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07 X3 3.0si Coolant Leak *FIXED*

40K views 22 replies 7 participants last post by  cagui1223 
#1 · (Edited)
Mileage: ~103,000
Over the past few months the "low coolant" light has turned on, which never happened before. I'd top it off and after a month it would turn back on. Off I went hunting down the leak... Found it!
It appears it may be leaking from:
  1. Area where the expansion tank sits on the mounting plate
  2. Water pipe connector.
  3. Level sensor
  4. Overflow hose?
Pictures below the vehicle:
Auto part Automotive lighting Engine Fuel line Vehicle


Auto part Vehicle Car Bumper Automotive lighting


This one was taken from the side.
Auto part Tire Automotive wheel system Automotive tire Engine


Based on the last picture, this hose goes from the water pipe connector all the way to the thermostat. Should I replacing this hose? Is this the overflow hose?
The diagram from RealOEM.com says the part # is 17123422785. When I plug this into certain sites it says its not compatible with my vehicle...

Parts Ordered:
www.ECSTuning.com
Coolant Expansion Tank
Mfg Part# 17117573781
ECS Part# ES#2091434

Water Pipe Connector
Mfg Part# 17112248409
ECS Part# ES#38012

------------------------------

www.Bavauto.com
Expansion Tank Thermostat
Part # 17 11 1 437362A

Upper Radiator Hose
Part # CHR0186P

Lower Radiator Hose
Part #CHR0187P

Expansion Tank Retaining Clip
Part # 17 13 2 248 252

Fluid Level Sensor
Part # 52041

Didn't order any coolant since I already have some.
 
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#2 · (Edited)
Hello everyone,
I hadn't updated this since several parts were on back-order. I finally received all the parts and got to work on it this weekend. The job was fairly simple and completed within a matter of about 3 hours. In all I spent about $200.00 on parts.

** I am not a mechanic, just enjoy fixing my own cars and saving money. Proceed at your own risk **

Make sure the engine and its components are cold before you work on this!

Step 1: Begin to drain the coolant. I decided to drain from the water pipe connector (Doesn't matter which one you decide to drain from IMO). It's easy to find the drain plugs since they're BLUE underneath the vehicle, drivers side front (FIG. 1). Be sure to remove the cap off the radiator to allow more fluid out. A little over a gallon of coolant came out.
FIG. 1
Product Auto part Automotive lighting Engine Automotive tire


Step 2: As the coolant drained I began removing the Air Duct (FIG. 2) and Intake Duct (FIG. 3). These are held down by Torx screws, can't recall the size.
FIG. 2
Land vehicle Vehicle Car Automotive exterior Bumper


FIG. 3
Vehicle Car Engine Auto part Luxury vehicle


For the Air Filter Housing Unit, push the spring clips off, disconnect the MAF(Mass Air Flow) connector and release the clamp holding the Air Filter to the rubber boot (FIG. 4).
FIG. 4
Auto part Vehicle Car Engine City car


Remove the air filter and now you'll just have the bottom half of the Air Filter Housing unit left. This piece you just need to lightly pull out of the vehicle as there are no screws holding it down.
FIG. 5
Auto part Engine Vehicle Car Carburetor


Once all these parts have been removed, this is what you're left with (FIG. 6)
FIG. 6
Auto part Engine Vehicle Car Automotive engine part


Here are a few things labeled (FIG. 7)
FIG. 7
Green: Expansion Tank
Red: Upper Radiator Hose
Yellow: This is where the Air Filter Housing sits.
Vehicle Auto part Engine Car Automotive engine part


Step 3: Remove Upper radiator hose. This hose has 4 different points of entry. Each one has a retaining clip which need to be partially pulled out to remove the hose. Use a flat-head screwdriver or a thin knife for greater ease. Please note the hose will only go in 1-way so "twisting" the hose when pulling doesn't really help. Refer to FIG. 8
FIG. 8
Auto part Vehicle Engine Car City car


Remove this hose as well (FIG. 9). I'm not sure exactly what this hose is.
FIG. 9
Auto part Engine Vehicle Car Automotive engine part


Step 4: Remove the Expansion tank. Now that the hoses have been disconnected, there is only 1 retaining clip holding it onto the radiator mounting bracket. The clip is located directly underneath the expansion tank. It can be reached from above the expansion tank, next to the radiator fan. Refer to FIG. 10.
Pull the expansion tank upwards, just be careful when doing so since the coolant level sensor is also connected below, don't stretch the wire!
RED: Retaining Clip
GREEN: Coolant level sensor
FIG. 10
Auto part Tire Automotive wheel system Automotive tire Fuel line


Here's what it looks like once expansion tank has been removed (FIG. 11).
FIG. 11
Auto part Fuel line Engine Suspension Vehicle

Blue Arrow: This is the water-pipe connector. Because of the way it was designed the only way it'll come out is by bringing the whole radiator out. I ultimately decided not to change this piece since it wasn't leaking AND I couldn't remove the radiator fan... :(

RED Arrow: Inside this large hole goes the transmission thermostat. I would highly recommend replacing this piece. Overtime it became brittle and broke easily when I tried removing it. Since it was in pieces I had to use a flat-head screwdriver to pull the remaining pieces out. When placing the new thermostat, use a bit of downward force until the piece "sinks" into place.
Transmission Thermostat Picture
Lens Camera lens Optical instrument Monocular


Step 5: Replace Expansion tank. Insert the new coolant level sensor into the bottom of the expansion tank and work in reverse.

