[gioM5-Comp]

Hi all…
Here’s my situation folks…
I recently picked up a used 2019 M5 Competition from a main BMW dealership here in the Uk, with the handover being February 29th. Now before this, I’d done all the necessary research so I was aware of the expansion tank issue and went into my purchase with my eyes open let’s say. There were signs of previous leaking on the tank in the usual places, around the seam and some splatter but it wasn’t excessive for a 5 year old car. The car came with a full used car warranty so I wasn’t overly worried.

Six days later, I decided to take a quick look and check around the engine bay and it was obvious that it was getting worse so strait on the phone I got to BMW assistance and they sent an engineer out who confirmed there was a leak from the tank around the seam under pressure.
It went back to the dealership on March 7th who again confirmed the crack in the tank so replaced the tank under warranty and also checked the injectors and coil packs, which were ok.
All good then and I got my car back on March 12th. Been driving around a bit but nothing crazy, just enjoying the car.
Five days later on Sunday March 17th, I just opened the hood on the spur of the moment to have a quick check, and I was gobsmacked to see there were already signs of leaking on the brand new tank, with the some white crusty residue around the seam of the tank. To say my heart sank was an understatement. I drove around all day that Sunday and when I later checked in the evening, it wasn’t any worse than it looked in the morning. Not sure what my next course of action should be folks.

Do I ring up the dealership up and go full bore angry with them or do I try to have a calm and more constructive chat with them to see how we proceed from here. I just can’t get my head around the fact, a 5 day old tank is already showing signs of leaking. I genuinely thought I wouldn’t be seeing anything for the foreseeable future but would be keeping an eye on it just in case. I’ll see if I can upload some pictures of this brand new tank after only 5 days use. Am I being too fussy or over reacting at what I’ve seen after 5 days with the new tank..?
Any thoughts and advice on what I should do next and even how I should react with them over the phone, would be greatly appreciated as this has sort of taken the shine off a bit from what was supposed to be a dream car purchase.

Cheers Gio..

[S EyeLand]

I put the catch can on the tank so I don't have to worry about this. I did it last week when I replaced the tank. Do that or buy one of the billet tanks. These tanks are going to continue to have issues. It's only a few hundred for the catch to never have to worry about your engine grenading bc of a stuck injector from a leaky coolant tank.

[gioM5-Comp]

Originally Posted by S EyeLand

I put the catch can on the tank so I don't have to worry about this. I did it last week when I replaced the tank. Do that or buy one of the billet tanks. These tanks are going to continue to have issues. It's only a few hundred for the catch to never have to worry about your engine grenading bc of a stuck injector from a leaky coolant tank.

Hi there
I hear where you’re coming from and I would go down either of those routes in a heartbeat. My only issue is that, I can’t just do that off my own back without informing the BMW dealership first as I wouldn’t want to void my used car warranty if they deemed it as a none BMW modification. That warranty could potentially prove invaluable going forward. It may be worth mentioning to them that there are these two aftermarket solutions though and see what their thoughts are on it…

[GTTC]

Originally Posted by gioM5-Comp

Hi there
I hear where you’re coming from and I would go down either of those routes in a heartbeat. My only issue is that, I can’t just do that off my own back without informing the BMW dealership first as I wouldn’t want to void my used car warranty if they deemed it as a none BMW modification. That warranty could potentially prove invaluable going forward. It may be worth mentioning to them that there are these two aftermarket solutions though and see what their thoughts are on it…

BMW would have to prove the catch can caused the issue, which is obvious that it does not (prenty of examples). I installed mine as well. With that said we are saving BMW anywhere between $400-$50K+ in repairs.

[gioM5-Comp]

Originally Posted by GTTC

BMW would have to prove the catch can caused the issue, which is obvious that it does not (prenty of examples). I installed mine as well. With that said we are saving BMW anywhere between $400-$50K+ in repairs.

I hear what you’ve saying but I think persuading BMW to agree to that could prove quite hard. A strange stance to have really, when you think they’re not prepared to permanently solve the issue themselves.

