[jg28xi]

I was driving my e92 328xi 2008 right after I had just got a new radiator and cats installed at the dealer.

After leaving the dealer not even 5 miles and less than an hour after I got the car I got the yellow indicator that my engine was too hot and then the red indicator that I was overheating. My car had stopped but I was stuck in the intersection so I turned on my car to pull it out of the intersection really quick but I heard a big pop on the right side of my hood.

I immediately turned it off and got out of the car and to my discovery there was coolant on all sides underneath my car.

I quickly towed it back. the dealer called back today and let me know that it was the expansion tank that was blown... and that it happens due to the age of my car? They are going to charge me for the part and not for labor for the inconvenience. Should I be worried about any engine damage? is possible for my headgasket to blow from that? Will they be shady and not tell me?

[Tambohamilton]

I would not be happy about that. The car was overheating *before* the expansion tank gave up, so the problem was caused by something they did. I suspect the expansion tank only popped because the engine was overheating... Presumably they didn't refill or purge the coolant system properly.

[Efthreeoh]

The engine is fine. Many E9X's overheat when the water pump dies. A brief overheat doesn't hurt the N52. Mine overheated in 2011 at 149,500 miles when the pump went tits up. Been fine ever since with now well over double the miles.

[CTinline-six]

I doubt you blew the head gasket. These cars go into limp mode before any engine damage is done. IMO this is a design improvement over the E46 where it will overheat the engine if you aren't watching the gauge at the exact moment the expansion tank blows out all the coolant.

[DiFFv1]

Originally Posted by Tambohamilton

I would not be happy about that. The car was overheating *before* the expansion tank gave up, so the problem was caused by something they did. I suspect the expansion tank only popped because the engine was overheating... Presumably they didn't refill or purge the coolant system properly.

+1

So they are replacing the expansion tank, What about the water pump? I would definitely make sure they purge the system and then monitor your temps afterwards for possible water pump failure. This could be a simple mistake but nothing is wrong with covering all angles as well.

[CTinline-six]

What is the mileage in/out on your receipt? Did they even test drive the thing or just slap it back together and shipped it?

[jg28xi]

Originally Posted by Tambohamilton

I would not be happy about that. The car was overheating *before* the expansion tank gave up, so the problem was caused by something they did. I suspect the expansion tank only popped because the engine was overheating... Presumably they didn't refill or purge the coolant system properly.

I had to pay for my own tow.. everything before was done under warranty. They only test drive the vehicle 2 miles. Is there any way to complain? I'm a younger driver so I feel like they are trying to take advantage of me. I went in with a used BMW to get a sulev warranty. I feel like they rushed my job and are trying to cover up there mistakes.

[jg28xi]

Originally Posted by CTinline-six

What is the mileage in/out on your receipt? Did they even test drive the thing or just slap it back together and shipped it?

They only test drove it for 2 miles.. went in at 107716 and out at 107718..

[jg28xi]

Originally Posted by DiFFv1

+1

So they are replacing the expansion tank, What about the water pump? I would definitely make sure they purge the system and then monitor your temps afterwards for possible water pump failure. This could be a simple mistake but nothing is wrong with covering all angles as well.

I'm going in to pick it up today... I was supposed to get it last night but I asked for extra quality check so they're gonna do extra test drives for me? I'm new to going to the dealer and not a car guy. That's why I'm seeking a 3rd opinion on the forum.. idk how to deal with this

[jg28xi]

Originally Posted by CTinline-six

I doubt you blew the head gasket. These cars go into limp mode before any engine damage is done. IMO this is a design improvement over the E46 where it will overheat the engine if you aren't watching the gauge at the exact moment the expansion tank blows out all the coolant.

Thank you for the information

[Efthreeoh]

Why was the radiator replaced? And I agree, you need to ask them if they checked for water pump trouble codes. It could be the water pump coincidentally failed after the repair to the radiator, which caused the engine to overheat.

[Efthreeoh]

Originally Posted by DiFFv1

+1

So they are replacing the expansion tank, What about the water pump? I would definitely make sure they purge the system and then monitor your temps afterwards for possible water pump failure. This could be a simple mistake but nothing is wrong with covering all angles as well.

