweet to bugs and the bugs will be there in an hour if you dont.

Hope this helps