I think you need to go back and watch those videos again. How would you drain the entire system from the reservoir when that is the highest point?

All they're doing is getting the coolant out of the reservoir to get it all.

 

You need to drain it from the drain plugs or take off the bottom radiator hose connection to get most of it out. I normally forget about draining the block.
Don't forget to let the engine run until it gets warm with the heater on full heat then recheck the coolant level - to clear any airlocks.

 

Before adding new coolant , flush the system out with a hose in the header tank, the engine running and the drain partly open until it runs clear, then use soft water if possible unless your water is soft. At one time you could remove the thermostat whilst flushing , but they are inaccessible now.

 

The thermostat is actually quite accessable. Only catch is the gasket is around the edge of the thermostat like many cars so completely removing it to circulate your flush doesn't work. A good way to pull this off is to buy a new thermostat and cut the cuts out of the old one with some tinsnips. You're left with a ring basically and you can put the gasket on that.

 

Now you mention it ,yes you have to buy the cover with the thermostat in it like a sealed unit, plus its on the side of the engine as well , where as years ago before the Japanese cars appeared they were on the top of the cylinder head and the pump was underneath on the block. Nothing was inaccessible but as soon as they went for transverse engines you had to be a contortionist or own some peculiar shaped tools.

 

I'm finding your posts extremely misleading. Not sure where your information is coming from or where you're going with it.

Let us be clear. The skyactiv-g motor that this tread pertains to has only the thermostat and gasket as a single part. It is not integrated with the housing nor do you have to buy the housing with it - it is a separate part. It is also very easy to get to with a 1/4" socket wrench. Minimal parts need to be removed. How would I know this? Because I just did this job this past spring.

Having worked on many Japanese cars I have yet to run into the thermostat being integrated with the housing as a single part. With that in mind, I freely admit that there are plenty that I have not worked on and nothing newer than my 2015 so far. I have found the integrated housing in many North American cars though. Not sure what the European cars are doing these days.

But in reality this is all irrelevant. This thread is about doing a coolant flush on a skyactiv-g. This is why I'm finding your posts misleading. You're suggesting that our cars have integrated thermostat and housing. New members wouldn't know any better.

 

Heres one thermostat for a Mazda 3 and its sounds like he is from your side of the Atlantic, the older Mazda 6's were the same set up. When I looked up thermostats for Mazda 3 on Google there were various designs similar to video and also one with just an element as they used to be, that video showed the thermostat on the engine side below the water pump.

Nothing confusing about that.

Its possible they build one style for North America and another which meets Euro 6 emissions for the rest of the world. Are Mazdas for North America made in South America, not Japan as my m6 is.

Mazda design a good series of cars, but recently they have been plagued by QA problems in the manufacruring of subbed out items such as rear brake calipers (the rubber gaitor on the slide pin too short allowing water in and causing them to sieze on this pin). The fix/ bodge was to pack the gaitor out with washers, my Service Manager was having none of that, he fitted new calipers and claimed the pin was rusty, Mazda were paying , not the customer.

AC evaporator covered in flux after manufacture causing white powder on the dash. They should have been pickled to remove it. New evaporators fitted. No doubt when they were sent back they would have been pickled, flushed and capped and put back into stock. Though its not often we need the AC on with summer temps no more than 25°C , but for two years we were experiencing 35°C, most unusual.

 

Heres one thermostat for a Mazda 3 and its sounds like he is from your side of the Atlantic, the older Mazda 6's were the same set up. When I looked up thermostats for Mazda 3 on Google there were various designs similar to video and also one with just an element as they used to be, that video showed the thermostat on the engine side below the water pump.

Nothing confusing about that.

This is schematic for skyactive-g:

Spoiler

And, clearly, you can not fit all these different thermostats (on your pic) in one engine, so it must be obvious that google picture search is not so suitable for auto parts. (to put it mildly).

 

Never heard of a Gen 4, but there was a Gen 3 Facelift with more toys that you don't need.
A motorised valve controlled by the ECU sounds like a recipe for disaster, too many parts to go wrong, especially in the confines under a modern cars bonnet. The wax bulb thermostat has stood the test of time costs a few notes from your wallet, but a motorised valve and a sensor is a mortgage job as most sensors less tax are £100+ then there is the fitting there off, which will be similar to the part. Keep it Simple. Once a wax thermostat starts to open you are up to temperature and it stays open. If ambient is very low like your neck of the woods in the winter a motorised valve wouldn't work any better.
When a wax thermostat fails it can either fail shut or wide open, which is safer, then you don't cook it.

