Oh boy, here we go. Coolant leak that pressure test won't find. 202
 

I had a trans service at dealer and they said they noticed a coolant leak, small, but couldn't find source. Did a pressure test. I noticed some kind of leak that seemed like just water collecting in belly pan the week prior. Had some white crustiness on the main radiator hose, but they should have been able to detect if it was the source.

Surely it's not the head gasket. It was done under warranty at 80k/2 and a half years ago. Car now has 159k. Say it isn't so....

More like weeping cap tanks on the radiator. See a lot of crusty residue around top hoses at rad' . If the top hose is getting stiff it puts more strain on the neck assembly as engine moves under load and can loosen the tank seals.

Still......also could be a head gasket !:whistling2:



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That white crusty stuff is coolant, thats where the leak is probably coming from. I'd tighten the hose clamp a bit and see if that doesn't do it. Since the car is 10 years old if the hose is original it may be getting a bit tired. But 10 years isn't a lot for a Mercedes hose.

Radiator hoses rot from the inside out. Its common for a leak to develop from the inside to the fabric weave layer of the hose. The coolant migrates through the weave until it reaches the end of the hose where is escapes. Looks like the leak is at the end of the hose but it is really from inside somewhere. replace the hoses.

Interesting. The hose seems softer than it should, not harder, as I would expect with age. Rotting from inside out certainly would explain that one. I'll probably start with a hose and cross fingers.

Thanks