[pmsteinm]

OP, you should unscrew the cap and take a look under there. Does it look like the leak was coming from the cap? There is a channel from the cap that allows the fluid to leak along the seam and looks like a failed tank. I had this on my car after they overfilled after a leak test. ISTA tells the tech to overfill after doing the coolant, which depending on temperature changes can cause it to blow off under the cap. Since they just put a new tank on, I recommend you clean everything up, make sure the fluid is not above the max line, and keep an eye on it. Most likely it leaked from the cap and not the tank.

[gioM5-Comp]

Originally Posted by pmsteinm

OP, you should unscrew the cap and take a look under there. Does it look like the leak was coming from the cap? There is a channel from the cap that allows the fluid to leak along the seam and looks like a failed tank. I had this on my car after they overfilled after a leak test. ISTA tells the tech to overfill after doing the coolant, which depending on temperature changes can cause it to blow off under the cap. Since they just put a new tank on, I recommend you clean everything up, make sure the fluid is not above the max line, and keep an eye on it. Most likely it leaked from the cap and not the tank.

Hiya…
Apparently they replaced the tank and the cap I was told. There is clear signs of dried white crusty coolant around the seam of the tank. Not so much in and around the cap when I looked. You say there’s a channel from the cap that allows fluid to leak along the seam…? Is that channel on the inside of the cap or the outside of the cap..? Only asking because with the coolant being around the outside of the seal, I would automatically of assumed it’s being forced out through the the seam of the tank…or I’m I getting it wrong…? Does anybody have a picture of this channel from the cap so I know what I’m looking for…?
Just to add to what I’ve said. With the cap being over to one corner of the tank, would the channel you mentioned that allows the coolant to leak along the seam a resemble a failed tank… would it cause it to leak all the way around the seam or just focused in one area..? I can see what seems like coolant leaking all around most of the seam…
Any information would greatly be appreciated

[pmsteinm]

Here is what my overfill looked like. I think the fluid moves along the seam because of capillary action:


You can see the channel above and to the right of the yellow arrow. This picture is after I cleaned up, but that whole area was filled with white crust.


This is how much extra I extracted (after who knows how much leaked):


After this leak things seem good. My theory is the overfill leak "lubricated" the Orings on the cap enough where now it no longer leaks.

In any event every time I wash the car I pop the hood to clean the engine bay and check for white residue on the tank.

[gioM5-Comp]

Originally Posted by pmsteinm

Here is what my overfill looked like. I think the fluid moves along the seam because of capillary action:
Attachment 3412871

You can see the channel above and to the right of the yellow arrow. This picture is after I cleaned up, but that whole area was filled with white crust.
Attachment 3412869

This is how much extra I extracted (after who knows how much leaked):
Attachment 3412870

After this leak things seem good. My theory is the overfill leak "lubricated" the Orings on the cap enough where now it no longer leaks.

In any event every time I wash the car I pop the hood to clean the engine bay and check for white residue on the tank.

Wow.. that to me seems quite excessive. The pictures I put up in my first post don’t seem quite as much as that. So you’re saying there’s a good chance that if it was overfilled by whatever amount then that could of vented out that channel and made its way around the seam of the tank…? And maybe after it’s shed it’s excess then it should or could settle down..? I wouldn’t of thought of that in a million years my friend but then again, I’ve never owned a car of this calibre before. It doesn’t excuse BMW for the bad design and location of the tank. If it does prove to be like you’ve said then, as it does make sense, then it would make me feel a whole lot better. I will say though, when I spotted it Sunday morning, and then spent most of the day driving, when I returned home in the evening and checked again, it didn’t seem as it had gotten any worse.
Maybe they overfilled, like you suggested and what I saw was the excess that has been vented..

[pmsteinm]

Right, it probably just flowed around the tank because it "sticks" to the lip. I flushed the mess with distilled water (mainly to clean the injectors just in case) and cleaned every spot I could find. Then I went back after it dried and cleaned some more (because as soon as you get the white wet it disappears even though you maybe didn't wipe it all off). It took a few more cleanings before I stopped spotting new spots (different lighting, angle, etc).

