Cold Distilled Water Flush to a Hot Engine (And Cold Sexy Autumn is Here)

[RayBallen]

Searched as much as I could on the forum and on google but couldn't find a detailed discussion on this. I'm scared to do coolant flush and refill on my 97 Z3 1.9 (Part of my cooling system overhaul) due to the following reasons:

1.) Carport (non-enclosed) where I park my Z3 doesn't allow me to do a block drain or any spillage type of maintenance. Property Rules and Security guard present not too far from my carport. I have to do this as quiet and discreet as I can. So I have to drain everything through the radiator so I wouldn't spill anything. My plan is to clear out/dilute the old YELLOW COOLANT with DISTILLED WATER like many would show in YOUTUBE (i.e. ChrisFix) before I switch to BMW BLUE COOLANT.

2.) It's gotten cold all of a sudden here in Southern California. As in A LOT. I was confident in doing this a few weeks ago but summer is suddenly over. Because of this I'm worried how my distilled water dilution and flushing of old coolant would be introduced to a hot revving engine.

*I'm thinking of removing the T-Stat to ensure constant flow but I couldn't do it because it may cause old coolant spillage. So if I don't remove the T-stat, it makes me wonder how the radiator introduces cold fluid to the engine as T-Stat opens when engine gets hot. Does the radiator in some way heat the liquid before it's introduced into the engine? In general, how do BMW's in colder snowy areas do this? (You start engine, engine heats up, T-stat opens, then winter cold chilled liquid enters the engine... )

3.) To be safe, I'm thinking of letting the engine cool as much as possible between drain and fills. But I still have the same questions in #2. If anyone has done this, how long did you have to wait in between drains just using the Distilled Water Method?

4.) It's my first time doing this on a BMW. Have done it on Japanese Car. My Dad's BMW already overheated once when I was younger on our way home and he told me never put a distilled water on a hot engine. Dad is not here anymore, so I'm being very careful (or paranoid) and kind of a childhood issue (Yeah I know I need a therapist).

Appreciate any input.

[s8ilver]

I'd think you could do a "clean" block draining with some sort of rigged up funnel and hose, but yeah, otherwise it's a total mess. I even thought about drilling & tapping the block bolt with some sort of fitting to make draining a snap.

Why not just take it to a shop and let them make a mess?

[RayBallen]

I'd think you could do a "clean" block draining with some sort of rigged up funnel and hose, but yeah, otherwise it's a total mess. I even thought about drilling & tapping the block bolt with some sort of fitting to make draining a snap.

Why not just take it to a shop and let them make a mess?

Because I'm replacing the coolant pipes as well (engine block and back of the engine). My goal is if there's any spillage, especially removing the Y pipe connector at the back of the engine, it's water, not coolant. Some water spillage is allowed. I prefer to do the cooling pipes myself to save some money, especially knowing I could do it.

[jclausen]

I really think your making way to much a out this, replace the pipes fill it bleed it and if you want it flushed right and have the fluid dealt with pay an independent shop to drain and flush when your done, they have to dispose of it properly the thermostat stays closed as the engine is warming up as soon as the coolant gets to the right temp the thermostat opens and now brings the radiator in to the picture, coolant goes in to the radiator at the top gets cooled thru the core then goes out the bottom. When the thermostat starts to open it takes a while opening slowly. Just do the work and let somebody else's flush it. Unless your engines coolant passages are filled with crap you don't need to chemically clean it.

[khammack]

Searched as much as I could on the forum and on google but couldn't find a detailed discussion on this. I'm scared to do coolant flush and refill on my 97 Z3 1.9 (Part of my cooling system overhaul) due to the following reasons:

1.) Carport (non-enclosed) where I park my Z3 doesn't allow me to do a block drain or any spillage type of maintenance. Property Rules and Security guard present not too far from my carport. I have to do this as quiet and discreet as I can. So I have to drain everything through the radiator so I wouldn't spill anything. My plan is to clear out/dilute the old YELLOW COOLANT with DISTILLED WATER like many would show in YOUTUBE (i.e. ChrisFix) before I switch to BMW BLUE COOLANT.

2.) It's gotten cold all of a sudden here in Southern California. As in A LOT. I was confident in doing this a few weeks ago but summer is suddenly over. Because of this I'm worried how my distilled water dilution and flushing of old coolant would be introduced to a hot revving engine.

*I'm thinking of removing the T-Stat to ensure constant flow but I couldn't do it because it may cause old coolant spillage. So if I don't remove the T-stat, it makes me wonder how the radiator introduces cold fluid to the engine as T-Stat opens when engine gets hot. Does the radiator in some way heat the liquid before it's introduced into the engine? In general, how do BMW's in colder snowy areas do this? (You start engine, engine heats up, T-stat opens, then winter cold chilled liquid enters the engine... )

3.) To be safe, I'm thinking of letting the engine cool as much as possible between drain and fills. But I still have the same questions in #2. If anyone has done this, how long did you have to wait in between drains just using the Distilled Water Method?

4.) It's my first time doing this on a BMW. Have done it on Japanese Car. My Dad's BMW already overheated once when I was younger on our way home and he told me never put a distilled water on a hot engine. Dad is not here anymore, so I'm being very careful (or paranoid) and kind of a childhood issue (Yeah I know I need a therapist).

Appreciate any input.

I think you could use an Airlift Cooling System Leak Checker and Airlock Purge Tool.

https://www.amazon.com/UView-550000-...0407159&sr=8-1

[RayBallen]

I really think your making way to much a out this, replace the pipes fill it bleed it and if you want it flushed right and have the fluid dealt with pay an independent shop to drain and flush when your done, they have to dispose of it properly the thermostat stays closed as the engine is warming up as soon as the coolant gets to the right temp the thermostat opens and now brings the radiator in to the picture, coolant goes in to the radiator at the top gets cooled thru the core then goes out the bottom. When the thermostat starts to open it takes a while opening slowly. Just do the work and let somebody else's flush it. Unless your engines coolant passages are filled with crap you don't need to chemically clean it.

Yeah, I know. It's just the stupid no coolant/oil/automotive liquid spillage rule in my property. They're pretty strict. I'm trying to spill at the worst just water that's why the distilled water dilution method (and radiator only).

So you're saying the radiator, together some coming from the engine, warms up the liquid before it enters the head of the engine? It seems to be the case as I warmed up the car this early morning. Radiator was cold then it warmed up as the temp gauge rised, giving the indication that it does heat up the coolant before the T-stat let's it enter the engine. So it's not really a good idea to remove the T-stat in this cold weather.

I think you could use an Airlift Cooling System Leak Checker and Airlock Purge Tool.

https://www.amazon.com/UView-550000-...0407159&sr=8-1

This is great. Bleeding for just two minutes. Thanks for this.

[Tigershark48]

Make it easy and worry free on yourself and have the dealership do it. Take it in, pay the bill and drive it home. It should be done correctly and you won’t break any rules. I just had all of my fluids changed, poly subframes bushings and ceramic brake pads installed. Roughly $1k with some items provided by me and everything is perfect again. It's nice to do it yourself, but if you don't have the tools or location to do that, the dealership or a trusted mechanic is the next best thing.