[cmyk]

A couple weeks ago I smelled coolant inside the car. A day or 2 later I got a low coolant light, so I topped it off with distilled water and made an appointment with the dealership to have it checked out. Dealership checked all hoses, checked water pump, etc, did a pressure test and came back with the dreaded "Could Not Replicate Problem." This is actually the second time I've brought it to the dealership to have the cooling system checked out -- the first time was about 7 or 8 months ago for the exact same issue (again "Could Not Replicate Problem / No Issues Found."). Whatever the "problem" was that time, it completely disappeared after that dealer visit, only to return this month out of the blue.

I'm not seeing any codes and I'm not overheating, but my coolant is going somewhere, especially if I can smell it inside the cabin (not strong and does not happen regularly, but I definitely know coolant when I smell it).

I'd really like to get this sorted out. After having the dealership look at it twice and not find a single issue I'm starting to wonder if I'm going crazy. I may take it to an indy for a second opinion, or start checking things myself. Any advice?

[3s4u2]

Was your heater on when smelled coolant inside the car?

[cmyk]

Originally Posted by 3s4u2

Was your heater on when smelled coolant inside the car?

No, it wasn't. We are still using our AC here in Texas lol

Although your question did make me realize that the issue has only occurred when the weather is cooler. The day I smelled coolant a couple weeks ago it was in the 60s. As soon as it warmed up the symptoms disappeared.

[TheJoy]

I've been having the exact same problem with my Jeep for about two months now. I smell coolant through the ventilation. I'm not low on coolant, and there's not a leak anywhere to be found. I think it has to be a minuscule leak in heater core.

[cmyk]

I thought heater core, too (have dealt with that in previous cars). I've checked for all the other symptoms (heater not blowing as hot as it should, wet spots on the carpet, etc) and have found nothing. My SA said they did a pretty thorough check and that the system held pressure perfectly. Really odd.

[Dark_Knight_335]

Yeah I get that too sometimes- not sure. Maybe it's when I drive hard.
Do you have an N55 or N54?

I have a Dinan stage III with an upgraded intercooler and oil cooler- not sure if that has anything to do with it.

[cmyk]

Originally Posted by Dark_Knight_335

Yeah I get that too sometimes- not sure. Maybe it's when I drive hard.
Do you have an N55 or N54?

I have a Dinan stage III with an upgraded intercooler and oil cooler- not sure if that has anything to do with it.

N54. I have a bunch of mods, too, but nothing that should affect the cooling system. I've noticed the issue with and without mods (first time it happened was a couple months after I bought the car when all I had was DCI and Cobb).

[Joe-]

Originally Posted by cmyk

N54. I have a bunch of mods, too, but nothing that should affect the cooling system. I've noticed the issue with and without mods (first time it happened was a couple months after I bought the car when all I had was DCI and Cobb).

Coolant Reserve tank!, It's actually a pretty easy fix, They are made of plastic and with lots of heat and cold tend to hairline crack and cause a slow leak, ironic when the coolant heats up and runs through this thing, It will create a slight seal, but when the coolant cools (Un-expands) it leaks.

Do you know if they did the pressure test while after the engine was hot or while the engine was cold?

I had this issue on my e46, dealership couldn't figure it out, I just kept adding coolant, eventually, the hairline crack turned into a massive crack and I came out in the morning to a car with 0 coolant.

No leak during load but leak when cold.

GL. I suggest they remove the coolant reserve and fully inspect for cracks.

[Joe-]

Originally Posted by Dark_Knight_335

Yeah I get that too sometimes- not sure. Maybe it's when I drive hard.
Do you have an N55 or N54?

I have a Dinan stage III with an upgraded intercooler and oil cooler- not sure if that has anything to do with it.

On a 2011 you shouldn't be having this problem.

[Dark_Knight_335]

Thank you Joe.

[Joe-]

Originally Posted by Dark_Knight_335

Thank you Joe.

NP with you though I would recommend them checking the same thing, though it's unlikely since the age of the car, but you never know.

[MrQuickR1]

Look around all over on the inside of the engine bay, coolant hoses, water pump area, thermostat, etc... If there is any coolant spilling out or leaking, you will see a white powder like residue. That is coolant after it has dried or exposed to air or whatever. If you unscrew your resvoir cap, you should see some on the underside of the cap. Be sure the bleeder screw on the resevoir tank is also closed snug tight...do not force tighten it as it can break.

[cmyk]

Originally Posted by Joe-

Coolant Reserve tank!, It's actually a pretty easy fix, They are made of plastic and with lots of heat and cold tend to hairline crack and cause a slow leak, ironic when the coolant heats up and runs through this thing, It will create a slight seal, but when the coolant cools (Un-expands) it leaks.