By car of this caliber I assume you mean "German Engineering" which really means "overly complex and elegant solutions to questions nobody asked".

Don't get me wrong, I love this car and it is my favorite. But sometimes the Germans just make stuff complicated that doesn't need to be. And seriously, how hard is it to make a robust cooling system? They have only been used on engines for over a century.

[gioM5-Comp]

Originally Posted by pmsteinm

Right, it probably just flowed around the tank because it "sticks" to the lip. I flushed the mess with distilled water (mainly to clean the injectors just in case) and cleaned every spot I could find. Then I went back after it dried and cleaned some more (because as soon as you get the white wet it disappears even though you maybe didn't wipe it all off). It took a few more cleanings before I stopped spotting new spots (different lighting, angle, etc).

By car of this caliber I assume you mean "German Engineering" which really means "overly complex and elegant solutions to questions nobody asked".

Don't get me wrong, I love this car and it is my favorite. But sometimes the Germans just make stuff complicated that doesn't need to be. And seriously, how hard is it to make a robust cooling system? They have only been used on engines for over a century.

I’ve owned proper M cars in the past ( E36 & E46 M3’s ) but never a 4.4ltr V8. The M5 Competition is on a totally different level compared to those cars and like you, it’s probably my favourite car to date that I’ve owned, albeit excluding this specific issue. I get the idea of having that channel on the tank to vent any excess coolant but surely they could of designed a channel that would vent any excess coolant away from any critical parts by simply having some kind of hose attached which could have easily been routed down and away, where it would cause the least harm.

Before I left work, I quickly unscrewed the cap and the threads were completely caked in dry white coolant. Also, despite what’s already been vented from the tank, when I shone some light down the tank to look at the level, it was clearly still showing a coolant level a few mm above the MAX level. Obviously it seems to hard for the BMW technicians to fill the tank with the correct amount of fluid….!!

I would still like my dealership to have a look at it and to that end I rang them up 5 times throughout the day and 5 times, whoever I needed to speak to wasn’t available but was promised a call back, which never happened. Typical BMW customer service then…!!
Honestly, I feel I’ve probably learnt more off you and everyone else that have replied here about the tank issue, than any of the so called BMW tech geniuses….!!

[pmsteinm]

Originally Posted by gioM5-Comp

Before I left work, I quickly unscrewed the cap and the threads were completely caked in dry white coolant.

Mine was exactly like that. You are correct that the dealer should fix this, but you have to decide if it is worth the hassle of going there, waiting, hoping they do it right, etc.

I see why they run into trouble because of this (straight out of ISTA):


I don't know if is the same in the UK, but in the US there is no requirement for a dealer "tech" to have any training or experience. So sometimes you get a person who knows what they are doing (and maybe respects and appreciates cars), other times you get the new guy, or an experience doofus or wanker, who either doesn't follow directions or does even when they are incorrect or not applicable. The directions above are for when you completely drain the coolant. In our cases for a tank replacement that is not the case so the above probably should not apply.

I miss the days with my CTS-V when I was under warranty and I only had 1 tech work on my car, and he always did a great job. The one time he was unavailable for an alignment I had to take the car back to get it fixed because the other guy messed it up. Then like all top people in a given field he moved on to other things. But by then I was out of warranty and would do everything myself.

[gioM5-Comp]

Originally Posted by pmsteinm

Mine was exactly like that. You are correct that the dealer should fix this, but you have to decide if it is worth the hassle of going there, waiting, hoping they do it right, etc.

I see why they run into trouble because of this (straight out of ISTA):
Attachment 3413206

I don't know if is the same in the UK, but in the US there is no requirement for a dealer "tech" to have any training or experience. So sometimes you get a person who knows what they are doing (and maybe respects and appreciates cars), other times you get the new guy, or an experience doofus or wanker, who either doesn't follow directions or does even when they are incorrect or not applicable. The directions above are for when you completely drain the coolant. In our cases for a tank replacement that is not the case so the above probably should not apply.

I miss the days with my CTS-V when I was under warranty and I only had 1 tech work on my car, and he always did a great job. The one time he was unavailable for an alignment I had to take the car back to get it fixed because the other guy messed it up. Then like all top people in a given field he moved on to other things. But by then I was out of warranty and would do everything myself.

