Mysterious coolant leak from bottom left side - help!

[fatboy613]

Hello,

My car has a coolant leak coming from the front bottom left side, near the coolant hose junction that connects to the aluminum oil cooler. When the car is running, it leaks very badly from that oil cooler and the plastic hoses shown in the picture. I can see that the rubber hose has part number 06e121030a. Does anyone the part number for the plastic coolant pipes that the rubber hoses connect to? Or where they go up to? I'm trying to follow their location but it's pretty tight down there....
https://imgur.com/a/bhsfOSv
https://imgur.com/a/bhsfOSv
Thanks!

Edit: So I managed to find the part number for the pipe, it is 06E121044AE (part #13 on this diagram: https://parts.audiusa.com/a/Audi__/49372356__6477584/HOSES--LINES/1330080.html), so now my question is where does this pipe go? To the top of the engine? Backwards? Does it connect with the front crossover pipe?

[Burnt]

Let us know. I've been having low coolant issues, can't find the leak, but can smell it everytime I get out. Having to fill every 1k miles with distilled/coolant, fair amount, passes the minimum line from max

[Valpo A7]

Back left and low on the engine is the location for the N509 valve. Its a coolant bypass solenoid that sends coolant to the trans cooler. Common failure on the platform. The seal will fail and flood the electrical connection but you should get a code with it. Worst case scenario with this failure is for coolant to wick up the electrical connection and migrate the insulation into the mechatronic.

$62 from FCP or almost $200 from the dealer

https://www.fcpeuro.com/products/audi-heater-control-valve-febi-4h0121671d

[fatboy613]

Back left and low on the engine is the location for the N509 valve. Its a coolant bypass solenoid that sends coolant to the trans cooler. Common failure on the platform. The seal will fail and flood the electrical connection but you should get a code with it. Worst case scenario with this failure is for coolant to wick up the electrical connection and migrate the insulation into the mechatronic.

$62 from FCP or almost $200 from the dealer

https://www.fcpeuro.com/products/audi-heater-control-valve-febi-4h0121671d

Thanks, I don't have a code for that currently, but I'm going to be changing this soon as preventative maintenance. However the leak is coming the front left side of the engine, there are a bunch of coolant hoses close to the aluminum oil cooler (I think that's what it is?). The part number for the leaking pipe is 06E121044AE, it seems this pipe goes up and connects to the coolant crossover pipe and it's leaking pretty badly somewhere. Just installed a new crossover pipe with new thermostat/pump/PCV so these shouldn't be leaking.

I guess my question now is, has anyone replaced this before? I downloaded the repair manual from erwin and it calls for removing the AC compressor and motor mount I think.... Seems a little excessive to me

[fatboy613]

Let us know. I've been having low coolant issues, can't find the leak, but can smell it everytime I get out. Having to fill every 1k miles with distilled/coolant, fair amount, passes the minimum line from max

Do you see any coolant leaking? If not, I think you might need a new PCV

[HolyHell]

I would recommend acquiring a pressure tester to help pinpoint the leak first instead of replacing stuff, could just be a $6 clamp. Also re-check your work just in case.

[Burkeomatic]

Thanks, I don't have a code for that currently, but I'm going to be changing this soon as preventative maintenance. However the leak is coming the front left side of the engine, there are a bunch of coolant hoses close to the aluminum oil cooler (I think that's what it is?). The part number for the leaking pipe is 06E121044AE, it seems this pipe goes up and connects to the coolant crossover pipe and it's leaking pretty badly somewhere. Just installed a new crossover pipe with new thermostat/pump/PCV so these shouldn't be leaking.

I guess my question now is, has anyone replaced this before? I downloaded the repair manual from erwin and it calls for removing the AC compressor and motor mount I think.... Seems a little excessive to me

I had one of those go out, my car threw a code, but no leak or no coolant creep up the wires. I was proactive about it though. When I was investigating the problem I found a spectrum from leak and severe coolant migration with no code to mine where there was a code and no damage.

If you don't want to shotgun approach things, I would suggest just dropping those panels and inspecting everything well. If you want to have some parts on hand to change things if needed, I wouldn't fault that. It could just be the hose too, but I doubt it.

[fatboy613]

Update: turns out that the rubber seal fell out of the front crossover coolant pipe during installation....