Can I add water or fluid to the reservoir till I can get a flush and fill?

Heater blows cold air, radiator is full, reservoir is empty when car is cold. Temp gauge is normal, low-medium-high settings on blower work. It just doesn't heat.

My car has 80000 miles.
My car has an automatic transmission.

Experienced mechanics share their insights in answering this question :
Yes, you can, and should, add coolant to the reservoir to make sure the engine cooling system does not run low. Add only a 50-50 (water-antifreeze ratio) coolant mix to the overflow tank, particularly if it is winter season. If you add water only, with no antifreeze, the plastic reservoir will crack if the water freezes. If the cooling system is full (despite the overflow reservoir being empty, that is you have no coolant "reserve"), a flush and fill will probably not resolve your no heat problem. Lack of cabin heat is typically due to blend door malfunctions, a faulty heater control valve, collapsed hoses and/or a plugged heater core. If the heater core is plugged it could very well require a more focused cleaning and possibly replacement. Prior to servicing the cooling system, you should resolve the no heat condition by requesting a heater diagnostic. The reason for that is if you end up having to replace the heater control valve, or heater core, you will have to drain the coolant out and of course, if you schedule a flush and fill before the repair, you’ll loose the coolant that you just paid for. Once the no cabin heat problem is resolved, a YourMechanic specialist can immediately perform a flush and fill right at your location.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

Only Use Water In The Radiator In An Emergency

If it`s really low or actually empty, you need to add fluid to your vehicle. While it`s ideal to add a 50/50 mix of coolant and water (or a pre-mixed coolant), if you absolutely have to keep driving, you can add water to the radiator to get you to your destination.

If the coolant level is low, add the correct coolant to the reservoir (not the radiator itself). You can use diluted coolant by itself, or a 50/50 mixture of concentrated coolant and distilled water.
Yes, certainly you can. Use the same color antifreeze that`s in there now. Modern automotive cooling systems should not need flushed or drained, so long as they are filled with only quality modern antifreeze and distilled water.
Water by itself can`t do the job of antifreeze due to its lack of boiling and freezing point range and its inability to protect your vehicle`s engine. Plus, it doesn`t absorb heat as effectively. In the case of an absolute emergency, you can use water in your coolant rank.
Water will NOT keep the engine running cool enough. It will boil and evaperate quickly as well. If you use regular tap water instead of DISTILLED water to mix with the antifreeze, then the minerals in the tap water will collect inside your engine, radiator, and heater core…
With your coolant reservoir empty, your coolant system can`t draw in extra coolant when it needs it. This can lead to overheating. You can top up the reservoir, but you also need to identify where that coolant went.
Running just water in your car`s radiator will guarantee overheating and damage, including to your cylinder heads and engine block. And most tap water contains minerals that will leave deposits inside the radiator, causing corrosion, shortening its life and further diminishing its ability to cool.
The coolant level should be between the F(full) and L(low) marks on the side of the coolant reservoir.”
If you`re in a jam, plain, distilled water is your best bet for a temporary fix. It is better to have some liquid in your cooling system rather than none, after all. However, using water as a replacement coolant comes with a caveat. Unlike antifreeze, the freezing point of water is much higher.
3 is that water must be mixed with the antifreeze-coolant in order to keep the performance additives (silicates, phosphates and nitrates) suspended. Without water, these important additives tend to settle. If they do that, you lose anti-corrosion and other additive protection.
Undiluted products do not have sufficient capacity to absorb the heat from the engine, which leads to overheating. Undiluted coolants can also become solid in winter.
3 is that water must be mixed with the antifreeze-coolant in order to keep the performance additives (silicates, phosphates and nitrates) suspended. Without water, these important additives tend to settle. If they do that, you lose anti-corrosion and other additive protection.
Undiluted products do not have sufficient capacity to absorb the heat from the engine, which leads to overheating. Undiluted coolants can also become solid in winter.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Can I add water or fluid to the reservoir till I can get a flush and fill?
ANSWER : Yes, you can, and should, add coolant to the reservoir to make sure the engine cooling system does not run low. Add only a 50-50 (water-antifreeze ratio) coolant mix to the overflow tank, particularly if it is winter season. If you add water only, with no antifreeze, the plastic reservoir will crack if the water freezes. If the cooling system is full (despite the overflow reservoir being empty, that is you have no coolant "reserve"), a flush and fill will probably not resolve your no heat problem. Lack of cabin heat is typically due to blend door malfunctions, a faulty heater control valve, collapsed hoses and/or a plugged heater core. If the heater core is plugged it could very well require a more focused cleaning and possibly replacement. Prior to servicing the cooling system, you should resolve the no heat condition by requesting a heater diagnostic. The reason for that is if you end up having to replace the heater control valve, or heater core, you will have to drain the coolant out and of course, if you schedule a flush and fill before the repair, you’ll loose the coolant that you just paid for. Once the no cabin heat problem is resolved, a YourMechanic specialist can immediately perform a flush and fill right at your location.

