[digital01]

So the other day, my 06 325i displayed dumny lights on the dash for overheating. I checked the reservoir tank and there was almost mo fluid left. Knowing that there must be a leak sonewhere, I decided to try driving it home slowly (about 5-10 miles) after topping off the coolant. About 2-3 miles down the road, the yellow overheat message popped up again, followed by the red one. Right before i had a chance to pull over, i heard a popping noise and saw excessive amounts of fluid behind me. I pulled over and noticed that the plastic fitting on the drivers side of the radiator had cracked completely. I figured that this was the culprit of the leak, and went ahead and got the car towed home, then purchased/installed a new radiator. After install, I bled the system of air (which people compare the noise to a washing machine, but i didnt hear anything) and attempted to crank the motor. Took it on a test drive, but immediately noticed that the fan was spinning excessively. Furthermore, the heater was still blowing cold air. Sure enough, the dummy lights cane on again!

And this is where im stuck. Im leaning towards the water pump/thermostat, however id like to be sure prior to purchasing since its 400+ just for the pump. Ive heard of e90s being prone to water pump failure at around 70k, and my car is currently at 55k. Seems a bit premature for the pump to fail, but im sure its possible.

Does anyone have any insight on this issue? Ive been pulling my hair out for the past 3-4 days trying to figure this out. Such a headache. Any help would be much appreciated!

[GoRomeo]

You should read codes next. You have a new radiator which is good, you needed one after the crack. Now, next step is to read codes and go after WP, thermostat. These pumps can go at anytime, Your radiator crack could be caused by a stuck closed thermostat or overheating.

Ive seen WP prices for your car around 300 ish and thermostat for about 80. Good luck and keep us posted.

[///M3NACE]

Once you overheat your car to high temp the weakest part of the cooling system blows and in this case hour radiator. I would check codes and if it is thermostat I would do water pump at the same time depending how many miles you have on it.

[SDemetris]

Mine went at 45 or 50k so not unheard of.. I would check where the leak is and replace that and the waterpump together

[digital01]

Thanks for the quick replies! Regarding codes, is this something that i can diagnose using the dash diagnostics, or will I need an ODB plug-in unit?

Also, what specific symptoms would a broken thermostat cause as opposed to a faulty water pump? I do remember initially seeing radiator fluid that leaked out somehow on the passenger side, so much that it was all over the front passenger side wheel. This was prior to the radiator giving out. If i remember correctly, the pump/thermostat is located in the general vicinity of the initial "leak".

[digital01]

The weird thing is that after changing the radiator, the leak on the pass. side is gone. Is it possible for a stuck thermostat to cause leaking due to pressure buildup?

[GoRomeo]

Of course, overheating causes more pressure. Its rare when these thermostats get stuck closed. Mine I believe is stuck open since it gave error code last year. Mine on the contrary runs colder than it supposed to since coolant is always flowing.

It could be that your themostat is partially closed thats why is creating more preasure in the coolant system. Try not to run you car if its overheating you could cause more real damage to the engine.

[///M3NACE]

Honestly just go to the dealer and let them diagnose it for you. Do the repair yourself or an Indy. Or just take it to a trusted Indy for diagnostic. You don't wanna blow your headgasket on these cars.

[GoRomeo]

IT could also be your tempeture sensor that is bad and not turning fan when it supposed to. To confirm this read codes first.

[digital01]

Originally Posted by GoRomeo

Of course, overheating causes more pressure. Its rare when these thermostats get stuck closed. Mine I believe is stuck open since it gave error code last year. Mine on the contrary runs colder than it supposed to since coolant is always flowing.

It could be that your themostat is partially closed thats why is creating more preasure in the coolant system. Try not to run you car if its overheating you could cause more real damage to the engine.

Yes, I have heard of engines running cooler when stuck open like that, however I havent heard of much regarding the thermostat staying closed. I guess i should start snooping around that area. Thanks for the input

[NorthernCAE90]

damn this scares the shit out of me. Bought my 325 6months ago (now at 54k) and I really don't see how a car with less than 60k can blow a radiator that's just insane. but everyone on here replies "oh that's how bmw works"...... And as the same as you ive read also that the waterpump tends to fail around 70k and that the fan spins freely when waterpump is out.

[bmrman1]

Run bleeding procedure and check water pump activation. You should be able to see water flowing in your expansion tank. If you don't see this check for proper voltage and ground to water pump. If it is ok your water pump failed. By your description it is most likely you have a bad water pump.

[balbains324]

I'm redirecting an old thread here but I have an overheating issue with my 318d e90. Same procedure with amber light and limp mode, but the water pump is running because I changed thermostat and expansion tank shows water flowing. No leaks anywhere. I want to know where the coolant temp sensor is located because it is reading 130 degrees centigrade but the water is not hot it is barely warm in the expansion tank.
I think I will try and replace temp sensor before I go for the pump. Just need to know where it is if anyone can help it would be appreciated.

[RazRokz.!]

Ecs tuning has off brand water pumps for our cars. If you have to replace your pump, check them out. It'll save you some money...

[Volasko]

You tried the air bleeding procedure and didn't hear anything, your water pump is cooked!

[TheSt|G]

Originally Posted by GoRomeo

Of course, overheating causes more pressure. Its rare when these thermostats get stuck closed. Mine I believe is stuck open since it gave error code last year. Mine on the contrary runs colder than it supposed to since coolant is always flowing.

It could be that your themostat is partially closed thats why is creating more preasure in the coolant system. Try not to run you car if its overheating you could cause more real damage to the engine.

BMW thermostats by design fail open, as clearly it is much better to run cool rather than overheat.