kevm14

I was within a couple miles of home when I got the low coolant warning, and in my driveway when I noticed the temp gauge pegged and the A/C compressor shut off. Fortunately I never saw any further warnings commanding me to shut down the engine immediately.

Ever see this?







My assessment is the wire spring retaining clip rubbed through the (galvanized?) coating on the hose sleeve enough for it to rust. Enough rust built up over time that it created a jacking force against the retaining clip to come out of the locked position, which allowed the hose to pop off under pressure. So I'll replace the hose. $29 at my local dealer. https://www.mercedesbenzpartsshop.co...ose-2215013582

Looks like I can do it from the top, too. I started it to pull it on ramps after cooling for 10 minutes. The temp gauge wasn't pegged and it ran 100% normally so I'm sure I'm fine. I'm lucky I was able to make it home. Anyone seen this before?

BOTUS

I've not seen it, but it looks like u r correct - the corrosion allowed the hose to slip past the retaining clip

vettebk

Rust buildup and subsequent corrosion can exert a tremendous force on the hose and clamp. Remove the rust using WD40 or another water/rust solvent. Clean all of the connections well. Replace the hose and clamp with OEM or better (no Chinese parts). You should be good to go. Keep us posted.

Your only real risk is a possible blown head gasket from overheating which would result in more overheating at highway speeds when you complete the repair. If she runs cool after the repair, you should be good to go.

Senecat

Looks like it may not have been installed properly/completely in the first place!

kevm14

I guess that's possible. I have not touched this hose but I believe this car was in a front end collision of some kind in the past and could have needed a radiator. I did not order that retaining clip. Maybe I should.

EDIT: ordered clip. https://www.mercedesbenzpartsshop.co...spring-9931202

BenzV12

It could have been worse . Luckily , you got away with that . I also thought it was a poorly installed hose at first glance but replacing these should fix it .
Happy Driving

cruiser02

Wow! Very lucky you didn't drive more. At least now you can get some fresh coolant in her

kevm14

Was working with my friend all day yesterday on his new CLK550 but I snuck over to pop the new hose on.

Looking closer at it, the rust thing I described wasn't quite right. What actually happened is more basic: the groove where the retaining clip is supposed to clip into simply rusted away and there was nothing left.

Rusted end


The upper end (more like how it is supposed to look)


New hose needed a little WD-40 on the O-rings and it popped right in. Did a vacuum fill and it was done. Warmed it up and took it on a short test - everything is perfect.

I'm surprised I haven't seen this as more of a PSA. But considering the trips I have used this car on, this is scary. I may want to just do the lower hose. For reference this is an 07 with 102k.

Senecat

Couldn't have discovered this potential catastrophe under better circumstances. Good work.