Coolant leak found - but what part is it?
 

For a couple of months, I've had a slow coolant leak on my CMS (2013, N18). Because it's been so cold here, I couldn't (didn't want to?) investigate too much. My commute is short and I checked the coolant daily and added a couple of ounces when needed. While doing an oil change today, I was able to do some detective work and I found a leak. It's where a very short hose meets a metal elbow, not far from the thermostat housing. I don't see the part on RealOEM. I have a vague memory of reading something about it here and that maybe the part was deprecated and replaced with a new version. Of course, now that I need the information, I can't find it. Does anyone know what it is? Really bad photo below.

My car has 67000 miles. So when I replace this part, I'm thinking of doing the thermostat housing, water pipe, and water pump (mine has the plastic housing). I figure I'm going to have to disassemble quite a bit so I might as well do a little preventive maintenance. Any thoughts?

Sorry for the quality of the photo. It's shot looking down but into a mirror so we're seeing the part from below. The leak is on the far end.
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I kept searching and finally found it: Coolant temp sensor elbow

The replacement part deletes that elbow and the temp sensor but requires the new thermostat housing so that answers the second part of my question as well. I'll need to replace the thermostat housing so I might as well do the water pipe and water pump too.

more looks like the water pipe ?

or maybe the elbow that is on the thermostat, but you will have to change the whole thermostat

Thanks. It is the old metal elbow with the temperature sensor. Just sent ECS more of my money for the replacement part plus the thermostat, new sensor wiring, and water pipe. Now to study the Youtube videos...

I just did my thermostat. that's when I found the one in the elbow was leaking on mine also. You can just pull the sensor and put some RTV on it. The O ring gets hard on them. The RTV is an easy fix. Sorry I didn't see this sooner.

Thanks, I appreciate the reply. I saw mentions of the RTV fix but mine doesn't appear to be leaking from the sensor, though I can't tell exactly where it's coming from. Since the thermostat is original, I thought it best to just get the new part that eliminates the elbow and replace the thermostat.

The parts arrived yesterday: thermostat, new wiring, and the replacement hose that deletes the elbow. It will be a couple of weeks before I have time to do the installation. In the meantime, I'm trying to figure it all out. I've watched a couple of the thermostat replacement videos but haven't seen one in which they do the elbow delete so I have a question. In this new hose assembly, what does the small end at the upper right connect to? It will probably become obvious when I start taking my car apart but, as I said, I'm trying to figure things out.

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