Help with unidentified coolant leak, [pics included]

Originally Posted by WDE46

Indeed. I don't understand that.



The part number will always be the same. The manufacturer may not be. $45 was probably a Meyle unit. The "Genuine" part runs about $80. I don't know who the OEM is.


I just discovered the multiquote button. Holy ****.

M-M-M-M-MULTIQUOTE

Probably Meyle. And correct the part # will be the same.

CoolXpert, AFAIK, is the OEM for our Genuine tanks.

Originally Posted by E46Mango

Probably Meyle. And correct the part # will be the same.

CoolXpert, AFAIK, is the OEM for our Genuine tanks.

So today resulted in all bad results. I put in my new expansion tank, and 2 things happened:


The bleeder valve that I siliconed back together with high temp durable silicone bent a little bit too much when putting the new ET in when it hit something, and water began to spill out all over the place. Now I definitely need to order that.

The lower hose that connects to the bottom of the ET appeared as if it was leaking water out of the part of the hose just after its main connecting clamp to the ET. So now I'm back at square one, where I guess I don't even know what the problem is, because I broke my bleeder valve after I got towed back to home, not while the original coolant leak happened. If it wasn't the ET, which to my eye had no holes or cracks or anything that would lead to coolant pouring out at the same rate I poured it in, and my bleeder valve was perfectly fine until I tried to remove the ET after the overheat, then I have no idea what the problem is. The lower hose looked okay, but I couldn't tell if it was leaking water, or if the water leaking from the bleeder valve was simply trickling along the hose and condensing at a point and then beginning to fall. I don't know I'm out of answers.

The culprit is the hose that connects to the bottom of the ET and runs towards the back of the engine! It had about a 1" major laceration in it right where I thought it would. It appears to have rotted from the inside out.

Does anybody know the proper name of this hose? Or a diagram I can look for it? Thanks guys

Originally Posted by bostonsc4

The culprit is the hose that connects to the bottom of the ET and runs towards the back of the engine! It had about a 1" major laceration in it right where I thought it would. It appears to have rotted from the inside out.

Does anybody know the proper name of this hose? Or a diagram I can look for it? Thanks guys

I think it is #5 here:



Part #: 11531436410

Get familiar with RealOEM.com. Get the last 7 digits of your VIN and look around. You can learn a lot about your car with this site.

Originally Posted by bostonsc4

The culprit is the hose that connects to the bottom of the ET and runs towards the back of the engine! It had about a 1" major laceration in it right where I thought it would. It appears to have rotted from the inside out.

Does anybody know the proper name of this hose? Or a diagram I can look for it? Thanks guys

That's the hose I told you was likely the issue in my first post on the first page.

...and just as I predicted you found out quickly it wasn't the ET.

Sorry to hear you mangled the bleeder valve. It's always gotta be something, right?

Great news everyone, BMW had my hose in stock. Picked it right up 2 days before I'm supposed to drive 80 miles home for Christmas break! I installed the new hose, and JB welded my ET bleeder screw back together and let it sit for 24 hours before installing. This thing is like cement. I installed everything, but everything back together, and added coolant. I bled the system as properly as I know how, by leaving the cap off and letting the fan run at low speed at 91* for about 15 minutes while bubbles came up and out of the system. Car got to running temp, and stayed!!


- Took a while but my heat inside the cabin returned. I do have full heat right now.
- Took the car out for a drive nice and slow to see if my repairs could withstand the pressure, and they do!
- Only thing is though, I'm getting an intermittent low coolant light in the dash. Car ran for 45 minutes and didn't overheat, I inspected my work and everything is bone dry.
- What do you guys think about the coolant light? I'll add some more coolant once she cools down in a few hours and see if that helps.

Originally Posted by bostonsc4

Great news everyone, BMW had my hose in stock. Picked it right up 2 days before I'm supposed to drive 80 miles home for Christmas break! I installed the new hose, and JB welded my ET bleeder screw back together and let it sit for 24 hours before installing. This thing is like cement. I installed everything, but everything back together, and added coolant. I bled the system as properly as I know how, by leaving the cap off and letting the fan run at low speed at 91* for about 15 minutes while bubbles came up and out of the system. Car got to running temp, and stayed!!


- Took a while but my heat inside the cabin returned. I do have full heat right now.
- Took the car out for a drive nice and slow to see if my repairs could withstand the pressure, and they do!
- Only thing is though, I'm getting an intermittent low coolant light in the dash. Car ran for 45 minutes and didn't overheat, I inspected my work and everything is bone dry.
- What do you guys think about the coolant light? I'll add some more coolant once she cools down in a few hours and see if that helps.

When the bubbling finished, and you screwed the bleed screw back in, did you pump out the extra coolant from the expansion tank so your coolant was at the correct level? I missed this step the first time and had issues, usually accompanied by the coolant light.

Originally Posted by Schlag96

When the bubbling finished, and you screwed the bleed screw back in, did you pump out the extra coolant from the expansion tank so your coolant was at the correct level? I missed this step the first time and had issues, usually accompanied by the coolant light.

It was interesting because when I had the bleed screw open, the level shot way down and emptied the ET, then returned when I would tighten the bleed screw. So basically I just waited, added coolant, pumped some out until the level was at the correct amount while the screw was closed. I'm assuming an air bubble or something passed by the sensor that I didn't get 100% out? I'm feeling good about the coolant level though because I do have heat, and usually thats the first thing to go, no?