If they blindly follow those instructions wether they just change the tank or do a complete system bleed then that just serms plain crazy…!!
With regards technicians… I think it’s the same no matter where you’re from. It seems very hit and miss nowadays. I’ve had some great ones in the past. Main dealership ones and independent garages too. Those that were very knowledgeable were only to happy to help and would even offer me advice on previous cars advising me not to bother taking the car in as I could easily fix it myself, and proceeded to explain to me how to sort whatever problem I had myself. A good technician or mechanic, that you can trust is priceless. Unfortunately in the industry now, there seems to be a lot of wankers my friend…!!

[gioM5-Comp]

Quick update regarding my recent replacement tank. Finally got to speak to someone from my BMW dealership today. We discussed the fact that I spotted leaked coolant residue around the tank just six days after it was fitted but also the fact that in the couple of days since, it hadn’t gotten any worse either.
Is over the phone thoughts were that he thinks that the tank had just basically vented the excess coolant that was in there but they would pressure test the tank again anyway, when it came in.

My question would be, why would there be any excess coolant to vent unless they’d overfilled it…? Surely you’d think their technicians would be capable of filling the tank to the right level…!! Anyway..its going back to the dealership on Friday afternoon so fingers crossed it’ll get sorted.
I will add though, it took the service manager to intervene on the issue after I complained that I’d called five times the day before ( six if you count this morning ) and six times I was promised a call back that never materialised.
Let’s hope this brings the matter to a close and I can just concentrate on enjoying the car.

[pbonsalb]

Overfill it and there isn’t enough room for the coolant to expand when hot so the pressure builds up and the cap vents. I would assume it was overfilled. Even though dealers charge the highest rates that does not necessarily mean their work is the highest quality. Unfortunate. This is one reason I DIY.

[gioM5-Comp]

Originally Posted by pmsteinm

Mine was exactly like that. You are correct that the dealer should fix this, but you have to decide if it is worth the hassle of going there, waiting, hoping they do it right, etc.

I see why they run into trouble because of this (straight out of ISTA):
Attachment 3413206

I don't know if is the same in the UK, but in the US there is no requirement for a dealer "tech" to have any training or experience. So sometimes you get a person who knows what they are doing (and maybe respects and appreciates cars), other times you get the new guy, or an experience doofus or wanker, who either doesn't follow directions or does even when they are incorrect or not applicable. The directions above are for when you completely drain the coolant. In our cases for a tank replacement that is not the case so the above probably should not apply.

I miss the days with my CTS-V when I was under warranty and I only had 1 tech work on my car, and he always did a great job. The one time he was unavailable for an alignment I had to take the car back to get it fixed because the other guy messed it up. Then like all top people in a given field he moved on to other things. But by then I was out of warranty and would do everything myself.

Originally Posted by pbonsalb

Overfill it and there isn’t enough room for the coolant to expand when hot so the pressure builds up and the cap vents. I would assume it was overfilled. Even though dealers charge the highest rates that does not necessarily mean their work is the highest quality. Unfortunate. This is one reason I DIY.

Hiya..

So, my car went back to the dealership on Friday 22nd of March to investigate the coolant tank again. As you guys already suspected, the tank had indeed just vented some excess coolant because it had been slightly overfilled and the residue I could see was that. They pressure tested it just to be safe and confirmed the tank is ok.
Thankfully this time, I managed to speak to a technician who seemed pretty clued up about it and came out personally to see me to explain it all. He admitted that someone had overfilled it slightly but there was still no excuse for it and was very apologetic. He managed to strip it down some and clean up all around it too.
He also seemed to agree about the tanks poor design and inevitable positioning.

I tend to go with my gut instincts when it comes to people and to honest, this particular technician seemed very genuine to me. I asked him for his name for future reference. Always good to have a point of contact I felt.
Hopefully this puts this issue to bed but I still keep checking it just in case.
Thanks everyone for all your input with this. Every day’s a school day hey…

Cheers Gio