 

Man where you been living, under a rock?

Generation 4 Mazda 3s debuted in 2019. Most everything was updated, including replacing the rear multilink with a twist beam....
As far as the thermostat, the old style is self regulating depending on temperature. Sometimes it closed, sometimes open, sometimes in between. The new electronic temp regulator is pretty much the same but is controlled by the ECU for various reason, including fuel efficiency and emissions.

 

Mazda 3 in England is classed as a young person or a woman's car, along with the M2 which is a badged up Ford Fiesta almost, the last one to go through the Skyactive treatment. The M3 was the Ford Focus when it changed from the Escort. But the M6 is the mans car, its got a bit of class to it, doesn't look out of place with the Volvos, Jaguar saloons, etc. Very comfortable touring car, 45-55 mpg.

You might be interested they are talking of a straight 6 M6, RWD in a year or two, 2.2/.3 in a 4 cylinder you have the problem of torsional vibration, so they fit a damper in the sump to counteract this, but it all takes driving and using fuel. They could develop the straight 6 further, even make it 1.6 but developing good torque and HP, unlike a lot of the lazy 6/8 cylinder US made cars. I drove a 3.8 Buick, an Oldsmobile and a Chevy truck when I lived in Florida (until I bought a Datsun 200SX), none of which were very fast, especially coupled to a 3 speed auto box.

 

Mazda 3 in England is classed as a young person or a woman's car, along with the M2 which is a badged up Ford Fiesta almost, the last one to go through the Skyactive treatment.

Mazda hasn't made any Mazda 2 cars based on a Ford Chassis since 2014.

You might be interested they are talking of a straight 6 M6, RWD in a year or two, 2.2/.3 in a 4 cylinder you have the problem of torsional vibration, so they fit a damper in the sump to counteract this, but it all takes driving and using fuel. They could develop the straight 6 further, even make it 1.6 but developing good torque and HP, unlike a lot of the lazy 6/8 cylinder US made cars. I drove a 3.8 Buick, an Oldsmobile and a Chevy truck when I lived in Florida (until I bought a Datsun 200SX), none of which were very fast, especially coupled to a 3 speed auto box.

Yes, this has been discussed ad nauseum here for a long time. The Mazda 6 has been discontinued as of the 2021 model year in favor of an all new large RWD/AWD sedan that should be released soon.
As for the rest, I have no clue what any of that is all about......

 

I don't see the point in 4 wheel drive unless you are taking the car off-roading, which considering the low ground clearance and being a saloon there is no need. I have been driving for 50 years and never got stuck in snow, even in a Austin Mini in 6 " snow. It depends if you know how to drive or not.

Automatics are no good for snow and ice as you cannot pull away in 3rd. If you have black ice on the road 4 wheel drive is not going to help you as all wheels will be spinning.
If we all have to go electric ( I rue the day) then its going to be a sad world. If only some countries did away with any car over 3 litre and maintained emission limits (I am not a Green), then the world would be a better place, doubt it would stop global warming, thats just an excuse they have latched onto for more profit making. It was California that started the emissions reduction, but then if they didn't drive around in gas guzzling tanks, used the bus more and walked, they would also be a lot healthier and they wouldn't have so much pollution.

 

I don't see the point in 4 wheel drive unless you are taking the car off-roading, which considering the low ground clearance and being a saloon there is no need. I have been driving for 50 years and never got stuck in snow, even in a Austin Mini in 6 " snow. It depends if you know how to drive or not.

You've previously stated that you lived in Florida before the UK. Something tells me that you don't really know what it's like to drive in heavy snow and ice.

 

I couldn't see the point in 4WD conventional sedans until I worked in Minneapolis one winter- then I really appreciated the AWD, especially after a snow melt and refreeze.

 

Looking forward to moving into summer here , hopefully without many bushfires this year .
Who needs the old broad arrow convict shackles when you have CV 19 lockdowns?

 

Too right cobber.

 

The discussion was about draining coolant. Why are we debating brakes, models and so-on? Is there a secret block drain plug anywhere on the Mazda 3 (2015 ,and later) that would enable complete draining of coolant or not?

 

The better question is why resurrect a thread that died in 2021 only to complain about the content of that thread