coolant change via coolant reservoir

[Pete85476]

It is time to drain and fill whole coolant system on 2012 Mazda 3 since it has been 5 years with 50,000 miles. My questionable approach would be to extract the coolant first thing in the morning with a small electric water pump. Refill with new Mazda FL22 coolant. Drive to work (15 miles each way). Then do this again each morning until using up two gallons of FL22.

Will this project work?


This method would eliminate the burping and be much easier without the mess and jacking the car up and taking the plastic shield. I do not have a garage, and always looking for way to do things from the top rather than under.
thanks for feedback

 

[ZeeOSix]

That method won't work, because the reservoir tank is basally just an expansion tank. If you emptied it and filled it with new coolant, there will hardly be any mixing because when the engine gets hot only a small amount of old coolant will enter the reservoir tank and mix with the new coolant. You would basically waste all your new coolant and hardly introduce any new coolant to the system.

Only way to do a correct 'drain and fill' would be to drain the system from the radiator drain, and doing it that way will probably only get you around a 50% drain.

 

[OneEyeJack]

You'd probably leave too much contaminated fluid in the system. Cooling systems are too important to not do the best job you can draining out all the old fluid and replacing it with new stuff.

Consider replacing the thermostat, checking all the hoses and the fan belt(s).

If the cooling system fails it can get expensive and you can become a pedestrian.

 

[Olas]

Can you reach the water pump and or thermostat housing from above?
You want to drain all the coolant from before and after the thermostat, not just one side of it because that's only half the coolant.

 

[FordBroncoVWJeta]

It might be easier than you think. On the top of my head at least 2 of my cars you can take the plug out within 20 seconds. look at the bottom of the radiator for the plug.

 

[RooflessVW]

All that work... I bet a local shop (dealer) could have you done on a lunch break.

I've always hated doing coolant flushes. It always results in so much waste and takes forever.

 

[mjoekingz28]

I like your idea, although I will probably never use it! Hehe.

For the naysayers that say it wont circulate, if you pour clean water into the tank and if it is colored by next week then I say it is mixing just fine.

You could also compare a sample of the used coolant to some from the new jug and look at color, sediment, test protection levels with a gauge, etc. I think nowadays, coolant stays pretty for a long time and it may be difficult to judge condition based on appearance.

 

[charbaby]

Drain the radiator at the petcock. You will have to remove the bottom shield under the Mazda3. Refill the radiator via the expansion tank. This system is self purging and you shouldn't get any air in the system. I have done this on the '06 Mazda3 in my signature which is essentially the same as your 2012

 

[barkingspider]

I would pull the lower end hose or drain from petcock if there is one. I don't think drain n fill from the reservoir is sufficient enough, but it's understandable since u don't have a garage.

 

[Chris142]

Dont mess with the petcock! If it breaks you will be up a creek. Pull the lower hose.

 

[UNC017]

Originally Posted By: 2012mazda3
It is time to drain and fill whole coolant system on 2012 Mazda 3 since it has been 5 years with 50,000 miles. My questionable approach would be to extract the coolant first thing in the morning with a small electric water pump. Refill with new Mazda FL22 coolant. Drive to work (15 miles each way). Then do this again each morning until using up two gallons of FL22.

Will this project work?


Well, there are two types of reservoir. If yours is a "flow through" reservoir where the system pressure cap is actually ON the reservoir and there are two pressure hoses leading from the engine cooling system to the reservoir, then you'll wind up doing about a 1/2 coolant change, maybe less. Not great, but at least an infusion of fresh coolant.

If your reservoir is a non-pressurized type (just a plastic cap on the reservoir), then you'll waste a bunch of coolant and actually change maybe a cup or two in the actual system, since thats about all that enters one of those reservoirs as the engine heats up. Definitely a non-starter.

 

[CR94]

Originally Posted By: Chris142
Dont mess with the petcock! If it breaks you will be up a creek. Pull the lower hose.
I disagree. If the car has the usual type of Japanese threaded plastic plug to drain the radiator, it's reasonably easy and reliable to open and close. Taking the hose off is likely to be messy.

 

[charbaby]

Originally Posted By: barkingspider
I would pull the lower end hose or drain from petcock if there is one. I don't think drain n fill from the reservoir is sufficient enough, but it's understandable since u don't have a garage.


The only way to refill the coolant is through the reservoir on this car. There is no cap on the radiator. Living in FL also shouldn't pose any issues with the petcock although pulling the lower rad hose is a very good idea.

 

[Dan55]

Owners manual says 10yrs or 190,000 KM (118,000 mi), personally I would wait. If you still feel like doing it early, your method would be fine, if you replaced it at every oil change.

 

[KrisZ]

Is the 3 in question a Skyactive model or regular 2.0 or 2.5 one?

If the car is not the Skyactive model, then the reservoir on it should be the pressurized one. It sees full flow once the thermostat opens, however it is quite small, so doing the coolant change this way will take a lot of time and will waste more coolant due to mixing. I would definitely not do it this way.

The radiator drain and fill on my 06 does exactly 50% of coolant capacity and the drain plug is extremely easy to twist off with a stubby flat head screw driver, just use a wide one. And I had no problems burping the air out. Just fill the reservoir to the max line and go for a drive. Top off, if needed, the next day and you should be done.
The underbelly shield has to come off for this, but it's not a lot of work.

Skyactive models may have the cap on the radiator and the reservoir may be only an overflow tank, I'm not 100% sure though, in which case draining it and refilling is pointless.