Do you know if they did the pressure test while after the engine was hot or while the engine was cold?

I had this issue on my e46, dealership couldn't figure it out, I just kept adding coolant, eventually, the hairline crack turned into a massive crack and I came out in the morning to a car with 0 coolant.

No leak during load but leak when cold.

GL. I suggest they remove the coolant reserve and fully inspect for cracks.

Thanks, that makes sense. As far as whether they did the pressure tests on a hot or cold engine, I do not know. I imagine it was warmed up, though. Judging by the fact that when I picked the car up the mpg display had made it down to ~6mpg it looks like they let it sit and idle for quite a while (maybe to warm the engine up).

This was my last service before warranty is up (I'm on my own as of Friday), so I may end up DIYing this from here. I'll have to look it up in the Bentley manual but the whole system seems fairly self explanatory from what I've seen so far.

[cmyk]

Originally Posted by MrQuickR1

Look around all over on the inside of the engine bay, coolant hoses, water pump area, thermostat, etc... If there is any coolant spilling out or leaking, you will see a white powder like residue. That is coolant after it has dried or exposed to air or whatever. If you unscrew your resvoir cap, you should see some on the underside of the cap. Be sure the bleeder screw on the resevoir tank is also closed snug tight...do not force tighten it as it can break.

Thanks. I clean my engine bay periodically and always check for any evidence of fluid leaks. I haven't noticed anything out of the ordinary, which was adding to my confusion. I'll do a more thorough check this weekend and see if there's anything I may have missed.

[RodimusPrime98]

Did you ever sort out the root cause of this issue? I am trying to sort out a similar situation with my 2007 335i. I notice the coolant smell after hard pulls or hard driving the most. I don't understand why the smell would be more pronounced for me in this situation after spirited driving. Does the coolant system pressure increase with engine RPM?

[BluesDriver]

Whatever happened to CMYK anyway??

I also have coolant slowly disappearing and the dealer says there are no leaks to be found.

Rodimus, I can only guess that after hard driving the engine is hotter and therefore the pump spins faster which in turn creates more pressure.

In other posts I've read that the coolant cap was defective and that solved the problem. I might just replace it on my own and see what happens.

[mike3000fl]

Head gasket. You smell it from exhaust. Leak down or compression test.

[thomas88162]

Originally Posted by mike3000fl

Head gasket. You smell it from exhaust. Leak down or compression test.

If you can smell the coolant, especially while the car is in motion, this is the last thing I would suspect. It has to be leaking in the engine compartment somewhere, at least I would think.

[fazman]

Originally Posted by RodimusPrime98

Did you ever sort out the root cause of this issue? I am trying to sort out a similar situation with my 2007 335i. I notice the coolant smell after hard pulls or hard driving the most. I don't understand why the smell would be more pronounced for me in this situation after spirited driving. Does the coolant system pressure increase with engine RPM?

I am losing coolant as well (I take it to the dealership every 6 months and have them top up the reservoir). an Indy noticed that one of the front coolant lines was very moist on my car... it's probably leaking from there on my car (But from what my SA said... it's not covered under CPO).

[RodimusPrime98]

Jeez, I hope it is not a head gasket! I called the local dealership and they did not seem to think it was the heater core but if it was it is 20hrs and $2900! I will look around the engine bay and the interior and see if I can see any leaks or white residue.

I forgot to mention that my low coolant light was on this week for the first time, right after I started the car. I ended up adding 1 pint of water to the reservoir. The issue has been going on long before this recent warning light and the addition of water. Also, I have never noticed a film or anything like that on the windshield.

[RodimusPrime98]

Troubleshooted this some this weekend. I don't think it is the heater core at all anymore as I don't smell the coolant at all when the heater is set to recirculate but when it is set to fresh air (non-recirculate) I can smell coolant. Stuck my noise under the hood in a few spots and unscientifically smelled coolant from the air nearest the reservoir. Other things I noticed were some wet hoses at the connection to the driver's side of the radiator (smaller 0.5-1" -ish hoses). Also, I noticed that the oil filter housing is leaking a little from the interface where the cap meets the housing. Also, the power steering reservoir was covered with what looked like leaking fluid (I assume it is the power steering reservoir, it is on the driver's side wheel well). Oil cap had milky residue but from what I have read that is normal and not the same as the oil itself being milky. No smell of coolant from exhaust.
Anyone one have any other thoughts? I will probably monitor the coolant level and wait to mention my observations when I take it in for an oil change in a month or so.

[cialz]

Happened to my x5 there was a hairline hole in the coolant reservoir so small that at regular temps it was water right. When the motor heats up it was aimed at the header cover so it sprayed in there and quickly dried up. Always got the low coolant light but never saw anything drip either. At least that smell isn't bad.