[slattrick]

2008 bmw 328i. I replaced my coolant hose part number: 11537545890 about 2 days ago, it broke off and I replaced it. The next day I noticed a puddle underneath my car of coolant. I immediately thought that I did not install the part right or I did not screw the hose clamp tight enough. But after investigating it, the hose that I replaced is completely dry underneath, I jacked up my car and sat underneath it for a little trying to figure out where this leak is coming from. It is dripping from right underneath where the headers are, but the leak is traveling from some where because it is dripping off of my frame and control arm so I am unable to see the source because the frame is blocking the view. I did find a small leak however but I do not know if it is leaking at the rate I am loosing my coolant. It seems to be a small white seal underneath the oil filter housing. I attached pictures of the leak spot, my dirty engine bay and highlighted the seal that is in question. I will change my oil tomorrow, but I checked inside the oil fill cap and did not see any white frothy oil like a head gasket leak. And it is hard to tell if I have white smoke coming out the back because I live in the north east and it is fairly cold now. I can not tell if it is a head gasket, water pump or thermometer. But I would like to identify that seal that is leaking for sure. Thank you in advance.

[autoart]

The Mickie mouse flange on the block likes to break and the coolant reservoir also can crack.

[TriumphTim]

Yeah, he replaced that though. When I changed my flange, a section broke and stayed in the opening, I almost installed the new part over it. It looks like your is seated though.

Maybe the oil filter housing gasket if that high up on the engine?

The thin coolant pipe that that runs across the top of the radiator into the reservoir is very fragile, yours looks very old and corroded. I would replace that ASAP, that pipe left me stranded, it crumbled in my hand like the flange you replaced.

Otherwise, I would wipe down the engine completely and check again.

[slattrick]

Originally Posted by autoart

The Mickie mouse flange on the block likes to break and the coolant reservoir also can crack.

the mickey mouse flange was the hose that i replaced the other day, and i checked and i installed it correctly it’s not the thing that is leaking

[slattrick]

Originally Posted by TriumphTim

Yeah, he replaced that though. When I changed my flange, a section broke and stayed in the opening, I almost installed the new part over it. It looks like your is seated though.

Maybe the oil filter housing gasket if that high up on the engine?

The thin coolant pipe that that runs across the top of the radiator into the reservoir is very fragile, yours looks very old and corroded. I would replace that ASAP, that pipe left me stranded, it crumbled in my hand like the flange you replaced.

Otherwise, I would wipe down the engine completely and check again.

the pipe across the the radiator seemed to have been replaced, i don’t think the oem ones are made of copper, which this one is, i checked every visible hose and none are dripping coolant out, i will probably end up replacing all the coolant hoses that i haven’t replaced all ready, and will hope in doing so it will fix the leak or i can find the source of it in the meantime, i just have no clue

[Serf27]

Start the car and check where it’s leaking from once it builds up pressure.

[slattrick]

Originally Posted by Serf27

Start the car and check where it’s leaking from once it builds up pressure.

i did, for 15 minutes just sitting underneath the car, still couldn’t find it

[Serf27]

When you replaced the black fitting on the head, did you use a new o ring? If not, put a new one on. If you did, it’s possible it got pinched and isn’t sealing.
Also any debris between the fitting and the head could cause it not to sit and seal properly.
Does the new hose use the sealed clamps?
Maybe it is not clamped as tight as it could be.

Was the coolant full when you visually looked for leaks? If it was low and the leak is up high, possible you may not be able to see it.

I’d try this, top off coolant, let the car warm up and gently wiggle hoses around to see if anything starts leaking coolant.

There’s not many places around the top that could leak without being very noticeable.
Look at your coolant reservoir too.
I just replaced mine today. Hairline crack on the side that would only leak sometimes, and was hard to tell where the leak was coming from.

[slattrick]

Originally Posted by Serf27

When you replaced the black fitting on the head, did you use a new o ring? If not, put a new one on. If you did, it’s possible it got pinched and isn’t sealing.
Also any debris between the fitting and the head could cause it not to sit and seal properly.
Does the new hose use the sealed clamps?
Maybe it is not clamped as tight as it could be.

Was the coolant full when you visually looked for leaks? If it was low and the leak is up high, possible you may not be able to see it.

I’d try this, top off coolant, let the car warm up and gently wiggle hoses around to see if anything starts leaking coolant.

There’s not many places around the top that could leak without being very noticeable.
Look at your coolant reservoir too.
I just replaced mine today. Hairline crack on the side that would only leak sometimes, and was hard to tell where the leak was coming from.

I was not able to check today because it was raining, I do believe it is a lower hose that connects to my thermostat housing. I replaced the infamous mickey mouse hose as most call it and it did come with a new o ring that was in the mikey head, i believed i sealed it and i did not see any leaking from the top of the engine, because like you said it would be easy to see, i think after i installed the lower part of the house however (the one that connects to the thermostat) i may have not pushed it all the way up, or i might have disturbed another hose that is now leaking, i only drove my car to work this weekend and i noticed that the leak got significantly worse, due to that i believe it is a hose leak, not an internal leak such as my water pump or my thermostat itself, plus, i do not have any of the other symptoms of a failing water pump, i do not know the best way to go at fixing the hoses onto the thermostat however, it is very cramped and i can not access it from the bottom of the car, do you have any advice on the best to go at it? maybe removing the reservoir might help. thank you

[Serf27]

There is no way to access the water pump/hoses on it from the top. It has to be from the bottom.

I have found it a lot easier to unhook the sway bar by removing the mounting nuts on it.
It is possible you could have tore a hose that was about to fail when installing the new hose.

[Bmw1939]

UV Dye Kit?