I’ve needed to add coolant 3 times in the last 6 months, so decided to do an inspection. I noticed pink coolant residue underneath the collar for the air intake cross and on some of the belt pulleys. I assume the leak is nearby, although I guess it could be lower in the system and being drawn up by the fan and belts (?).

Nothing obvious with the other coolant pipes/tubes, except for this little gray connector that ties into the coolant reservoir via the thin coolant line that runs along the top of the fan box.

Am I missing a tube or connector?

Any thoughts?


Coolant residue underneath the T - air intake crossover

Connector with no hose connected

 

You may want to check the plastic coolant pipes located below the supercharger. Very common to fail..

 

Thanks for the info. I haven’t had a chance to investigate the source of the coolant leak, but just got DTC warning light today. The code is P0128 – Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature).

Assuming the coolant leak and thermostat are related? Anyone replaced their thermostat housing?

 

So, i have (like many) replaced most of the plastic parts for the aluminum options (e.g. crossover pipes front and rear, thermostat housing and the tube connecting the pump with the oil cooler, etc.. )... i even decided to replace the o-rings on the aftermarket aluminum parts by high temp / chemical resistant ones.

 

I had the thermostat housing replaced when I needed new crossover pipes. See the attached photo for everything that was replaced.

 

Looking at both pictures, it looks like coolant is leaking around the (or from underneath) the tie-down strap on the pipe in the first picture. The water stains look like the liquid was blown back from that seal. The second picture looks like drip from the same seal. If water gets out, air can get in and cause temperature variance.

 

My dealer as well as a good independent shop both recommended using the aluminum parts but using the factory o-rings instead of the o-rings that come with the aluminum aftermarket parts. They both said this independently without my asking or mentioning what the other one said.

 

I'm just going by the pictures, which clearly suggest the leak is coming from that connection.
Perhaps both those shops determined a non-OEM hose is less likely to leak. That doesn't mean it will always cure the problem, or that their suggestion is wrong.

 

Will echo comments of others on potential leak source.

Curious - how many miles on your D5? Trying to get a gauge for when a leak may spring up on mine

 

mine started shortly after 65k miles approx.. car today is at 78k and currently replacing the rear crossover pipe (heater) for the Aluminum version.