Hello everyone,

I have a 2008 C30 with 211,000 km on it. This past summer I broke down when all my coolant leaked out from the red radiator plug with out me noticing. I got that fixed, but kept seeing coolant leak under my car, and having to top up my reservoir tank. After 4 trips to the same mechanic, the car is still leaking coolant.

It leaks when cold + high pressure (i.e after driving it to operating temperatures then leaks as it cools overnight). It does not leak if I depressurize the system before the engine cools all the way to leaky temperature.

I am playing coolant leak whack-a-mole. Every time I close off one leak, it starts leaking elsewhere.

Does anyone know what might be going on? This never happened before in the 5 years I owned the vehicle, and now all of a sudden it is finding every possible avenue to dump coolant overnight.

the most recent leak is under the engine, towards the back, from what looks like some kind of drainage plug. I could probably get this tightened but I worry it will just start leaking elsewhere.

Attached is an image of the most recent leak site.

 

Maybe time to have a (new) pro shop do a pressure test and measure the system pressure with the engine running. Do the hoses feel rock hard when the engine is warm? A few things could be in play - a) head gasket / warped head issue. Need to see if exhaust gasses are pressurizing the cooling system creating leaks in older weak components b) the original leak source was not properly identified. (say a hose under the reservoir or a crack in the reservoir a freeze plug in the block etc) c) the radiator core has some clogging and the system is actually running hotter than normal (not sure if you have a temp gauge in the car - a shop can use a thermal gun to see if the engine is warmer than the gauges are reporting).

 

thanks for the reply. Some additional info: the shop has replaced the reservoir tank, the upper rad hose, some other hoses that I can’t remember.
the temperature gauge in the car is dead centre when running hot, no change there. And the tubes are hard when hot.

thanks again I’ll look more into those things. Probably will take it to the dealership at this point.

 

the shop should put a pressure gauge on the system to see if its normal. They can also pressurize the cooling system to see if they can produce the leak without poking around a hot running engine :-) If the system pressure with a running engine is too high, then the next thing is to test for head gasket issues.