Have a cooling system leak? Read this first.

Just want to let everyone know that if they have a cooling system leak, don't start wasting money by doing a complete cooling system overhaul because it may not be required. I just spend about $300 on cooling system parts and my leak was not been resolved. This is a very pesky leak that only appears under high pressure and cannot be found. Had I spent some money on a pressure test I would of known that I didn't need to spend $160 on a new radiator plus the time to mess around with it. I think I have found the leak, and I believe its coming from the mounting plate on the radiator, and none of the cooling system DIY guides replace this piece. If your doing a overhaul, save yourself the headache and order this piece as swell. Its plastic and its bound to crack just like the expansion tank. Its Friday night and I'm pissed off my leak hasn't been resolved.
Another issue that I just ran into is that the car is not monitoring the coolant level. The expansion tank is pretty much empty and the light is not on. (leak worsened over last couple of weeks) and the light hasn't been on for the last week. Usually it comes on almost every other day. I installed a new level sensor and the car isn't picking up on low coolant. I hope the wiring harness isn't busted from all the coolant leaking on it.

Here are the part number(s) is any one decided to take my advice.

Automatic Transmission
17111436251

Manual Transmission
17 11 1 436 250

Good luck, and again, GET YOUR CAR PRESSURE TESTED IF YOU HAVE A LEAK.

I think this part is causing a leak on my car. Check out the pics:




I found it on BMWMercedesparts.com for about $40, so the cost isn't too bad. I just did the ET and lower hose too damn it and it is still leaking! BMW Coolant isn't cheap

The leak looks like to be a faulty seal between the blue screw and the plastic piece, and according to this, you must order the entire bracket to replace it (#16, manual trans part)!!

I'd get it pressure tested. It could be leaking from above somewhere and dripping down and making it seem its leaking from below.

I'll get the pressure test done too, but for the long term it won't hurt to get the pieces.



I just pulled the trigger on the part # you suggested and a few others. The part # you referenced is $39.78 @ bmwmercedesparts.com

Here is what I got:

1 Collision Catalog - 2001 - BMW - 3 Series Coupe
Cooling, Radiator and components, Bleeder valve, Manual trans, Manual trans - 325ci & 330ci - 325ci & 330ci $0.00 $2.45
1 Collision Catalog - 2001 - BMW - 3 Series Coupe
Cooling, Radiator and components, Mount bracket, Manual trans, Manual trans - 325ci & 330ci - 325ci & 330ci $0.00 $39.78
1 Collision Catalog - 2001 - BMW - 3 Series Coupe
Cooling, Radiator and components, Level sensor, Level sensor - 325ci & 330ci - 325ci & 330ci $0.00 $14.58
1 Mechanical Catalog - 2001 - BMW - 3 Series Coupe
, Fuel filter, 325 and 330i, ci, xi, w/pressure regulator $0.00 $63.61
Sub Total: $120.42
Tax $0.00
Shipping TBD*
Total: $120.42

I believe I have the same exact leak.

I changed my expansion tank a couple of months ago only to now discover the leak.

How is the expansion tank supposed to sit on this bracket. Is there supposed to be a gap on the left where the expansion tank sits on?

I noticed if I try to press down on this side it would start leaking.

Do does it look like I have it seated correctly? I don't want to go by this bracket if I don't have to.

what do you mean by gap on the left?
if the expansion tank is correctly seated you shouldnt be able to wobble it around.
do you have mt or at?

Originally Posted by TrickTizzle

what do you mean by gap on the left?
if the expansion tank is correctly seated you shouldnt be able to wobble it around.
do you have mt or at?

It is a MT - new with new O-rings

The small hole in the far rear of the picture would leak.

Ok - I think that is the issue then. I can't move the expansion tank. But I am able to move/flex the bracket a little.

So how would I know that it is seated correctly? Is it supposed to snap in? I've tried to push down on the expansion tank as much as I can but it won't budge.

Are you supposed to push up on the mount?

Here's a vid. As I push that part of the mount up - it begins to leak coolant. The only way to stop it is if I pull down on it.

