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-   -   New OEM Coolant Expansion tank leaking? Could it be?! [UPDATE - Not fixed (UGH)] (http://www.bimmerfest.com/forums/showthread.php?t=669536)

awdrev 01-11-2013 09:39 PM

New OEM Coolant Expansion tank leaking? Could it be?! [UPDATE - Not fixed (UGH)]
 
So one of the first things I did when I got my 04 X3 is to replace the coolant expansion tank because the car was leaking coolant.

Well, it turns out that the leak was actually coming from the TOP RADIATOR hose (which I obv replaced) so, technically speaking, I didn't have to replace the coolant tank but I am glad that I did given that it had over 8 years of use. From what I can gather, the tank has been there since 2004.

Now, when I topped off the expansion tank, I noticed that it continued to leak. I left it alone because the car was hot and I didn't want to deal with it since it was a good amount...

Then I kept checking and the amount leaked has significantly reduced but it continues to do so.

Here's the situation: From what I can see, it seems there a small residue of engine coolant RIGHT AT THE TOP OF THE TANK... I am starting to believe that either this new tank is defective, or it could be the hose connection to the radiator that is leaking... just as a reference, this IS the top radiator hose that connects to both the coolant tank AND the radiator

As I said, the coolant tank was purchased from a BMW dealer... any thoughts or past experiences?

Thanks again

bmwbob89 01-12-2013 03:10 AM

Make sure the smaller hose at the top of the tank is fully seated. It is rather difficult to get it completely snapped in. Look at another one and make sure yours is seated.

mlukas161 01-12-2013 06:02 AM

Did you replace the expansion tank cap with a new one or reuse the old one?

awdrev 01-12-2013 06:39 AM

Thanks Bob.

Mlukas, I used the old one... could that be it? I mean, it is a VERY SMALL leak and I think it only happens when the car is hot so when the fluid fully expands... I thought it would be the cap too. I didn't see a leak around the neck though, it's mostly around the edges, and it's very little... enough to see the color stain but at times it's bigger

mlukas161 01-12-2013 07:44 AM

I've always heard it should be replaced with a new one. If its a really small leak I would try that first. Especially bc its an easy an inexpensive fix. Might be worth a try.

awdrev 01-12-2013 08:11 AM

Just bought it, it will be VERY interesting if that's the source. I will update when it arrives next week.

x3brian 01-12-2013 08:50 AM

Aw--that would be my suspicion too. Keep us updated.

mlukas161 01-12-2013 02:43 PM

Cool. Yeah, let us know what happens.

silentbob 01-12-2013 07:42 PM

Quote:

Originally Posted by bmwbob89 (Post 7307708)
Make sure the smaller hose at the top of the tank is fully seated. It is rather difficult to get it completely snapped in. Look at another one and make sure yours is seated.

+1. There is also a little notch to key the big hose at the top. Make sure the big hose is completely pushed in, so that it completely covers the notch. The little ring clip should be VERY tight. If it feels loose, you've probably not pushed in the hose far enough.

Supercourse 01-13-2013 09:14 AM

Quote:

Originally Posted by awdrev (Post 7307473)
....... when I topped off the expansion tank, I noticed that it continued to leak. I left it alone because the car was hot ......... I kept checking and the amount leaked has significantly reduced but it continues to do so.

I don't think it's necessary in general to have a new cap when replacing an expansion tank.

The rubber seal does dry out but as long as it isn't damaged through over-tightening it can be made flexible again by applying a bit of coolant to it with your finger.

Same with the plastic threads, to make the cap easier to screw on and off.

The plastic cap on an expansion tank looks to me as though it is quite different than the old metal type directly on the radiator which did need replacing routinely.

Not saying it applies here, but it's worth noting that it only takes a cupful or less of coolant mix to bring the float from below the neck up to the Max. position.

Pouring more in doesn't make the float go any higher above Max. but it does mean that it will want to vent out once the car is running.

suss1173 01-18-2013 10:29 AM

Anyone know how long BMW (or any fair indy shop) quotes to replace the water pump, T-sat, and expansion tank on an E 83 (2006-X3-3.0)

Not looking for the price of parts, just the amount of time/ labor.
Thanks

awdrev 01-18-2013 12:55 PM

Quote:

Originally Posted by mlukas161 (Post 7307803)
Did you replace the expansion tank cap with a new one or reuse the old one?

Update: I think the leak was because of excessive coolant. I got the new cap and I took the old one out.

The first thing I noticed was that the needle was at its highest point no matter what. Meaning, that it doesn't take much for the expansion tank to be full.

I ended up replacing the cap anyways because I noticed that the new cap had two rubber seals that were in far better condition that the old cap. I believe the leak near the tank is now gone.

However, I notice a very minuscule coolant leak from one of the thermostat hoses. I haven't been able to check exactly where it's coming from but if you are facing the car, I think it's the hose LEFT from the thermostat. (If you are sitting in the car it would be the hose that is connected on the passenger side)... It's not a major leak but something to keep an eye on.

I am predicting I will have to do the full engine cooling system maintenance in the spring/summer. I just gotta get the parts first, part of me does NOT want to replace the radiator though. It's too much work imo to take it out but I haven't decided.

awdrev 01-18-2013 08:55 PM

FOUND the leak! It looks like it's the temperature sensor, I will be replacing it hoping that it's just that but I fear that the house should be replace as well.

I'll deal with that at another time. I think a new sensor will fix the leak, I noticed after looking at the sensor on eBay that the sensor has a rubber grummet which I believe it's the cause of the problem.

mlukas161 01-19-2013 05:12 AM

Congrats! Yeah that o ring can be a problem. Glad you figured out where the leak was coming from!

awdrev 01-19-2013 12:50 PM

Replaced the temperature sensor. The rubber grommet seemed to be really worn out so I hope the new one seals the gap better.

*crossing fingers*

awdrev 02-02-2013 12:04 PM

So I changed the Cap a couple of weeks ago and it's still leaking. This is borderline annoying right now, the tank was bought BRAND NEW from the BMW Dealership. I am afraid they won't exchange it but I will try calling them or contacting them.

* I checked all hoses, they all seem fine.

The leak comes right from the top but it's minor, it's enough to build up and stay on top of the tank... the layer of the liquid fluctuates but you can def see it.

Like I said, this is just annoying. I'm already thinking I have to change it again and when I did it last month, it was messy messy.


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