Coolant Leak

[///F80M3]

I have coolant leak but I cant seem to find where its leaking. I topped off both tanks and two days later they're both empty. There's no coolant marks anywhere and no dripping under the car.

Car doesn't have warranty anymore and I thought it could be the intercooler leaking internally but both reservoirs are empty so idk

[FriedPiston]

Disappearing coolant is never good. Are there any white smoke coming out of the car?

[///F80M3]

Originally Posted by nars3000

Disappearing coolant is never good. Are there any white smoke coming out of the car?

Haven't noticed it. Will it smoke on idle?

[LAKERS333]

Originally Posted by ///F80M3

Haven't noticed it. Will it smoke on idle?

Check your top mount charge air cooler/intercooler. You could possibly have a busted intercooler and fins have gone bad inside. Leaks would be internal also. Your car should also be going into limp mode if its getting too hot.

I'm tuned and recently had same issue and the intercooler on top of engine went bad and I tried finding the stock one and no one had in the country, ended up upgrading to the CSF intercooler. Its a nice upgrade and probabaly needed one for higher boost with tunes.

[///F80M3]

Originally Posted by LAKERS333

Check your top mount charge air cooler/intercooler. You could possibly have a busted intercooler and fins have gone bad inside. Leaks would be internal also. Your car should also be going into limp mode if its getting too hot.

I'm tuned and recently had same issue and the intercooler on top of engine went bad and I tried finding the stock one and no one had in the country, ended up upgrading to the CSF intercooler. Its a nice upgrade and probabaly needed one for higher boost with tunes.

Dealer pressure tested and replaced both coolant tanks. Now engine coolant isn't leaking anymore but intercooler tank was empty the next day. I'm going to remove the intercooler tomorrow to check for coolant in throttle body pipe. Is there any way to test the intercooler for leaks?

[amw896]

Personally, I would stop driving it and get an oil analysis done asap. Sounds like your head gasket is pooched. If this is the case, you should definitely be able to see white smoke and even the smell of your exhaust on idle will be different.

[TurboM]

The air charge and engine cooling systems are separate. Figure out which is losing coolant first then start your investigation.

I highly, highly doubt your head gasket is blown as mentioned above. If it was, you'd either be mixing coolant with oil or burning coolant in the combustion chamber(s). Both would be very evident and a huge problem.

FYI, burnt/hot coolant has a sweet smell to it. Kind of smells like pancake syrup.

[///F80M3]

Originally Posted by TurboM

The air charge and engine cooling systems are separate. Figure out which is losing coolant first then start your investigation.

I highly, highly doubt your head gasket is blown as mentioned above. If it was, you'd either be mixing coolant with oil or burning coolant in the combustion chamber(s). Both would be very evident and a huge problem.

FYI, burnt/hot coolant has a sweet smell to it. Kind of smells like pancake syrup.

Now only intercooler tank is losing coolant. Engine coolant is fine after replacing leaking reservoir.

[Dphan2007]

Originally Posted by ///F80M3

I have coolant leak but I cant seem to find where its leaking. I topped off both tanks and two days later they're both empty. There's no coolant marks anywhere and no dripping under the car.

Car doesn't have warranty anymore and I thought it could be the intercooler leaking internally but both reservoirs are empty so idk

I found out that this is a known from someone at BMW. He fixed the issue himself. There's a coolant line somewhere in the charge pipe or intake. I know this issue sucks but he told me to take the car in once I noticed this issue. He told me that BMW is aware of this. Sorry that your car is out of warranty. Let me know how this goes.

Thanks!

DMAN

[///F80M3]

Originally Posted by Dphan2007

I found out that this is a known from someone at BMW. He fixed the issue himself. There's a coolant line somewhere in the charge pipe or intake. I know this issue sucks but he told me to take the car in once I noticed this issue. He told me that BMW is aware of this. Sorry that your car is out of warranty. Let me know how this goes.

Thanks!

DMAN

Can you be a little more specific and how did he fix it? I don't see any coolant visibly leaking. Thanks

[heckyeahbro69]

If the intercooler tank keeps loosing coolant, it's likely the intercooler is leaking internally and the coolant is ending up in the combustion chambers. To find out if that is the case, you have to remove the charge air pipe from the 'cold' side of the intercooler and pressure test the cooling system. Once you have pressure on it, check for coolant leaking. You will probably see some residue in the pipe also. This is not common, but it does happen on s55 and b58.

[DavidGP]

I had an intercooler leak and had dealer replace under warranty. Noticed that the reservoir was empty after filling it over and over. Car went into limp mode with drivetrain malfunction warning appearing intermittently. Leak was internal and went into the combustion chamber. Take to dealer ASAP, not good to drive it like this.

