Clk coolant leak

[clk320x]

Had coolant check light flash up, checked coolant and was just under half of tank. When engine warmed up and switched off and on the lift disappears.

Anyway when cold I poured in some 100% Antifreeze (from MB) and then the light disappeared.
What's worrying is this is the second time I've had to do this so there definitely is a leak.althought it's taken over a month atleast
Havnt been able to get to garage due to family reasons etc etc, anyone have any idea what it could be?
Checked oil and is crystal clear so hoping that rules out head gasket
Love the car so hoping it's something minor.
Anyone have any experience with similar issue? I'm sure I'm running over a 50:50 mix at the moment, can this harm the engine?
Cheers

 

[A250 Bennyboy]

I had a crack in the thermostat housing that only leaked coolant when it warmed up and the crack opened up from expansion, took an age to find the source of the leak, went though 10ltrs of G48 topping it up, when the source was eventually found it was replaced under warranty thank goodness.
Cheers
Ben

 

[dozypillock]

What year is this? ie 2002/3 vintage?
Mine had the classic "valeo" problem and the water can get into the gearbox oil through the Radiator.
May be worth checking before too many miles, or the gearbox gets damaged.

Neil

 

[PobodY]

It's probably just a pin-hole in one of the hoses; it doesn't leak until the system is at full pressure. If it sprays on to the exhaust you'll never see anything because it immediately evaporates.

 

[clk320x]

Dozy it's a 2003
W209 how would I check if it had a valeo radiator? Cheers

 

[clk320x]

What year is this? ie 2002/3 vintage?
Mine had the classic "valeo" problem and the water can get into the gearbox oil through the Radiator.
May be worth checking before too many miles, or the gearbox gets damaged.

Neil

How can I check if mine has a valeo? It's a 03

 

[alabbasi]

You can buy a pressure tester and test it. Once you apply pressure the leak will either show itself or not. If if it does not, likely to be an internal leak like a head gasket.

 

[KillerHERTZ]

Highly unlikely to be the Valeo issue after 13 years of use. Would have given up the ghost long ago.

 

[Auto-mobile]

Highly unlikely to be the Valeo issue after 13 years of use. Would have given up the ghost long ago.

I am still doing these, w220/w211 mostly.

To cross that off you list of possibilities you would need to get a glycol test on the transmission oil.

Waters pumps are another contender, you will see crystallised coolant at 6 o'clock below the pulley.