If you have not checked or refilled the coolant reservoir in several months, you will observe a slow loss of coolant ... the level observed in the bottle next to the fender ... that is just due to evaporation. The heat produced by the engine, and also ambient temperatures will also contribute to the evaporation rate.

As a first guess, wait until the engine is cold and remove the radiator cap ... the one that is on top of the radiator. Then get some coolant ... either 50/50 antifreeze/distilled water ... or just plain distilled water and top off the coolant level inside the radiator. Also remove the cap from the reservoir bottle and fill that to the level indicated on the side of the bottle.

Then you will have to inspect the coolant level in the reservoir bottle daily for several days. If you see that the reservoir bottle is going dry, then you might have a coolant leak or loss someplace. If you do suspect that there is a leak, or coolant loss somewhere, then you can have someone put a pressure tester on the top of the radiator and pressurize the coolant system.

The pressure test is a very good method of testing the system. However, if someone is demanding a fee to test your coolant system, I would suggest the idea of just filling the coolant system to normal levels, and keeping an eye on it for a day or two.

Typical coolant loss problems are: worn out radiator hoses, radiator leaks, heater core leaks, and also damaged head gaskets which leak coolant into the combustion cylinders. Also, the radiator cap should be replaced after a few years. The radiator cap allows coolant to flow to and from the reservoir bottle into the radiator, depending on the temperature of the coolant. ... Suggest getting an OEM radiator cap ... a dealer sold part, to insure proper performance.

 

Thanks for your detailed response, attached image can you please confirm. Green circled is the one and Red Circled is the radiator cap, where coolant needs to filled, I can use Prestone 50/50.

Thanks for your time.

 

You can use Prestone 50:50 provided your existing coolant is green or yellow. If it is red, do not use Prestone 50:50 - in this case, you need to use a coolant compatible with Asian cars.

How often do you check the coolant level in that overflow reservoir? It should be checked periodically (monthly recommended), just like your engine oil level.

 

I used to check periodically earlier but now after recent oil change when I checked it is completely empty so I have filled it will Preston 50:50 which is green in color, which I had used for same car almost year ago.

But after seeing your comments that I should fill it with Green or Yellow provided if the coolant which exhausted was either Green or Yellow.

But today when I was filling coolant reservoir which was almost empty I think the liquid which exhausted might be red. Will that be a problem because I filled up with Green one.?

 

All I can tell you with certaintly is these two coolants should not be mixed in the same cooling system. All one or all the other, but not a mix of the two. Toyota Red is a HOAT coolant, Prestone is not. I would recommend you determine quickly why your coolant level had dropped so much and fix that. After the fix, flush all the old coolant out and put one kind or the other back in - and stay with that kind if you ever need to add in the future.

 

The red circle is the reservoir cap. The green circle is the "radiator cap", even though it's not on the radiator.

 

Thanks all for your response.

 

I went to Auto repair center and had conducted 'Cooling System Pressure test' to determine the issue and it seems to water pump and they gave below estimate

If water pump is leaking there would be coolant dripping on the ground, which I don't see now.?

As far as estimate is concerned, is it fair?

Appreciate your reply.

 

If water pump is leaking there would be coolant dripping on the ground, which I don't see now.

No.

We had an issue with our 97 camry. The reservoir would slowly go down and we could never find any trace of a leak We had it pressured tested and they could not find anything.

It turned out to be a small O ring that sits between the water pump and the engine. Having done the job myself this O ring is the weak link in the chain of the coolant system. The condition of the water pump after 17 years was excellent. Aisin did a superb job.

Buy the OEM parts yourself from Amazon and find a good shop or mechanic to do it. That will save you a bundle.

 

Kinda steep price, but it is good they are doing the timing belt with the water pump. I'd take it to a couple of other shops (I looked on Google maps for highly rated garages and found one that is great, hopefully you can do the same).

I would expect about $700. It is an involved job. Have them do a cooling system flush and refill with toyota red.

I would not expect for you to be able to watch it drip out unless the leak was really bad, but you may be able to see a small puddle overnight.

Composed on a phone using AutoGuide App.
Please excuse typos / brevity.

 

On my 5S-FE, the water pump has a small inspection hole on the external case ... I think it is called a weep hole. At any rate, if you get a flashlight and can see coolant inside the weep hole, that is an indication that the water pump bearings are going out, and is a sign that you should replace the pump. It is probably the same on your V6. Coolant doesn't have to drip out onto the ground ... just that it shows up in the inspection hole.

 

Estimates will vary depending on the demographic area you are in. Seeing coolant is not always obvious. The Water Pump has a weep hole where coolant can leak. Inside the pump is an inpeller which when rotating moves the coolant. The Impeller is attached to a bearing. If the bearing has not shifted or gone bad enough,the leak might not be visual except under pressure.

I have attache a picture of a water pump so you can see the weep hole. This pump is not the same as on your car though. Theory will not change.