[MTK24]

In the past 20k miles I have replaced the water pump, radiator and hoses and now, I have a coolant leak that started slow and is getting worst. Puddles on the ground when I leave the car in the garage overnight.

I took it to a shop that did a pressure test on the coolant and at 17 psi nothing leaked.

He said its the transmission cooler as it had dried anti freeze all around it and it was coming from that area. part number 17217536929

http://www.realoem.com/bmw/enUS/show...diagId=17_0319

I have never heard of this part failing. Does it come with a separate gasket you have to order? Does anyone know the part number to the hose it connects to?

[Basedtiger]

I had a similar coolant leak in the past. The transmission oil cooler hose that connects to the radiator was loose. All I did was tighten the T20 or T25 screw. I would also see puddles of coolant under the front left side of the car. If you wobble that small hose around you can see that the coolant drips on to the transmission oil cooler itself. It may appear like the cooler is leaking but a loose hose was the culprit for me.

[MTK24]

Originally Posted by Basedtiger

I had a similar coolant leak in the past. The transmission oil cooler hose that connects to the radiator was loose. All I did was tighten the T20 or T25 screw. I would also see puddles of coolant under the front left side of the car. If you wobble that small hose around you can see that the coolant drips on to the transmission oil cooler itself. It may appear like the cooler is leaking but a loose hose was the culprit for me.

thanks for the response

I just don't want to spend $300 on an transmission cooler and $150 for a new hose..

wouldn't a pressure test show show the small hose leak from the radiator though?

[Amitt]

Check to see if the water pump housing is cracked. I had a hairline crack in the seam of my water pump, which tends to happen to a lot of people.

[MTK24]

Originally Posted by E92_Amit

Check to see if the water pump housing is cracked. I had a hairline crack in the seam of my water pump, which tends to happen to a lot of people.

It would of showed coolant leaking in pressure test if it was. Also no coolant by water pump area. It is in drivers side right on the transmission cooler.

[TheMidnightNarwhal]

Originally Posted by Vampire335i

In the past 20k miles I have replaced the water pump, radiator and hoses and now, I have a coolant leak that started slow and is getting worst. Puddles on the ground when I leave the car in the garage overnight.

I took it to a shop that did a pressure test on the coolant and at 17 psi nothing leaked.

He said its the transmission cooler as it had dried anti freeze all around it and it was coming from that area. part number 17217536929

http://www.realoem.com/bmw/enUS/show...diagId=17_0319

I have never heard of this part failing. Does it come with a separate gasket you have to order? Does anyone know the part number to the hose it connects to?

Is there actually coolant that goes in the transmission cooler? I just thought transmission fluid runs through that?

[Emilime75]

Don't mean to offend your intelligence, but going to throw it out there, anyway...people have mistaken washer fluid for BMW coolant because of the similarity in viscosity and color.

Are you having to top of your coolant? You haven't mentioned any other symptoms aside from a puddle.

[MTK24]

Originally Posted by Emilime75

Don't mean to offend your intelligence, but going to throw it out there, anyway...people have mistaken washer fluid for BMW coolant because of the similarity in viscosity and color.

Are you having to top of your coolant? You haven't mentioned any other symptoms aside from a puddle.

Yes. I top it off every three days of driving.

[Emilime75]

Gotcha. Scratch that thought, then.

How about this one...you might need to find a way to get the thermostat open while doing a pressure test, or just let the car idle until it gets hot, under pressure and thermostat open while inspecting for leaks. Would also be good to remove the belly pan to get a better idea of what general area it's coming from.

[MTK24]

Originally Posted by Emilime75

Gotcha. Scratch that thought, then.

How about this one...you might need to find a way to get the thermostat open while doing a pressure test, or just let the car idle until it gets hot, under pressure and thermostat open while inspecting for leaks. Would also be good to remove the belly pan to get a better idea of what general area it's coming from.

The car was warm when doing the pressure test as I drove 40min to get to the mechanic.

The belly pan was removed. Thermostat and water pump showed no signs of leak at 17psi.

Nothing leaked from any of the hoses.

The bracket that holds the transmission cooler is missing though. The radiator was replaced under CPO 20k miles ago. Who knows what these mechanics fucked up on

[Emilime75]

Just thought since the thermostat is electronic it could've been closed during the pressure test, meaning that the entire cooling system may not have been pressurized during the test.

[AM330i]

Originally Posted by Emilime75

Just thought since the thermostat is electronic it could've been closed during the pressure test, meaning that the entire cooling system may not have been pressurized during the test.

there will be pressure on both sides whether the thermostat is open or closed

[Basedtiger]

Originally Posted by Vampire335i

thanks for the response

I just don't want to spend $300 on an transmission cooler and $150 for a new hose..

wouldn't a pressure test show show the small hose leak from the radiator though?

I would remove the intercooler and wiggle that hose around. In my case my car wouldn't leak at idle either, even when already warm. My theory was that the hose would move with engine vibration / road bumps and would get all components around it wet. Once you come to a complete stop that is when you can visually see the coolant drip down.

[MTK24]

Originally Posted by Basedtiger

I would remove the intercooler and wiggle that hose around. In my case my car wouldn't leak at idle either, even when already warm. My theory was that the hose would move with engine vibration / road bumps and would get all components around it wet. Once you come to a complete stop that is when you can visually see the coolant drip down.

Thanks I'll check this out. Do you have a part number for it?

I'm on REAL OEM right now trying to find it.

[prican_2000]

Did you ever resolve this leak?

I also have an issue with a slight leak that i am having a hard time trying to find but it is in the front Driver's side looks as if its leaking from the Intercooler.