The N52 runs four(4) different coolant temp profiles. Observing the coolant temps is not a good indicator of pump health. Scanning for WP trouble code is a good way to determine WP health.

[jg28xi]

Originally Posted by Efthreeoh

Why was the radiator replaced? And I agree, you need to ask them if they checked for water pump trouble codes. It could be the water pump coincidentally failed after the repair to the radiator, which caused the engine to overheat.

When they did a pressure test at 20 psi apparently there was coolant leaking from radiator. So they replaced it under my sulev warranty.

[Efthreeoh]

Originally Posted by jg28xi

When they did a pressure test at 20 psi apparently there was coolant leaking from radiator. So they replaced it under my sulev warranty.

Okay, but why did they pressure test the cooling system? Did you complain about something, like loss of coolant. A dealer just doesn't go and pressure test a cooling system without provocation.

[mdonley08]

I had the expansion tank explode yesterday 08 335i, came across this thread. Only difference is last week I replaced the lower hose that runs from under the oil filter housing to thermostat because it broke off at the engine connector (brittle plastic) I refilled with BMW antifreeze but didn’t bleed the system after filling, forward to yesterday the expansion blew open with a 6” crack on the outside. My question is, did the hose blow off and expansion tank explode because of water pump or thermostat failure. Car never ran hot... I’ve ordered the tank, and will bleed the system correctly when it arrives. Car has 228k miles and has been one of the best cars I’ve ever owned until about 2 months ago. Seems like one thing after the other.. I’ve tried to use the “if it isn’t broke don’t fix it”...

[Efthreeoh]

Originally Posted by mdonley08

I had the expansion tank explode yesterday 08 335i, came across this thread. Only difference is last week I replaced the lower hose that runs from under the oil filter housing to thermostat because it broke off at the engine connector (brittle plastic) I refilled with BMW antifreeze but didn’t bleed the system after filling, forward to yesterday the expansion blew open with a 6” crack on the outside. My question is, did the hose blow off and expansion tank explode because of water pump or thermostat failure. Car never ran hot... I’ve ordered the tank, and will bleed the system correctly when it arrives. Car has 228k miles and has been one of the best cars I’ve ever owned until about 2 months ago. Seems like one thing after the other.. I’ve tried to use the “if it isn’t broke don’t fix it”...

Why wouldn't you bleed the system? It takes 15 minutes, 12 to run the pump, and 3 to top off the coolant level and check for leaks.

[mdonley08]

Originally Posted by Efthreeoh

Why wouldn't you bleed the system? It takes 15 minutes, 12 to run the pump, and 3 to top off the coolant level and check for leaks.

Honestly I wasn’t aware the system needed bleeding until I read more on replacing expansion tank. I’m used to just running the vehicle and letting the bubbles come out from the radiator cap... I know, stupid mistake. Now I’m worried the water pump is bad and I’m gonna add this coolant to just drain it after testing.. anyway to test the water pump without running it??

[Efthreeoh]

Originally Posted by mdonley08

Honestly I wasn’t aware the system needed bleeding until I read more on replacing expansion tank. I’m used to just running the vehicle and letting the bubbles come out from the radiator cap... I know, stupid mistake. Now I’m worried the water pump is bad and I’m gonna add this coolant to just drain it after testing.. anyway to test the water pump without running it??

Just scan the car with a BMW scan tool. There are manaufacturer-specific (i.e. BMW) trouble codes if the water pump is having problems. The DIY subforum on E90 Post will help you with almost any repair you need to do. There are tons of BMW technical information on the web, so there is no need to hack on your car. Research and do it right, it saves on headaches.

[mdonley08]

Thank you very much, I agree 110% that hacking away doesn’t end well. I’ve basically used this forum to replace/repair almost everything I’ve done. Thanks to all who’ve supplied the great diy info. I’m currently uploading the usb obd2 interface and mikes tools. Hopefully I can run this down and make my life easier, I enjoy bragging about this car having 228k miles and running strong. Thanks again!