Coolant loss

[631twentyeighteye]

I've had to top my reservoir tank off 3 times since i got the car in july 2012. Once six months after i got it, another time on thanksgiving 2013 and then again a few days ago. the car had 25.5k miles when i got it, and i'm just over 55k miles now. it's a 2010.

Now I haven't noticed any large puddles on the ground below the car nor have a noticed any in the oil. my next oil change is in 2 thousand miles and i'll be sending a sample to blackstone labs for analysis.

I've found on e9x groups that people have had to top theirs off here and there but usually with long time spans between somewhat similar to my experience.

That being said, I've noticed moisture on the ground below the engine bay somewhat intermittently. I guess my question is what would you personally suspect to be leaking/causing the issue. I haven't had any overheating issues so i don't necessarily think it's the water pump, but i suspect i may have a cracked reservoir/ a leaky or split hose somewhere. Any help is greatly appreciated.

[TheSt|G]

M54s were known to sip a bit of fluids here and there, but the N52 was such a drastic departure that I wouldn't follow that train of logic at all. In general, the N52 is known for running very cleanly. I would check the hoses as you mentioned. You could also remove the underbody panel and idle it for a few minutes to see if you notice any drips for a sense of location.

Also getting near water pump failure time...

[SuperCNJ]

Probably doesn't help you, but my N55 had one case of coolant loss too. Topped up at 10,000miles and hit minimum level at 13,500. I took it into BMW for a pressure test, no leaks or anything. So I presumed its just a characteristic of the car.

[Solo_M_Tech]

He has the n52. Coolant doesn't just disapear at that rate. It's either leaking or being burned. I would get the cooling system pressure tested.

[JimD]

A test isn't a bad idea but a little bit of coolant loss may not be worth the aggrivation to find. It could be a leaky hose. I've also wondered if it isn't possible it just expands enough when the engine is hot to push a little out the overflow of the expansion tank reducing the level. I must admit, I don't even check mine. I'll have to do that soon.

[Solo_M_Tech]

A small leak only gets worse. Why risk it for a half hours labor? If the coolant pressure doesn't drop you don't have a leak, if it does, you need to find it. Just my.02 cents. I wouldn't ignore this on my car.

[631twentyeighteye]

No intentions of ignoring it just trying to narrow it down as much as possible so i can minimize mechanic costs. I haven't done anything about it as of late because it's so damn cold and it's just plain awful to wrench on anything when its cold.

I'm thinking i might have cracked or split a hose or made the existing one worse when i did my header install. If i can't find any sure signs of a leak anywhere i'll bring it to get pressure tested.

One thing i have noticed is that the more the car sits, the more coolant is lost.. In the winter i drive my car significantly less and that's usually when i have to fill it up. I've never had to top it off when i drive it daily. I'll be commuting to and from school again soon so i'll keep an eye on whether or not this is true. Also i'm not sure if it makes a big difference or not, but the 2nd time i topped it off on thanksgiving i didn't have any coolant at my house so i went to my buddy's house down the road to top it off.. So i wasn't able to fill it while it was cold. the 3rd time i made sure to top it off when it was still stone cold.

[andrey_gta]

I've had coolant disappear, but that only happened once during the first summer after I purchased the car.
So I think you may have a maintenace issue & a water pump warning. If its not a leak you should start shopping around.

I feel for you, you have done all the cool things we can do to the car and now your running into issues with catless cel, exhaust welds disappointment and now this. Really hope you sort it out.

[631twentyeighteye]

It's been a bit frustrating that's for sure. The o2 SES has been fixed with the new primary which was thankfully easier than i was expecting. To be honest, the coolant loss doesn't have me very worried at all because i know the BMW computers are smart enough to shut themselves down should they determine they're going to overheat. I also keep a couple bottles of water and my BMW coolant jug with me everywhere i go.. Just in case LOL.

I'll probably just end up bringing it to a shop to try and figure out what's going on. I hate diagnosing a system that's so crucial to the car's welfare.

[TheSt|G]

Originally Posted by JimD

A test isn't a bad idea but a little bit of coolant loss may not be worth the aggrivation to find. It could be a leaky hose. I've also wondered if it isn't possible it just expands enough when the engine is hot to push a little out the overflow of the expansion tank reducing the level. I must admit, I don't even check mine. I'll have to do that soon.

That would imply it was overfilled. The cold fill line exists for a reason.