I am about to change the coolant in my MCS and before I started I wanted to know if there are any secrets or shortcuts. It appears the lower air deflector is going to have to be removed to access the drain, is this accurate? Also, when I did a search on this subject, there seems to be many opinions on what coolant is best, what's the general school of thought on this? Thanks!!

 

you wont get a lot to drain out, almost exactly one gallon. there are 2 vent ports to loosen to assist drain and refill. one is back by the battery (in a base model, low down by the heater lines) and one is RF by the radiator top hose. they're black plastic. unscrew them 3-5 turns to help drain entrapped fluid. when refilling, have both loose and watch the front one as you fill. when it leaks, close it and keep refilling until the back one leaks. then close it and refill to the top of the pressure cap, and then fill the over flow half way. watch it for a week but you should be good to go. note, just snug those vent ports, dont brake them!

 

On the MCS, there is only one bleed screw. It's on the upper radiator hose and easily accessible. To drain it, you will have to remove the air deflector but that's only a few screws. The hardest part is getting the lower radiator hose clamp off. You can do it with regular plyers but some 90 degree plyers would help a lot.

1st, remember to turn the heater control to full heat before you drain the coolant. When you get the lower radiator hose off, the coolant that comes out will only be from the expansion tank and radiator. To my knowledge, there is no engine block drain so your not going to get all of it out. Also, when I filled the coolant back up, it didn't drain into the system like the manual said it would. It makes me think the manual expects the system to be at operating temperature and the thermostat open. When I did it cold, the coolant I put in the expansion tank didn't drain down into the radiator. I had to start the car up and let it warm up before the coolant would start running through the system. If you want, you can completely remove the bleed screw and get a small funnel to get coolant into the upper radiator hose. Get a spotter to watch the coolant temp gauge after you start the car just in case. I started overheating a tad bit and shut her off because I didn't have the expansion tank cap on and the system wasn't able to pressurize.

After you get the coolant in and the expansion tank cap is on (and engine running), open the bleed screw and you'll get a mix of air and coolant come out. Once it's pure coolant, close it up. Drive it around for a while and then re-bleed it with the car still running. Keep doing this until only coolant comes out.

It was a little hectic for a couple moments but not bad for my first time doing it. I used the new Prestone All Makes All Models which is silicate free, etc. Since you won't get all the coolant out, my plan is to drain it every two years so there isn't much old stuff in the system by the time it starts going bad.

 

I bought the BMW brand coolant from a bimmer dealer, and ingrediants are exactly the same as MINI's. I understand an important aspect of the coolant is that is phosphate (sp?) free... I would recommennd using only MINI or BMW coolant..

Curious, was the coolant reasonably clean? How did it look? my january 2005 coolant looked murky, kinda like a cess pool, and the dealer changed it for free.. however, it still looks crappy.

Coolant in my 1999 volvo looks nice and clean, which is unlike the MINI's

I assume that is because only a small portion of the coolant came out when the dealer did the freebie coolant change. I plan to change it again to get clean fluid, still haven't had time, and am concerned that murphy's law will happen and cause me grief if I do it myself...

 

I've had the stealership do mine a couple of times under warranty because it looked brown. It's getting better. I'm doing a radiator and silicone hose swap so I will also be doing my coolant. I am going to go with OEM on this one. What I'm going to do is put ionized water in and run it, then flush it, refill with water and do the same process until the fluid is clear (from the block). Then do a 50/50 mixture in the end.

 

sounds like a plan, only thought is that if you put in water only to flush it, then your ratio may be off, as the only water mixture put in will remain in the block, when you add your 50/50 mix, it isn't the right ratio

I haven't done it yet, but it seems the only right way to do it is to drain it, then mix up a batch of 50/50 distilled/bmw coolant, fill it, run car to circulate, and then drain again... then fill again with 50/50 mix which hopefully will have gotten out most of the cess pool appearance... only problem is that this requires 2 gallons at $25 each

My only other thought, is to do nothing, as this cess pool appearance isn't really a problem, as long as coolant is new....

 

there are 2 blleder screws on a MCS and i'm pretty sure there are 2 on the MC also. the one on the S is a small 8mm gold colored screw way down near the thermostat. all you need to do is pour coolant into the tank and with the screw open watch for all the air to get out. then of course close it and then bleed the other screw. i have had best luck with a cooking baster. preferrable the kind that have the brown resivour and the black tube. the tube is the perfect size to fit into the bleeder screw hole. then you just suck in the hole with the baster until coolant comes out. i think that pouring coolant inot the bleeder screw hole would prolly work but i would think you'd run better chances of creating an air pocket. and technically ther is a block bleeder screw but it is behind the starter. and pretty much impossible to get to with the starter on the car. i usually just get as much of the air out with the bleeder screws then let it run for a bit or untill it know it can sit and run and not over heat then i just go drive it and try to keep the R's up a bit to keep the coolant circulating and try and get all the air out that might be left in the system. then once it has cooled off i top up the coolant if needed.

 

Many Car Factories now put in a couple of leak sealer tablet when they fill the coolant during manufacturing. It saves them hassles of small leak resolution in the cooling system. It depends on the Car Company, the Factory location, the Parts supplier and parts batches, etc. The murkyness is the coolant leak-stop tablet effect. Flushing the coolant removes this short-cut stop-leak from the system and makes the coolant much prettier!

NOTE: The coolant stop leak does not cause any cooling problems and has some water pump lubricant advantage.:smile:

 

Thanks ewoster for the info... makes sense... also makes me realize that obsessive car care, or worrying can make things worse if fixing something not really broken... I'll save my gallon of bmw rad fluid and use it to change the fluid after 2 years....

 

If MINI uses this leak sealer, that could have been the glob of vaseline like material I found floating in my reservoir bottle when the car was pretty new. Since then, the fluid has quickly turned nasty brown looking like a blown head gasket. Time to have it change at my next service.