[sebastian_tyg]

I have a 2006 330xi with about 89xxx miles. I did a coolant system flush on Monday and installed two new radiator drain plugs. I came home last night parked in my driveway and out of curiosity I checked under the car and saw a small coolant leak. Dripping from the back of the splash shield under the car. Let the car sit overnight and checked coolant level this morning and it was on minimum so I added a little bit more till it reached max.

What's the possibilities of this leak? I checked the hoses and they look in good conditon. When I get home tonight I will go under the car take the splash shield off and check for any leaks. Any recommendations on what I can possibly be looking for or at?

Thanks in advance!

[sebastian_tyg]

Bumppppp

[PichaDis11]

You'll be looking at possible leaks in all corners of the cooling system. check hoses (Give em a lil squeeze), reservoir. make sure you tightened you hose clamps and so forth.

You might not have a leak either. Did you perform the bleed procedure after the flush?

[Efthreeoh]

I've been through the entire E90 (N52) cooling system, so I know it pretty well. I've replaced the entire 9-hose hose set (included the heater core hoses) along with the t-stat and water pump (all at different times ).

If the only thing you opened up in the cooling system to do the flush was the two drain plugs in the radiator, then start there. I hope you did not attempt to open the plugs using the white nut, and only unscrewed the blue drain screw. Using the white nut will break the drain valve. If you over-torqued the blue drain screw(s) going back in you could have cracked one and it is leaking. Generally if you didn't remove any hoses then you shouldn't be leaking anywhere. If you pulled off the u-shaped hose, then check that to see if it seated correcly. if you messed with the temperature sensor located in the lower hose connector body, it is probably leaking. Once the sensor is set in place, it is really not remove and replaceable and a new fresh sensor is needed if you've ever removed it.

Good luck.

Did you replace the radiator too? Why did you replace the hoses? Preventive?
Did any particularly look worn? When I did my water pump/tstat at 130k miles all the hoses showed no wear.

[Efthreeoh]

Originally Posted by index1489

Did you replace the radiator too? Why did you replace the hoses? Preventive?
Did any particularly look worn? When I did my water pump/tstat at 130k miles all the hoses showed no wear.

I published a DIY about it in January. I replaced all the the hoses as preventative maintenance at around 230,000 miles and 7.5 years old. All the hoses were still in good shape. I did not replace the radiator.

[sebastian_tyg]

Originally Posted by Efthreeoh

I've been through the entire E90 (N52) cooling system, so I know it pretty well. I've replaced the entire 9-hose hose set (included the heater core hoses) along with the t-stat and water pump (all at different times ).

If the only thing you opened up in the cooling system to do the flush was the two drain plugs in the radiator, then start there. I hope you did not attempt to open the plugs using the white nut, and only unscrewed the blue drain screw. Using the white nut will break the drain valve. If you over-torqued the blue drain screw(s) going back in you could have cracked one and it is leaking. Generally if you didn't remove any hoses then you shouldn't be leaking anywhere. If you pulled off the u-shaped hose, then check that to see if it seated correcly. if you messed with the temperature sensor located in the lower hose connector body, it is probably leaking. Once the sensor is set in place, it is really not remove and replaceable and a new fresh sensor is needed if you've ever removed it.

Good luck.

So I finally ran a pressure test and coolant was leaking through the back of the expansion tanks which is cracked...

Anyone knows how much an expansion tank is going to run me? And should I replace the radiator hoses as well?

[Efthreeoh]

Are you speaking of the coolant reservoir (it's not a traditional "expansion" tank)? Or are you actually talking about the radiator side tanks? It seems quite odd that the reservoir would crack. Mine is fine after 250K miles and one overheating event when the WP died at 150K. Hoses are really your call and how comfortable you feel about their reliability. Mine all looked to be in good shape when I replaced them in December at around at 235K. Hoses deteriorate with age AND mileage, so it's hard to say replace at a certain mileage, but age is the more important factor and generally 10 years is considered max life for hoses in modern automobiles. My thought is, if you are going to replace a few because or reliability concerns, then replace them all. The complete hose set is around $450 - $500. Get a new temperature sensor with the new hoses; the temp sensor is a one-time use item.