All,
When I did my cooling system overhaul I decided to remove the ET bracket because my automatic transmission thermostat broke and was being a ***** to remove whole. I figured if I remove the bracket I'll be able to remove the tstat plus install the ET on the bracket and install as an assy. What I did not know was that the bracket has an Oring that seals an opening in the radiator. Upon assembly this Oring of course leaked. I ran over to BMW to replace the Oring only to find you cannot replace the Oring you must purchase the entire bracket ($89 or $59 for BMW CCA members). I highly recommend purchasing the Bracket assy as part of the overhaul especially if you have an auto tranny and are replacing the tranny tstat. I am not sure if the bracket requires an Oring for manual trannys so you might want to look into that.

One little part like an O-Ring...

Anyone else able to make their expansion tank leak like what is see video

Hey, I had the same issue, me and another member fixed it, take a look.

http://forum.e46fanatics.com/showthr...339&highlight=

Originally Posted by phamine

It is a MT - new with new O-rings

The small hole in the far rear of the picture would leak.

Ok - I think that is the issue then. I can't move the expansion tank. But I am able to move/flex the bracket a little.

So how would I know that it is seated correctly? Is it supposed to snap in? I've tried to push down on the expansion tank as much as I can but it won't budge.

Are you supposed to push up on the mount?

Here's a vid. As I push that part of the mount up - it begins to leak coolant. The only way to stop it is if I pull down on it.

Your radiator mounting plate isn't snapped in correctly. Happened to me also.
I ended up taking everything out including the radiator and putting it on a work bench and sat there getting the mounting plate to work.

Did you buy a new radiator? If so what brand.

Originally Posted by TrickTizzle

Your radiator mounting plate isn't snapped in correctly. Happened to me also.
I ended up taking everything out including the radiator and putting it on a work bench and sat there getting the mounting plate to work.

Did you buy a new radiator? If so what brand.

Scratch that, doesn't seem to be the mounting plate because the mounting plate & radiator connection is towards the bottom.

In the video it seems like its coming from the drain plug...

It's leaking from this point.

I guess I have to drain everything and remount this off the car?

Yup the ET didn't seat correctly.
There is a notch on the et towards the top, make sure that rests on the mounting plate, and dont worry about the et being perfectly straight. it can be a bit crooked as long as it seats correctly and doesnt move.

What a horrible design, no wonder why BMW scrapped that design and improved the simplicity on the newer BMWs.

Having the same exact problem. Anyone know if this needs to replaced or removed from the car to install probably. It was leaking before I installed the new expansion tank so Im assuming its shot and not a mounting issue. Is there a o-ring on the piece? I know there is one on the new expansion tank.

Originally Posted by phamine

It is a MT - new with new O-rings

The small hole in the far rear of the picture would leak.

Ok - I think that is the issue then. I can't move the expansion tank. But I am able to move/flex the bracket a little.

So how would I know that it is seated correctly? Is it supposed to snap in? I've tried to push down on the expansion tank as much as I can but it won't budge.

Are you supposed to push up on the mount?

Here's a vid. As I push that part of the mount up - it begins to leak coolant. The only way to stop it is if I pull down on it.

Bookmarked for later.

I'm pretty sure I have a sneaky leak that only occurs overnight after the car has been run all day. Someone on another forum pointed out that it could be a rubber O-ring.

Originally Posted by phamine

I believe I have the same exact leak.

I changed my expansion tank a couple of months ago only to now discover the leak.

How is the expansion tank supposed to sit on this bracket. Is there supposed to be a gap on the left where the expansion tank sits on?

I noticed if I try to press down on this side it would start leaking.

Do does it look like I have it seated correctly? I don't want to go by this bracket if I don't have to.
]

I have a similar leak from this location but can't tell extactly where. When I replaced my radiator I noticed of the 2 openings under the ETank, the bigger opening had an O-ring. The smaller opening did not have an oring. Does anyone know if there should be an o-ring there also? I'm starting to wonder if this is where the leak may be coming from. See

For some reason, I think the ET bracket had an o-ring on the smaller port that fits into the ET.

But, BM, if you just did the radiator, the other possibility is that you either got the radiator for the wrong car (manny and auto rads. are different if you got the Behr)...or if you got OE radiator, then there's a leveling screw that changes it for manny/auto.

There've been a number of posts where the leak comes down where you're seeing it (sort of)...and it's from the radiator itself.

HTH...don't hate me! I'm just a messenger!