Mixing different Coolants - what do you think?

[leicesterboy15]

Hi All

I am at a bit of a loss with this one, my car seems to have a coolant leak from somewhere, no evidence of it on the drive and when I release the cap it hisses as if under pressure and yet periodically i get the coolant low message and have to fill up (usually around 1 litre). Its almost as if its not a regular leak but it just periodically dumps some coolant. I had a brain wave last night and thought maybe its linked to the climate control - when I use it it dumps some coolant, is this rubbish or is it possible? The interior is not wet at all. I hope its not this!

My other problem is that while I have this problem I have to keep topping up so I top up about 5 times and then flush the whole system out and refil with coolant and water. Does it matter if I run with more coolant than I should and does it matter if two different coolants mix? Also does it matter if I run with more water than I should? What type of coolant do you recommend or doesn't it matter?

Thanks guys!

[repenttokyo]

don't mix coolants. as for how much water versus coolant you should be running, that depends on the climate you are running in. the colder it gets, the less water you want in there.

[632 Regal]

you might need a new heater auxillary pump / valve unit, mine cracked the little pump housing and was hard to see. I wouldn't mix coolants and would recommend cool blue from BMW.

[pgrindstaff]

I had a similar problem lately where I would have to keep topping off my coolant and ended up just using water. Unfortunately, last week the hose barb on my expansion tank broke but the hose managed to stay on just enough to just squirt it out the side creating quite a mess. I actually didn't realize the hose was leaking until I started filling it with water and it was leaking out just as fast as I was putting it in. Anyway, I had been running mostly water for coolant for probably a month and everything was ok, but I did a coolant flush yesterday when I replaced the expansion tank.

Your question about what coolant to use has been touched on quite a bit here and believe me, a search result will give you plenty of reading to do. I just bit the bullet and bought the BMW coolant for $20, but only bought one gallon. Like you will read, $20 isnt really that bad considering your coolant doesn't need replaced but every two years and why take a risk.

I am by no means an expert nor am I exactly mechanically inclined, but I do all of my maintenance myself with the help of this forum and many other sites. When my expansion tank broke and before I knew exactly where the coolant was coming from, one user suggested that my problem could be the heater valve or the auxilary water pump, both located on the left side of the engine bay I believe.

Unfortunately, I am not exactly qualified to offer any real help but thought I would share my experiences, hoping that they may offer somewhere to start looking.

Good luck getting your problem taken care of