So I'm not sure why but it has escaped me to do coolant flush for a few years. I'm pretty good with the rest of the maintenance. I don't know when is the last time it was done though, if ever. As I'm reading all about it I find it difficult to get clarity and thought it might be good to get a thread going on coolant flush for those not entirely sure where to start for N18 engines and others


Few questions I have:

- What is the frequency for coolant change? I've read every year, every 3-4 years, and even read that the modern coolant BMW MINI uses are one of those life time fluid (mentioned in the Bentley manual as well) So unclear?


- In the Bentley manual they are a hair short on detailed explanations when it comes to the coolant flush. They further state: “As a preventive measure, replace cooling system hoses every four years”. I thought wow. However they don’t state the hoses in question that fits under that statement? It sounds like a pita to do and change all hoses. Thoughts on this?



- It seems that there is two techniques to change the fluid. One by using an air vacuum to empty and fill (requiring an air compressor). The other to run the heat and blower fan on max. But that second method does not seem to guarantee there will not be air left in the system. How concerning is this? Is the vacuum check a must, or at a minimum highly recommended?



- Last simple one. The recommendation is to do a 50/50 mix of MINI coolant fluid and distilled water. Does any distilled water work like what one might get in the grocery store? And is it preferable to mix prior to filling?

 

When I did my thermostat, I also splurged on the vacuum tool. Soooo nice for filling. I’ve done fill and burp on older cars, and this was my first experience with a vacuum tool. When it came time to fill, I was almost giddy it was so easy. No air in the system, no burping, literally just fill and go.

I bought two jugs of distilled water from the store. As long as it says distilled water in the label, good to go. Mix before filling.

You could probably get away with every 4-5 years for coolant changes. Or every 50,000 miles. The hoses will probably be good for 10 years or so. When I did my thermostat, I bought the Mishimoto silicone hose set and replaced just the ones from the kit. Any other rubber hose in my engine bay is still original to the car, and I haven’t had any issues.

 

This is helpful. I'll try to find some video to get myself more familiar with vacuum tool... It would have been great for someone to have done a DIY. I'll do some dinging.
See, your numbers are more what I would expect. We got 70k miles on the MINI and about 9 yrs of ownership so it doesn't sound horrible. It might have been done once. I need to find my service records...

Silicon hoses are great though they are also more prone to cuts. More fragile to tare and can expand more easily. I like using them for air intake. I don't know how I feel about using them for cooling fluids... hmmm(?)

 

Is this essentially how it works?

 

That’s it right there!

 

Dam, now I have to see about getting a air compressor or not, which I've been avoiding to do all these years due to the lack of storage space :p

 

To drain the coolant I'd rely upon gravity. Even if there is a drain valve you might have to disconnect a hose to ensure a good portion of the old coolant drains. Of course it is possible the factory manual *calls* for the use of a vacuum lift system to remove the coolant. The cooling system may just not be conducive to a gravity drain.

A vacuum lift is preferred for filling. Using gravity to refill can work but I have read the recommendation is to arrange to have the coolant tank higher than the rest of the car. After filling you will still need to then start and run the engine for a bit to get the coolant hot enough to open the T-stat and eliminate any air pockets. If there are any the coolant level will be low after you have got the engine hot. You wait until the engine cools down and top up the level then repeat.

As an aside, for one of my cars that really required a vacuum lift system the factory manual instructions for ensuring the cooling system was completely refilled not using a vacuum lift system bordered on engine abuse. For this reason for cars that required a vacuum lift to properly fill the cooling system I had the coolant drained and refilled at the dealer.

For decades -- based on the advice of auto techs back then -- for my vehicles I have changed the coolant around every 4 years. Changed it or had it changed. The additive package degrades and this can negatively affect water pump seals, hoses, and even the thin walls of the radiator and heater core.

With regular coolant changes even with one car that I drove 16 years and to 317K miles I have never had to replace a radiator/heater hose. The water pump lasted to 172K miles. I would not replace hoses unless they showed signs of needing replacement. One check is with the engine warm (but not running) give each hose a squeeze. Grip the hose so your finger tips are pressed against the underside of the hose. Grip the hose close to where it connects to the water pump, block, radiator. Give the hose a good squeeze and try to push your finger tips through the hose. A healthy hose will be firm. A hose due to be replaced will have you feeling like you could push your fingers through the hose. My auto tech buddies told me if I find one hose in need of replacement to replace all hoses, radiator, and heater core hoses.

Grocery store distilled water -- be sure the label reads distilled water and not "mineral" or "spring" water -- is ok to use. Mix the anti-freeze/distilled water 50/50.

Added: While I have never encountered a reason to replace coolant hoses in 4 years I'm loathe to go against what MINI calls for in this regard. I have not yet owned a MINI (or BMW) longer than about 2 years (my 2018 JCW). So I have never had to deal with servicing a car 4 years old or older. When the time comes I'll see what the techs advise. While Porsche at the time at least didn't call for preventative hose replacement I considered having it done to a car with big miles (>200K) on it. Techs advised me with regular coolant changes -- which this car had had -- they had never seen a hose needing to be replaced. They advised to leave the hoses alone. I did and when I sold the car at 16 years old and with 317K miles the hoses were fine. The water pump that had been replaced at 172K miles was fine. That is the replacement water pump had 145K miles on it and at least when I sold the car was showing no signs of any issues.

So while I may think the 4 year hose replacement as a preventative measure a bit over the top I can't advise you to go against MINI in this regard.

 

Thanks @RockC Those are awesome tips!

 

We bought the car new and have had it for 10 years this August. So far it's been a good car. We broke down once on a long road trip of course with reason somewhat unclear. Some module was fried (and under some extended warranty). And we had to change the automated spoiler. We also had a service belt that skipped a tooth a few month after it was changed (go figure). Work was done not long before all this power loss issue. The belt cause the engine not to run smoothly. I've never fully understood why it all happened around the same time. We got it all fixed. But so far the rest has been trouble free and the engine seems to be running okay. With about 76k miles we don't have a tone of miles on it so time will tell...
I like to be on the safe side without changing parts unnecessarily when there is nothing wrong with them. Along with other maintenance items I do my oil changes regularly and always check the fluid levels. The car is parked indoor the majority of the time when not used. I think it helps a tone making rubber and plastic last a bit longer...

 

Good info on the vacuum method......