Should I flush previous antifreeze fluid before adding new fluid?
ANSWER : The antifreeze in the car now is most likely the original coolant. When changing your coolant you need to make sure that you are using coolant that meets or exceeds the vehicle specifications. Your cars antifreeze is a special long life antifreeze. The scheduled flush and replace coolant on your vehicle is 5 years or 150,000 miles. Unless you have a cooling system problem you do not need a coolant flush and change for a couple years. If you do need to add any coolant make sure you are using the exact same type OATS type antifreeze made by MOPAR. . Mixing of antifreeze may degrade the antifreeze properties

Water leak from coolant reservoir hose
ANSWER : I think you are referring to the thermostat housing elbow. To answer your question is yes it can be replaced and you should also replace the thermostat and gasket along with the 50/50 mixture of coolant and water. The system should be pressure tested to make sure the leak is the only leak you have before performing the repairs. If you’d like to have this looked at, consider contacting a certified mechanic who can diagnose your leak and make the appropriate repairs to your vehicle.

My water pump just dumped all its fluid. Is it safe to drive my truck if I fill it back up with water without a new pump?
ANSWER : Anytime there is no or low coolant in a vehicle, it can be very harmful to the engine. Low coolant can cause a seized engine or a blown head gasket.

It is recommended that you have the vehicle towed to a location to have the cooling system repaired. If you can, refill the engine with coolant, and if the fluid does not run out as quickly as you put it in, then you may be able to drive a short distance to a safe location, but it is not recommended.

If you need assistance, get a mobile mechanic, such as one from YourMechanic, to inspect and determine the source of the leak, and replace the water pump, if needed.

Why would I keep getting air and fluid bleeding through the clutch system in my 2008 Infiniti G35
ANSWER : Hello. You more than likely have a bad clutch master cylinder. These will often have a seal failure on the back side of the cylinder which will either leak or suck in air. Both of these will cause this to occur. If there are not any leaks at the slave cylinder then the master cylinder needs to be replaced and bled. If you want to have this looked at, consider YourMechanic, as a certified mechanic can come to you to [determine what is causing the clutch to do this] https://www.yourmechanic.com/services/clutch-master-cylinder-replacement

Do I need to get the transfer case fluid and transmission fluid changed?
ANSWER : Hi, thanks for writing in. I looked at your maintenance schedule for your vehicle and found that for up to 150,000 miles, it only says to inspect the fluid level and not change it. The fluids are special fluids and if you did need any work done (i.e. if there is a leak present or other mechanical problem) then make sure the correct Ford certified fluid is used.

When it is time for you to have your transmission fluid serviced, consider having a certified automotive technician from YourMechanic come to your home or office to perform the service for you.

Hope this helps and best of luck!

I filled up the windshield washer fluid to the fill line and it’s not coming out now; how do I get it to flow through?
ANSWER : Hi there. There are three individual components that comprise the windshield washer system that can be broken or damaged to cause the issue you’re having on your 2001 Toyota. The first and most common is that the windshield wiper spray nozzles are clogged or broken that spray fluid onto the windshield. The second may be the hoses attached from the fluid tank to the wiper sprayer nozzles may be detached or damaged and finally, it’s possible that the wiper pump is damaged and needs to be replaced. To know for certain, you should have a professional mobile mechanic complete a windshield wiper fluid is not working inspection; so they can pinpoint the source of the problem and recommend the right repair.

power steering fluid is spilling between cap and reservoir. Is my pump bad?
ANSWER : Hello, thank you for writing in. The vehicle is likely having issues with the power steering pump. The best way to decide without a doubt is to catch it in the act. You can do this by cleaning off the area, and having someone turn the steering wheel back and forth while you watch the suspected area. When it comes to the cost, consider the labor costs that you will pay in a shop, compare them to others, and compare them to the price of doing it on your own. Replacing the pump is not a terribly complicated fix, but you will want step by step instructions to make sure you are comfortable with the entire procedure. For more help resolving the issue, contact our service department and we would be happy to schedule an appointment.