Pics: Coolant leaking - Maybe coming from yellow box next to radiator on passenger side?

[hskrdu]

Hi all! (Her) 2015 GSW (6M) has had its first issue. Routine drive on the highway, low coolant warning 20 minutes after departure from home.


(Days later, inspecting for source of leak. Dripping from yellow box on passenger side, high up, next to radiator).

Pulled over: Coolant bottle was low, engine temp was normal, so I added de-ionized water (did not have G13 with me). Steam was coming from bottom of engine, but the roads were not dry and I could not find the leak or determine the source of the steam (but I could smell the coolant). Engine oil on dipstick looked normal.

Later, tasks complete, no further low coolant warning until almost home- engine temp still normal. Coolant bottle was "empty" and later re-filled properly. Engine oil on dipstick looked normal.

A few days later, with a dry engine bay, I started the engine and inspected for leaks. After about five minutes of idling, with the engine temp gauge just starting to rise, I found coolant dripping from high up, next to the radiator, on the passenger side. After poking around and trying to trace it, coolant seemed to be coming from a small yellow plastic box, which sits to the side of the radiator, right next to the headlight housing, and is just a few inches below the highest point of the radiator. I kept looking for the "actual" source of the leak, as I didn't recognize this item as being part of the cooling system, but could not find any leaks above that yellow box. The coolant quickly pooled on the belly pan, and drips eventually scattered a bit, probably due to the accessory belt.

Questions:

Is it possible the this yellow box is the source of the leak, or did I miss the origin?
I can't find that yellow part in the self study guide or the online manual- anyone know what it is?
If it is not the source of the leak, but I can see the coolant collecting and dripping from the yellow box, are there any suggestions for likely sources?


(Click on picture for full size). (Passenger side of engine bay, looking towards the radiator. Highest point of coolant dripping appears to be the yellow box that sits between the rad hose and headlight wiring).


(Click on picture for full size). (Close-up of yellow box, orientation is same as photo above).

Thanks all!

 

[hskrdu]

Ok, given that it seemed quite unlikely that coolant would be flowing through a small plastic box or sensor housing, I'm guessing that it is leaking next to / nearby / just above that yellow box. A search for Mk7 radiator replacement gave me very little, but there are lots of Mk7 intercooler "upgrade" videos. This confirmed that the little yellow plastic item where the coolant is collecting and dripping is a "radiator mount."

Now, I was just about to order a new radiator and proceed to a repair, but for all 67 of you who have viewed this:

Q: Is there any way to confirm that it is the rad leaking and not the intercooler, prior to taking the front end apart and having the car offline while I wait 3-4 days for parts?
Q: If it is leaking from either the rad or IC near / above that yellow radiator mount, is there any other smaller/cheaper connection or tubing that might be the source of the leak, and can this be determined prior to taking the front end apart?
Q: If I have to replace the rad or IC, is there anything else that needs to be done (I think a few O-rings are required)?

Thanks all!

 

[hskrdu]

To all three of you who are interested, it's (of course) good to wait and confirm parts needed before buying, since it wasn't the primary rad but the rad for the intercooler- not sure if these have different names.

The leak was coming from a crack along a line between the black plastic radiator housing and the mount that plugs into the yellow plastic mounting piece. The leak developed very quickly, and is almost as if it was struck hard right at that mounting point, but there was no damage to the rest of the area that would reveal a significant blow. The pressure of the rad into the mount was keeping the crack "together" and when the radiator was removed, a chunk of plastic fell away, with the associated gush of coolant.

Would love to know the cause...

 

[Nuje]

Yeah - that is strange. That area (the yellow plastic thing) is hidden/protected by the bumper/grill, right? So, doubtful it was a rock or something like that from outside the car.
Was there any engine work done recently? Anything in the engine bay? Like, maybe someone used that as a leverage point to move something (?).

 

[hskrdu]

Right, it's as if someone hit with a hammer, but no rock (or magic hammer) could have struck that spot without leaving other damage.

No engine work- (she) is the original owner, and VW hasn't even seen it for phase 2 yet, so I'm the only one who has serviced it. She had the rear bumper cover replaced a year ago after a parking lot scrape (and honest other driver), but nothing to the front end.

That yellow clip that holds the AC condenser and two radiators has a rubber bushing inside to absorb movement, and it looked fine, and there was no other signs of stress.

It was not a slowly developing leak, there were only a few cumulative miles between first low coolant light and significant loss at the cracked area a few days later.

I'm guessing maybe a factory defect that revealed itself after a pothole or something, but really have no idea.

 

[adjat84th]

There are two versions of the charge air cooler radiator (hot climate and standard), one is a little thicker or wider..can't recall. Just FYI
Interesting place to leak for sure, maybe a really bad pothole jolted it just wrong?

 

[hskrdu]

I found two versions of a Rad for the Mk7 TDI: 5Q0-121-251-GL and 5Q0-121-251-HQ (which replaces HP). I think only one of these is for the IC, the other is the main engine rad. The one that went in was the HQ, as I didn't find other IC versions.

Pothole: It was suggested, but (she) didn't recall hitting anything memorable, and I think I might have been driving the very first time a warning came on, but before a leak was clearly visible- and I also don'r recall anything, but certainly possible.