TIPS:
When replacing expansion tank, DO NOT forget to reconnect coolant sensor. Make sure the expansion tank fits snug against the mounting bracket and DO NOT forget to reconnect the retaining clip. Make sure the water-pipe connector is also snug in place, so try to push this piece further in from the bottom.
Each hose needs to be properly seated. Once done so push the retaining clip in place and try pulling on the hose to see if it releases easy. If so, then its not securely in place. Fill with BMW coolant until the "full" point and be sure to use the bleeder screw to burp the system. Check for leaks, all should be well, sit back and enjoy the savings!
 
#3 ·
Nice write-up.
I replaced my expansion tank about 2 weeks ago. Didn't have a heater hose seated properly with the clip & ended up losing about a gallon when the hose blew off on the road. Good way to fry a head if you're not careful. Never played with the connector/clip mechanism on hoses before so I wasn't paying attention.
My advice to everyone is not to overfill the expansion tank. IMO, these things start leaking because of too much pressure that isn't efficiently released by the pressure relief valve built into the cap. You need to actually siphon some out after the initial filling to get a good reading on the indicator stick. Filling these plastic tanks to the top as you would a typical radiator is a no no...
 
#4 ·
+1.
I filled it up to the point where the bleeder screw started pouring fluid out. I put the cap back on the expansion tank then opened up the bleeder screw once again and let some fluid pour out to make sure it was not low on fluid or had anymore air trapped inside.
 
#5 ·
I guess I'm paranoid about too much pressure on these plastic tanks...
Once I had it filled and the air bled out, I suctioned enough out of the tank so the indicator stick wasn't floating at its maximum. The car has got to go thru 2 or 3 heat/cool cycles before the coolant level settles down. Check it each time (cold of course) during each cycle and you'll probably need to add a little coolant. On mine, I'm not letting the stick rise to its maximum... rather, once it starts floating I don't let it max out, but allow it to float between the marks. That way I'm sure its not overfilled or underfilled....
Haven't had a single drop since the repair.
 
#7 ·
..... On mine, I'm not letting the stick rise to its maximum... rather, once it starts floating I don't let it max out, but allow it to float between the marks. That way I'm sure its not overfilled or underfilled....
+1

A lot of people interpret "Max." as meaning "fill to here".

May not be a big deal with engine oil level, brake fluid level, etc., but with the coolant level in these BMW's there does seem to be evidence that there is not much margin for error.

Depending on cold or warm coolant, and the fact that it is difficult to sight along the top of the expansion tank and judge if the float max. mark is aligned where it should be,
aiming for the safe middle ground is the best plan.
 
#10 ·
Expansion tank does not want to come out...

Hello,

I have all top hoses disconnected and the clip from the bottom loose, however the expansion tank does not want to come out no matter how many times I have pulled upwards:mad:. Any suggestions?
 
#18 ·
Hi,

Yes, right after I posted the message, I gave it another copuple of tries and it came out but I broke the thermostat for the transmission. I am kind of grad that it broke because it forced me to removed it and then I realized that bottom part was so brittle that was it was breaking a part. The bad part is that I didn't have a spare one for the X3 and it didn't look like I was going to get one until the end of the week even from the dealer. So, I took apart the broken one and a new one that I had for a e46, I figured out the body of the thermostat is the same for both of them, so I put the inside parts of the old one in the body of the new one. That saved the day and everything seems to be running fine.

BTW... Thanks everybody for the replies and suggestions.
 
#19 ·
Hi,

Yes, right after I posted the message, I gave it another copuple of tries and it came out but I broke the thermostat for the transmission. I am kind of grad that it broke because it forced me to removed it and then I realized that bottom part was so brittle that was it was breaking a part. The bad part is that I didn't have a spare one for the X3 and it didn't look like I was going to get one until the end of the week even from the dealer. So, I took apart the broken one and a new one that I had for a e46, I figured out the body of the thermostat is the same for both of them, so I put the inside parts of the old one in the body of the new one. That saved the day and everything seems to be running fine.

BTW... Thanks everybody for the replies and suggestions.
Thanks for getting back to us!!

I'm glad you were finally able to remove the expansion tank! It sucks the thermostat broke, however, it's a good thing it happened while you could see it rather than once everything was put back together and have to diagnose another problem. Very creative swap to get a working thermostat!

Sent from BimmerApp mobile app
 
#17 ·
I agree that rotating the expansion tank too much when trying to bring it out might make contact with the thermostat therefore breaking it. However, bear in mind the thermostat is fully submerged in coolant and exposed to rapid and constant change in temperature. The plastic it's made of becomes brittle overtime.
My thermostat was intact when I removed the expansion tank. The top cap broke with pressure I applied using my fingers when trying to pull it out.
 
#21 ·
Read some of the other threads on the N52 engine. The bleeding procedures for this engine are different. Consider replacing the water pump and thermostat too, but they are not cheap on these cars. 100k replacement is practiced for those running on PReventaive maintenance strategy.
 
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