Coolant Leak on Intercooler?

[Fourleaf tayback]

Hi all!

I noticed a very slight leak of what appears to be some sort of coolant on the top of the intercooler. I had just wiped down the engine bay about five days prior so the amount seen below had leaked out over the past few days.

Any idea what this is? Is it cause for alarm?

Car is a 2016 DCT M4 with 59,300 miles.

[Kilabyte]

First check the coolant levels in both reservoirs. The stock top mount intercooler is known to fail but it happens internally. The main reservoir which is to the right of the cooler is known to split at the seam, check all around it.

[Fourleaf tayback]

Originally Posted by Kilabyte

First check the coolant levels in both reservoirs. The stock top mount intercooler is known to fail but it happens internally. The main reservoir which is to the right of the cooler is known to split at the seam, check all around it.

Is the main reservoir cap behind the intercooler towards the windshield?

How could I tell if the intercooler failed internally? I have no check engine light and the car doesn't leak a drop on the ground.

[SCS55]

Originally Posted by Fourleaf tayback

Is the main reservoir cap behind the intercooler towards the windshield?

How could I tell if the intercooler failed internally? I have no check engine light and the car doesn't leak a drop on the ground.

This is your intercooler reservoir. It generally does not have issues itself with leaking, seams weeping etc.

[SCS55]

This reservoir is your main coolant reservoir (large radiator etc) it does have a known issue of weeping/seeping at the seams. Mine (pictured) is an example of a normal one. It was replaced a few years ago at 55,000 miles.

As far as leaking internally, my situation was discovered after the fact. The previous owner had some type of internal leak which BMW eventually rectified by replacing the top mount intercooler. I found this out by noticing abnormally high coolant levels (sodium and potassium) in my first Blackstone Oil analysis after I purchased the car. Long story short, I ended up doing several oil changes then saw normal readings. I believe if you have an internal leak you would be getting low level charge coolant level warnings after repeated fillings.

[Kilabyte]

Originally Posted by SCS55

This reservoir is your main coolant reservoir (large radiator etc) it does have a known issue of weeping/seeping at the seams. Mine (pictured) is an example of a normal one. It was replaced a few years ago at 55,000 miles.

As far as leaking internally, my situation was discovered after the fact. The previous owner had some type of internal leak which BMW eventually rectified by replacing the top mount intercooler. I found this out by noticing abnormally high coolant levels (sodium and potassium) in my first Blackstone Oil analysis after I purchased the car. Long story short, I ended up doing several oil changes then saw normal readings. I believe if you have an internal leak you would be getting low level charge coolant level warnings after repeated fillings.

You'll get a drivetrain malfunction if you do a couple of hard pulls esp on a hot day, but you would feel the car pulling a bit of power before that. That was my situation. I replaced the spark plugs and the oil while replacing the top mount, which was probably not done when they serviced your car under the previous owner. To answer OP, if the level of coolant in the small reservoir behind the cooler stays the same your top mount is fine, the second you need to start adding even a small amount then you have a cooler problem. The bigger reservoir on the right is a separate loop for the cooling system. I only mentioned it because when it breaks it tends to make a mess and who knows a pinhole leak could have caused that stain on top (I doubt it but who knows)

[Fourleaf tayback]

Thanks all!

I haven't gotten any sort of drivetrain malfunction warnings yet, although I would say my spirited driving in canyons is rather tame for the S55 (rarely over 4500rpm).

Is there any long term/major damage that can result from ignoring this leak? I just had the car into an indy shop for a maintenance inspection and they didn't mention anything about this leak. Oh well, who knows if they even really looked.

[Kilabyte]

Originally Posted by Fourleaf tayback

Thanks all!

I haven't gotten any sort of drivetrain malfunction warnings yet, although I would say my spirited driving in canyons is rather tame for the S55 (rarely over 4500rpm).

Is there any long term/major damage that can result from ignoring this leak? I just had the car into an indy shop for a maintenance inspection and they didn't mention anything about this leak. Oh well, who knows if they even really looked.

Water doesn't compress, too much in a cylinder and you can hydrolock the engine.

I'd really just check the coolant level of the little reservoir behind the cooler, please tell me you've looked at least .

Edit:

Here's the original thread regarding the issue if you want some reading material:
https://f80.bimmerpost.com/forums/sh....php?t=1570544

[1FZFE]

Gents, let's first get the terminology right.

It's a charge cooler, not an intercooler. The charge cooler is known to leak on some cars. If under warranty, it may require some work to get the BMW dealer to cover under warranty. If you're out of warranty, either replace with a stock unit or go aftermarket, but avoid the fancy China parts sourced brands like CSF (popular here for some reason) if you can afford to.

The coolant expansion tank (the big one next to the cf brace on the driver side for US cars) is also known to leak at the seams (sht German design).

[N1rve]

Originally Posted by Fourleaf tayback

Thanks all!

I haven't gotten any sort of drivetrain malfunction warnings yet, although I would say my spirited driving in canyons is rather tame for the S55 (rarely over 4500rpm).

Is there any long term/major damage that can result from ignoring this leak? I just had the car into an indy shop for a maintenance inspection and they didn't mention anything about this leak. Oh well, who knows if they even really looked.

Ignoring the leak could lead to possible engine failure as water (or any huge amounts of liquid) in the cylinder is a no no and can cause hydro-lock and that is the probably the worst outcome you can face.

[aswy6]

On my last service indy shop indicated that they toped off coolant level. Can something like that indicate a leak or should i really just do a blackstone to find out?

[Kilabyte]

Originally Posted by aswy6

On my last service indy shop indicated that they toped off coolant level. Can something like that indicate a leak or should i really just do a blackstone to find out?

Just keep an eye on the level, once the top mount fails you'll be losing coolant steadily.