Good luck

[sebastian_tyg]

Originally Posted by Efthreeoh

Are you speaking of the coolant reservoir (it's not a traditional "expansion" tank)? Or are you actually talking about the radiator side tanks? It seems quite odd that the reservoir would crack. Mine is fine after 250K miles and one overheating event when the WP died at 150K. Hoses are really your call and how comfortable you feel about their reliability. Mine all looked to be in good shape when I replaced them in December at around at 235K. Hoses deteriorate with age AND mileage, so it's hard to say replace at a certain mileage, but age is the more important factor and generally 10 years is considered max life for hoses in modern automobiles. My thought is, if you are going to replace a few because or reliability concerns, then replace them all. The complete hose set is around $450 - $500. Get a new temperature sensor with the new hoses; the temp sensor is a one-time use item.

Good luck

Yes the coolant reservoir is what I'm talking about...what's the difference between that and expansion tank then? I have 91xxxmi on the car, my hoses aren't cracked or anything but I hear a lot of people changing their hoses when they have any type of coolant leaks...I just don't want it to be a problem near the future. If that's the real price for the complete hose set then I might just leave it as is (getting rid of the car next summer). And I was in a car accident in March where I was hit on passenger side so I guess that's where the crack came from. I tried calling the body shop to blame them for my overheating problem since they obviously didn't replace the coolant reservoir but they keep claiming that it was in good shape and didn't need replacement...fighting with body shops and insurance companies can be stressing and irritating

A new tank is like ~$60. Replace that and be done with it.

For the hoses, if they ain't broke then don't fix 'em.

[XM_Rocks]

Hate to thread jack but I am flushing coolant tomorrow.

However I will be driving 15 miles to the place where I am renting a lift.

Any advice on dealing with a hot coolant and the pressures?

Rag over the cap when opening?

Letting the coolant cool for 30 mins?

[MacR6]

Originally Posted by FCobra94

A new tank is like ~$60. Replace that and be done with it.

For the hoses, if they ain't broke then don't fix 'em.

+1


Did this with the T-Stat and water pump.

[Efthreeoh]

Originally Posted by sebastian_tyg

Yes the coolant reservoir is what I'm talking about...what's the difference between that and expansion tank then? I have 91xxxmi on the car, my hoses aren't cracked or anything but I hear a lot of people changing their hoses when they have any type of coolant leaks...I just don't want it to be a problem near the future. If that's the real price for the complete hose set then I might just leave it as is (getting rid of the car next summer). And I was in a car accident in March where I was hit on passenger side so I guess that's where the crack came from. I tried calling the body shop to blame them for my overheating problem since they obviously didn't replace the coolant reservoir but they keep claiming that it was in good shape and didn't need replacement...fighting with body shops and insurance companies can be stressing and irritating

This would have been nice information for us to know up front to help you diagnose the issue. It totally transforms the question. Now rather than questioning the age and longevity of the other parts of the cooling system, the issue merely exists because of a mechanical problem due to a forcing function called a "car accident".




The difference between an expansion tank and coolant reservoir is that in some cooling system designs the radiator holds all the coolant and the expansion tank (that goes with this type of design) provides a container for the expansion and contraction of coolant, which allows for the system to keep coolant in reserve as it slowly escapes as vapor over time. Expansion tanks are not pressurized. The E90 cooling system design uses a coolant reservoir that holds part of the coolant load (rather than the radiator) and is an active part of the cooling system. The E90 coolant reservoir IS pressurized. This is an important distinction because expansion tanks can be safely opened (to add coolant) when the cooling system is hot and under pressure. The reservoir-type design BMW uses cannot be safely opened while hot; if it is opened while hot it will scald the person opening it. The key to understanding which design the car uses is the location of the pressurized "radiator cap". If the radiator cap is on the radiator, then the system is an expansion tank design. If the radiator cap is on a tank separate from the radiator (as on the E90) then it is a reservoir tank design. Expansion tanks are usually opaque/white (HDPE plastic) and have a snap-close cap (that doesn't hold pressure).

As far as the repair, most insurance companies allow for a 2-year period of subsequent repair due to problems found after the initial repair is completed. This seems like a classic case where the coolant reservoir was compromised as a result of the accident, but the symptoms didn't show up until later. Obviously the tank was stressed during the collision and was cracked. Over time, with heat and pressure, the crack turned into a leak. A simple and congenial investigation into the situation with the body shop with understanding that you would contact the insurance company for an addendum repair against the original repair order (i.e. no additional deductible for you or the paying insurance company). Approaching the body shop as the problem with the tank was not detectable at the time of the estimate and repair, rather than accusing them of fucking up, probably would have gotten you a bit farther with getting the tank replaced as part of the original repair order.