Coolant Leak and Cracked Overflow

[Legokcen]

Good evening. Unfortunately, I have another question for you all. I'm learning a lot about this car though!

2008, 3.0, 55K (yes, very low miles). Everything has been great and today I had an issue. I went over to a friend's shop to pick up something fabricated. While there, the car was idling and we were having a conversation for about 3-5 minutes. I turned around to turn the car off thinking we were going to talk more and when I did, I saw steam rising from around the hood. When I walked to the front of the car, I saw coolant pouring out and puddling under the driver's side. When I popped the hood, I saw that the overflow tank was cracked down the side and spewing coolant.

I've done some research and realize that this has happened to others. I've ordered the needed parts to replace the tank and cap, but am concerned that there may be other issues. I was surprised that the tank was under pressure; I'm used an overflow tank not being pressurized. I am just surprised this happened while the car was idling.

I've included two pictures. When the cap was removed and more water was put in the tank (all we had) once the engine was started, it started to gush out the top. I know now it's supposed to be under pressure.

Is there anything else I should look into? Or is this an example of old, aging plastic, and it happens to a 12 year old car? I hope it's just the overflow, but if there is more I need to do, please let me know. Pictures are attached. Thanks in advance for the help.

First picture, the overflow with the crack in the front. Coolant was spraying and coming out.

Second picture, what we saw with the engine running with the lid off.

[Cyrix2k]

The tank is usually the first to go in my experience, it's a very common problem. I'd just replace it and move on for now... Be careful with the quick connect fittings. They have o-rings inside of them and will leak if you tear one. While it is possible to replace the o-ring, it's a bit of an odd size and tough to find locally.

[Legokcen]

Thank you. From the research I've done online it seems to be a common problem with a bunch of DIY videos. I'm hoping it's good to go after this. I've ordered a new tank and cap.

[smassey321]

Pressurized overflow tanks are a European car thing. Once the new tank is in place, you may want to bleed the air from the system.

This bleed procedure works on all vehicles with the N52, N51, N52K and N54 engine, operating with electric cooling water pump.

Fill the system with coolant via the reservoir until the proper level is achieved. It may be necessary to remove a bleeder screw on the reservoir when initially filling the cooling system on some reservoirs. Install the cap and bleeder screw if present, on the reservoir. Turn on the ignition (do not start car), set the heat to maximum and the blower on the lowest setting. Begin by pressing the accelerator pedal to the floor for at least 10 seconds; be sure NOT to start the engine. Release the accelerator pedal and within a moment, the pump can be heard during activation. While the bleed procedure is being performed, inspect for leaks. The procedure can be repeated several times as needed, turning the ignition off for 5 minutes between each bleed procedure.

[Legokcen]

Thanks a lot! I appreciate it!

Originally Posted by smassey321

Pressurized overflow tanks are a European car thing. Once the new tank is in place, you may want to bleed the air from the system.

This bleed procedure works on all vehicles with the N52, N51, N52K and N54 engine, operating with electric cooling water pump.

Fill the system with coolant via the reservoir until the proper level is achieved. It may be necessary to remove a bleeder screw on the reservoir when initially filling the cooling system on some reservoirs. Install the cap and bleeder screw if present, on the reservoir. Turn on the ignition (do not start car), set the heat to maximum and the blower on the lowest setting. Begin by pressing the accelerator pedal to the floor for at least 10 seconds; be sure NOT to start the engine. Release the accelerator pedal and within a moment, the pump can be heard during activation. While the bleed procedure is being performed, inspect for leaks. The procedure can be repeated several times as needed, turning the ignition off for 5 minutes between each bleed procedure.

[Toothbrush]

Also, be prepared to replace hoses elsewhere if it's never been done on that vehicle.

You may want to get a small mirror and check the underside of all the hose fittings you can get to. Check for dried white spots (antifreeze) and/or brownish discoloration.

Edit: just noticed it looks like your engine partition is broken. You might want to fix that as well. It's fairly easy to do. Helps keep liquids off the engine in places it shouldn't be.

See here: https://xoutpost.com/bmw-sav-forums/...partition.html

[SF2000x5]

From personal experience with a few Bmws in my circle, these reservoirs seem to need replacing every 10 years to prevent failures.

They can either start showing small signs of seepage or explode. Seen reservoirs fail on an e36, e39, e70, e90. The older two don’t have seams to leak so they exploded.

[Legokcen]

Thanks again for all the help. I changed the tank in about 20 minutes and the priming sequence was spot on. This is a great resource of information. I really appreciate all the help. I'll look at the engine partition also, thanks for the suggestion.

With the vehicle being 12 years old and the with so few miles (56K), I'm hoping it'll last me for a few years. My parents didn't drive it much the last couple of years (~2K year) so I just want to be confident that it'll continue to be reliable.

Anything else I should check anywhere or proactively look at? I can pretty much do most things myself.

One more question, the Y plastic hose piece was brittle and broke while I was replacing the tank. I had to use a hose clamp with whatever was left to hold on to. Isn't permanent, but it got me home and I want to replace it. Is BMW the best place to get one of these or can I order online. I stopped by an Autozone and got some fitting that were mainly vacuum line fittings that would fit it, but I'm not sure a vacuum line fitting will handle the heat/pressure of the coolant system. Thoughts? Picture is below:

[SF2000x5]

I would just replace the whole assembly including hoses from fcp with a lifetime warranty: https://www.fcpeuro.com/products/bmw...x5-11537547244

[Legokcen]

Originally Posted by SF2000x5

I would just replace the whole assembly including hoses from fcp with a lifetime warranty: https://www.fcpeuro.com/products/bmw...x5-11537547244

Awesome! Ordered. Thank you!