2007 mkx with 90,000km.

I was wondering, if I put a cleaner and distilled water to clean the system because the coolant is low and I see some floating residu and white stuff in the tank.

Should I proceed the same as getting air out. Rev up to 3.5k rpm and etc. Or just pour everything in and let it idle for a long while? Thx

 

A lot depends to a certain extent on the instructions that came with the cleaner.
It is usually recommended to drain and flush the cooling system after using the cleaner.. To do that properly you should remove the thermostat so the flush can get throughout the engine. Then of course you are supposed to refill the system with the proper concentration of coolant to maintain corrosion control, boiling point and all that. It is not a good idea to run any engine with a low coolant level so hopefully you can find a spot to open and let trapped air out while filling. You might even need to bleed the air out of the heater hoses too.

Usually the white stuff is what we call solder bloom and it looks like calcium deposits. The best way to get rid of that is to send the radiator out and have it professionally cleaned chemically. Then that opens another chapter where considering the year of the vehicle ,the radiator may require replacement once the deposits are removed.

I wish I could offer some better suggestions other than, If there are no problems with overheating,drain out as much of the old coolant as you can and install the correct amount slowly and maintain the better corrosion protection with the replenished coolant.

 

As Hanky said if you use a cleaner make sure to flush the system out aftewards completely otherwise the cleaner could cause problems with how it reacts to the coolant. Personally I dont like using coolant cleaners, I just drain and fill.