thetonka

I have a 2009 R320 Bluetec with 112,000 miles on it. Recently I had some problems with the cooling system, which I have posted reference to elsewhere. The top radiator hose exploded, the radiator popped a hole and leaked, and the coolant line for the EGR and heater blew up at the "T".

All repairs have been done at a local indie. Now it is leaking again. The indie says it is the oil cooler and that it is leaking a lot from the back of the engine near the top. Everything I have found to help my understand this engine makes me question this diagnosis. There is no coolant in the engine oil, and no other mechanics I have talked to have come across a failing oil cooler seal that leaked coolant.

The oddest thing is it seems to be intermittent. I can drive 3-4 days with evidence of any leak, then one day a big puddle under the car and the "Top off coolant" light comes on.

I tried to crawl under and see if I could get pics with an endoscope but could not find any evidence of a leak. If I can not figure this out I may take it to the dealer and see if they are more competent at a diagnosis.

Any help or suggestions would be appreciated.

Thanks

Plutoe

Your indy may be referencing the oil\water heat exchanger that is located under the charge air manifold---that assy has two figure eight seals that are prone to coolant leak.

Let's hope not because we love these jobs----loads of labor=huge expense related to the parts cost of six bucks!!

PS: Watch out for the Polak spammer who may post telling you he has done the job many times and its a DIY---he's an idiot!!

thetonka

That's the cooler they are taking about. Looking at drawings I would expect if there is a coolant leak in the cooler in the valley there would be coolant in the engine oil. It appears there are passages that could drain back into the engine.

thetonka

Thanks for the warning.

Plutoe

Further, if you look at the coolant documentation for the 642 in mod 164 and 251 there is an elaborate coolant de-oiling process in AR2000P1250GZB entitled "remove oil from cooling and heating system"----someone obviously planned for issues with oil contaminating the coolant system!!--not a simple process for a crappy design(my opinion)!!

thetonka

Yikes. Not cool.