Antifreeze consumption

[MasterDent]

Hey guys,
I've 07 M35, 110K.
I noticed that I need to add some antifreeze coolant every few months, my last dealer service was (changing the radiator sensor) because I noticed that the fan goes on even if the engine is not running and cold! they said the sensor stays open and never close back again, they charged me 220$. after that service I noticed that there's no antifreeze at all!! I thought they forgot to fill it back as they said the had to empty the whole system when they changed the sensor, anyways I added some, but I noticed that the car consume it slowly, and I need to keep adding..

No white smoke, no obvious leak..

what should I do?!

Thanks

[The00Dustin]

OK, when you say "no antifreeze at all" where were you looking? Without looking, I believe the antifreeze "tank" under the hood is an overflow and wouldn't have to have antifreeze in it. Even if it is supposed to have some in it, you could just be lucky in that the system has some bubbles that are being worked out on their own via the overflow tank instead of causing you other problems. That having been said, you should check the radiator for antifreeze when the engine and radiator are cool, and you should watch the temperature gauge in the dash to make sure it is working as expected and avoid overheating (it may not move if there is no coolant, but you could still overheat, and it could move too far toward hot if there is some coolant, and you could obviously overheat then as well). Beyond that, you should provide some additional information so someone more knowledgeable can help you. for instance, is there coolant in the radiator, is there a puddle under the car, do you have any additional information or symptoms? Also, depending on when the dealer service was you could probably just send it back to the dealer if the radiator isn't full.

[Larz]

Hopefully, the engine is not actually 'cosuming' the coolant as that means very serious engine problems. The radiator could have a small leak that lets coolant out when driving it under pressure. Sometimes it is a very small leak near the top and it evaporates as it leaks due to the high temps of the engine / radiator. You won't see a puddle under the car, but it is leaking. If the dealer did the coolant change, take it back to them so they can re-flush and refill. When you say no fluid at all ... that would mean the coolant is completely gone and the radiator is bone dry. Did you mean to say the plastic recovery tank outside the radiator was empty?

[MasterDent]

First of all thank you both for reading and replying!

I meant no antifreeze in the tank, I never had overheating issues, no puddle, no stains under the radiator, the car runs perfect.

Taking the car to the dealer means whole day off and potential high charges even for problem diagnosis with no service..

I'm thinking of using some products (STOP LEAK) from Walmart? any recommendations?!

Thanks again..

[Larz]

Those products are either totally great or totally crap, depending on who you ask. My dealer always offers me a loaner so I never am without a car or forced to take a day away from the office. However, if we aren't in a comfy position for a large repair bill, getting a loaner is not all that great.

Personally, I would never use additives in my coolant because I 'believe' they can cause clumps and clumps can wreck the water pump, thermostat, etc. And, if it turns out you need a new radiator, they are much less expensive away from the dealer - like half price even. After 100k miles a new radiator might be what's needed. In true Inifniti style, it's designed to be a pain to do it yourself, but you may want to consider it.

If I remember correctly, the proper way to fill the cooling system is to fill the radiator to the top, replace the cap with a new one, then run the engine until it's warm and check the coolant reservoir tank. Fill that to the 'warm' mark, then run the engine again and see if that reservoir still indicates that fluid is at the warm mark, then let the engine cool and check the reservoir tank to see if fluid is at the 'cold' mark. Please double check me on this. There may be other steps needed to remove air bubbles, etc.
Here is a vid of an Infiniti tech draining and re-filling the cooling system. It's a G model, but it should be similar to our engines. It shows the air release valves and where they should be located.
https://youtu.be/mayYHv5vOkg

[EdBwoy]

... you should check the radiator for antifreeze when the engine and radiator are cool, and you should watch the temperature gauge in the dash to make sure it is working as expected and avoid overheating...

...Please double check me on this. There may be other steps needed to remove air bubbles, etc...

Good points above MasterDent. I would open the radiator cap and see what the coolant level is in the radiator. It might be something as minor as failure to fully purge the system of air when the shop did it.
Another step to fully purge it would be to open the relief plug that is usually on the heater hose while adding coolant. This looks like the radiator drain plug.

For troubleshooting, might you know how much coolant you add each time/ total quantity over these months? Does your heat inside the cabin work with no issues? Do you see green/blue crystals around any rubber hose-metal pipe connections? Any greenish tint along the top of the radiator where the aluminum meets the plastic? Does the coolant reservoir seem old/cracked/browning etc?
I do not normally support such additives unless it is a very serious issue and there's significant risk of overheating.

[MasterDent]

Hey guys, I took this vid tonight, do you consider this white smoke?!

https://www.dropbox.com/s/khpqqzzt00bf4 ... 9.mov?dl=0

The car heater works fine, I rev the engine for about a minute, no overheat just the fans went on, the antifreez tanks looks pretty good, no stains.

I added about half of the preston gallon antifreeze 50/50 so far.

[EdBwoy]

Honestly, I can't accurately tell the color of smoke at night through a rear view camera displayed on a DVD screen, that was recorded on yet another video device and finally displayed on my phone and perceived by my poor eyesight ... but on a serious note, that seems like a lot of smoke action you've got going on, even considering the revving, but it is typical at startup on a cold day. And half of that coolant jug is quite a lot to have to top off after being professionally serviced.
Are you adding this to the radiator or to the plastic reservoir?

Another test would be to go and smell the smoke. Coolant smells sweet as they say, and it has a weird aftertaste. I don't have any other substance to compare it to, unfortunately, but you'll be able to tell if it smells "different".

[EdBwoy]

Oh, another source of a leak could be your radiator cap. Under higher pressures coolant could escape through the top and get caught in that sound deadening/ insulation mat attached to the hood. This will show up as white spots on that mat (largest spot lining up with the source if the leak of course) and various locations in the engine bay and you might never see a puddle on the ground.

[MasterDent]

Hey guys,

Almost 2 years follow up, I still need to add some coolant every few months,
but finally I found out where the leak is! I was changing engine oil and I found coolant dripping from the AC compressor!!! what does it mean?

here's link to the picture https://www.dropbox.com/s/3zbhenyqhro6p ... 6.JPG?dl=0

[Ilya]

I'm going to delete your other thread as there is no reason for the duplication.

Not sure what coolant leaking from the compressor will suggest other than it might be time to change it.

[EdBwoy]

... Do you see green/blue crystals around any rubber hose-metal pipe connections? ...

Well, isn't there a place where the lower radiator hose meets the metal tube sort of above the compressor?
Otherwise, look at any coolant tubes above the compressor and find which one is leaking onto the unit.

Touch that stuff too. Coolant is watery, compressor oil is greenish too, but it is well, oily, and would leak from the same mating surface.

[MasterDent]

Thank you EdBwoy, I'll update you as soon as I check it!