Edit: When I put the cap on and took it for a drive, it was after about 10 minutes had gone by where the level in the ET had no bubbles emerging.

I'm not sure what you did from reading that, but you need to remove the screw, fill till it's done bubbling out (I massage the upper hose a bit), screw in the screw, then pump out the ET till it's at the right level.

Don't forget that while you're filling and bubbling the heat needs to be on and set at 91.

If you do all that correctly, you shouldn't have any issues. If you still do then your system is compromised in some way.

Originally Posted by Schlag96

I'm not sure what you did from reading that, but you need to remove the screw, fill till it's done bubbling out (I massage the upper hose a bit), screw in the screw, then pump out the ET till it's at the right level.

Don't forget that while you're filling and bubbling the heat needs to be on and set at 91.

If you do all that correctly, you shouldn't have any issues. If you still do then your system is compromised in some way.

So major setback today; car ran great all day yesterday and today, until I got back to campus. I had a spike in engine temp that quickly returned back to normal, and when I get back I see a small puddle of coolant on the ground. Upon further investigation, turns out the hose I just replaced may not be on tight enough to the ET, cause thats where all the drip and steam was emerging from. I went to loosen the bleeder screw to relieve some pressure, and the head of the bleeder screw sheared off. Whats left is the bleeder screw section still present in the upper hose, but with a pin hole in it that came off with the head of the screw. I'm forced to to jb weld the pin hole there. I'm currently waiting for my engine temp to go down a bit so I can put this hose on tighter. Its a nightmare

First of all, get a brass bleeder screw. Idk why you're screw would be on there so right but oh well. Pick up a brass one and never look back.
I also recommend going easy on making it so tight. Just screw it in gently till it stops.
If I'm remembering correctly the lower hose should click into the expansion tank. There's a wire clip that snaps into the tank. If the snap doesn't engage a leak is inevitable.

Stop JB welding stuff. Also make sure the hose securely clicks into place and the clamp clicks into places as well. did you get an aftermarket hose? some have crappy seals

Originally Posted by E46Mango

Stop JB welding stuff. Also make sure the hose securely clicks into place and the clamp clicks into places as well. did you get an aftermarket hose? some have crappy seals

The hose I got right from a local BMW dealership. The metal bracket clicked in nice and securely yesterday, and the car ran great. Today thats where the bubbles and steam was emerging from. I plan to replace everything that I have fixed with JB weld over Christamas break, but the reason JB is in use right now is because my campus literally kicks everyone out for christmas break and fines you for any extra time there past 6pm tomorrow, so I'm doing the best I can to make my car driveable to get home. I've took the hose off, and rammed in on the ET nice and hard and securely, and reclipped that metal bracket around it. Just gotta wait for the JB to cure a little longer over the pin hole in the bleeder screw and then I'll add the coolant I lost, re-bleed, and hopefully be able to make it home tomorrow.

Originally Posted by peytonracer4

First of all, get a brass bleeder screw. Idk why you're screw would be on there so right but oh well. Pick up a brass one and never look back.
I also recommend going easy on making it so tight. Just screw it in gently till it stops.
If I'm remembering correctly the lower hose should click into the expansion tank. There's a wire clip that snaps into the tank. If the snap doesn't engage a leak is inevitable.

Will be picking one of these up first and foremost upon returning home. Thanks for the advice, I will be careful around it. However, I got a new OEM hose from BMW, shouldn't it have come with an O-ring of some sort? Mine did not. Hoping that isn't the reason for the leak

I had to put a fair amount of plumber's tape on the part sticking out of the ET to seal off the leaking connection in that very spot.

We got cabin heat, sustained 12 o clock engine temp, no low coolant light, and so far nothing leaking again. Took if for a few laps around campus just now, brought it to 3k rpm, (does increased rpm increase coolant pressure?) I just want to make sure that if I'm going 72 tonight on the highway at 3k rpm it won't blow my repairs, if so I'll go 45 I don't care. I have bled the system 4 times today, with the last time having no bubbles. When I cold start it however, the ET has been very low the past 2 times, so I'll add one more cycle of coolant to it before I head out. I have an 80 mile drive until I'm in the safety of my home where I have all the time in the world, lets just HOPE that my holds don't blow on the highway tonight. Thanks for everyone who helped me all along!

no, rpm doesn't have a direct effect on coolant pressure, but the more heat is generated by the engine the higher the coolant temp is, and with constant volume you get increased pressure.

you shouldn't be filling the coolant that many times. I think you're still leaking. You have any wet spots under the ET?

No wet spots on the ground or below ET. In total I've put about about 2 gal of coolant into it. Just a rough estimate. As long as my 2 lower hoses on the ET don't spew at their connectors I should be all set.

After 7 hours of work today a coolant hose lets go an all my hard work is all over the pavement. I fvcking can't handle working on this anymore. Now I'm forced to leave the car 80 miles from home until I can get a ride back to school to try this bullshit all over again. I think I need to take out the expansion tank to put this hose on any tighter.

You should consider investing in a pressure pump so you can do a pressure test whenever you do a work on the radiator. E46s are vulnerable when it comes to fluid leaks, at least in my experience. I have replaced the expansion tank 3 times, the whole hose assembly once, even the cover thingy at the back of the engine and the water pump too. Have you replaced the oil and tranny cooler? You dont want the coolant or tranny fluid to go inside the engine