Hope this helps

[amw896]

DavidGP -- How did they remedy this for you? Isn't the motor pooched at this point?

[DavidGP]

Originally Posted by amw896

DavidGP -- How did they remedy this for you? Isn't the motor pooched at this point?

They did a pressure leak test and discovered the IC was leaking internally. The coolant pools in the U-shaped tubing going into the intake and doesnt quite make it to the intake. If it does it comes out the exhaust rather quickly. I thought it would have caused all kinds of issues with mixing in the oil etc etc but apparently not, it just goes out of the exhaust. The tech mentioned it could have caused damage if allowed to go on that way for a while and we were fortunate to bring it in when we did.

The way I discovered this was the drivetrane malfunction warning and checking the IC reservoir and noticed it was low. Topped it off and the next day it was low again. Part had to be sent from Germany and car was in the shop 2 weeks waiting.

Hope this helps

[amw896]

That's nuts! Glad you got it sorted! Hope this isn't common.

Originally Posted by DavidGP

They did a pressure leak test and discovered the IC was leaking internally. The coolant pools in the U-shaped tubing going into the intake and doesnt quite make it to the intake. If it does it comes out the exhaust rather quickly. I thought it would have caused all kinds of issues with mixing in the oil etc etc but apparently not, it just goes out of the exhaust. The tech mentioned it could have caused damage if allowed to go on that way for a while and we were fortunate to bring it in when we did.

The way I discovered this was the drivetrane malfunction warning and checking the IC reservoir and noticed it was low. Topped it off and the next day it was low again. Part had to be sent from Germany and car was in the shop 2 weeks waiting.

Hope this helps

[///F80M3]

Originally Posted by DavidGP

They did a pressure leak test and discovered the IC was leaking internally. The coolant pools in the U-shaped tubing going into the intake and doesnt quite make it to the intake. If it does it comes out the exhaust rather quickly. I thought it would have caused all kinds of issues with mixing in the oil etc etc but apparently not, it just goes out of the exhaust. The tech mentioned it could have caused damage if allowed to go on that way for a while and we were fortunate to bring it in when we did.

The way I discovered this was the drivetrane malfunction warning and checking the IC reservoir and noticed it was low. Topped it off and the next day it was low again. Part had to be sent from Germany and car was in the shop 2 weeks waiting.

Hope this helps

I already ordered the intercooler and I'm going to check the pipe today. This sucks because I've been driving for weeks now with this issue and just topped off every other day. I never got any codes and initially noticed it when I happened to checked coolant. God knows how long this has been happening.

[tom @ eas]

We've seen about a half dozen cars with leaking top-mounted heat exchangers. While not too common, your situation is not an isolated case. Usually, you'll see a Drivetrain fault appear when building boost/heat, with missing coolant in the tank.

Dealer should get this rectified quickly under warranty.

[Aaaaaaaaa]

Originally Posted by tom @ eas

We've seen about a half dozen cars with leaking top-mounted heat exchangers. While not too common, your situation is not an isolated case. Usually, you'll see a Drivetrain fault appear when building boost/heat, with missing coolant in the tank.

Dealer should get this rectified quickly under warranty.

You guys see a ton of cars though right? So hopefully not too common...

[tom @ eas]

Originally Posted by pheerlx

You guys see a ton of cars though right? So hopefully not too common...

We see a ton of M3/M4s come through the doors and always engage in conversation with owners during jobs. Some we've diagnosed, other cases were just brought up during chat. Once it's diagnosed, it should be handed under warranty.

It's not too common, dealer seems to be on top of things in most cases.

[LAKERS333]

Originally Posted by tom @ eas

We see a ton of M3/M4s come through the doors and always engage in conversation with owners during jobs. Some we've diagnosed, other cases were just brought up during chat. Once it's diagnosed, it should be handed under warranty.

It's not too common, dealer seems to be on top of things in most cases.

This won't be handled under warranty for the OP and many others if tuned. This was the case for me anyways where warranty was voided. If paying out of pocket it might be a good time to just upgrade to CSF intercooler.

[tom @ eas]

Originally Posted by LAKERS333

This won't be handled under warranty for the OP and many others if tuned. This was the case for me anyways where warranty was voided. If paying out of pocket it might be a good time to just upgrade to CSF intercooler.

If modded, it depends on the dealer and/or tune being used. Every case is different.

[///F80M3]

Originally Posted by LAKERS333

This won't be handled under warranty for the OP and many others if tuned. This was the case for me anyways where warranty was voided. If paying out of pocket it might be a good time to just upgrade to CSF intercooler.

I was considering the CSF but $2k is way too much for me especially since OEM is $600. Hopefully I don't have to replace the OEM intercooler 4 times lol