Hi,

I have a CLK 320, recently acquired from an owner who hasn't kept service history records.

Just yesterday I replaced (at an indie mechanic) the water radiator due to a leak from the drainage where a crack was developed. After the radiator replacement, the coolant system was flushed with a specialized flush chemical and rinsed two times with tap water. New Mercedes coolant was filled in in 45%/55% ratio with distilled water.

The day before I also had oil cooler gaskets and filter housing gasket replaced with OEM parts at the dealer.

Today I noticed small, milky white washy (and snot like) spots floating on the surface of the coolant in the tank.

Could this be related to the two recent events/interventions, or a coincidence whereas the problem is likely elsewhere (head gasket, god forbid)?

Thanks in advance for your valued opinion.

 

After some spirited driving today I don't see the lumps no more, but some thin film of something transparent on top of the coolant fluid. Since nobody of the 50 people who read the post was able to advise, I guess anybody who ever searches the forum with a similar question would find no opinion on whether change of radiator and coolant fluid from red to blue could cause mixtures in the new coolant even after flushing the system. Nor if the oil cooler gaskets replacement can have any connection to oil getting into the coolant. Thanks anyway.

 

Usually thats a sign of coolant mixing with oil. take it back and have it pressure tested to see where the leak is coming from.

 

Couple of notes -

Could you post a photo of your oil cooler? I've heard from others who say they have an oil cooler on either a non-AMG M112 or M113 . I've seen one - in 2000, Car Magazine out of South Africa tested what they called a "CLK430 AMG" - it had a factory oil cooler. On a US spec W208, the oil cooler only came on a CLK55. BTW, oil cooler gaskets have nothing to do with the radiator.

In your second post you mention changing the fluid from red to blue. The only red fluid I know of is Dex Cool (closer to orange until it starts devouring stuff). If your old fluid was Dex-Cool, that may explain a lot of things. Dex-Cool has been known to destroy radiators, heater cores, water pumps, aluminum blocks, and gaskets. Do a search on Dex-Cool and Class Action Lawsuit. Regarding your coolant tank, the floating debris spots could have come from a number of places. ESPECIALLY if Dex-Cool was used. We know the radiator was changed, was the tank cleaned? If not, it could have had residue.

Lastly, did the INDY recheck and top off the transmission fluid?

 

Thanks guys.

@CJackson13: I plan of taking it to a mechanic, but I also want to prepare of what possibly I could hear back from them, perhaps eliminate some probable lies they may throw at me for money to bounce back.

Am I right to think that pressure test is done through the oil-pressure-test port bellow-left the oil cooler?

@MarcusF: I'm not based in the US. The car I believe is an European spec. I'm sharing a pic of the oil cooler in question for you. Used an existing photo I had of the engine on my car, with the cover on, just marked the part. Hope it's good enough for you.





Previous coolant was not the brand you mention, we don't have these in Bulgaria. It was a G12 spec coolant whose brand I don't know as the previous owner sold it to me with that (I presume it was "OMV") - red, almost pink. Now I had Mercedes OEM coolant in. The system was flushed and drained with water, but the Coolant Tank was not thoroughly cleaned itself, just whatever water was hosed in it during the system flush procedure.

Lastly, no recheck or top-up was done on the ATF after the coolant replacement. Why would you ask, what do you have in mind?


Milky white spots are not so obvious today after some 30 minutes spirited driving, only tiny washed-away spots remain, and I presume the more evident lumps burned out, but would return? Hesitant to get the car to a mechanic if there isn't much evidence to show as symptoms, I hope I don't, but got a feeling I'd have to return it for a pressure test... Still, I thought some miniature amount of the old red coolant may have remained somewhere along the hose connections or in some tank corners and if these different types of coolants mix - it would curdy the coolant in some clotted white blobs?

Cleared out that oil cooler hasn't have access to oil, for oil to get into coolant. So that's ruled out, Thanks!

BTW, mechanic told me new radiators come with some oil inside of them as part of rust-prevention from the manufacturer and that this oil would burn out from the coolant, but I thought these are made up stories. Flushing the coolant system was done, so anyways, any "radiator oils" should have been rinsed away...

 

Thanks for the photo. That is an oil cooler and it sounds like another of many parts the weren't available stateside.

I asked about the transmission fluid level because the transmission fluid circulates through the lower section of the radiator. That's how it is cooled. When the original radiator was removed, it had transmission fluid in it. That would mean the transmission fluid is low by the amount that was in the radiator - unless it was checked and topped off.

 

Thanks MarcusF, that's valuable piece of information. I should check that too. I read there was known problem with some Valeo radiators that used to leak oil into the coolant (or coolant into the trans oil was it), so that's a possible weak spot to watch for I presume. Current new radiator fitted is "Nissens". I'll update when I know what the problem was.

 

There are two radiators on my W208 CLK320, one is at the front to the bumper, and the other is to the engine's side - to the fan. Only the internal one, nearer to the fan was replaced - is this the one where the trans fluid is passing, and what's the function of the other (external) one then?

Thanks

 

The bad Valeo radiators only impacted some W209's. Even then, it wasn't long before the problem was identified and corrected.

The radiator like device in front of your radiator (front most) is the air conditioning condenser.

 

Geat stuff, MarcusF, thanks!

I've decided for now not to take the car to the dealer to check for the stuff in the coolant, on account of me not seeing any of that milk in it anymore. At least I don't see any of it when when the coolant is cool enough for safely opening its reservoir cap.

I presume that whatever it was - has been burned out OR it is only evident when the engine and coolant are still hot after driving, but not when they've cooled off.

Still, I'll keep an eye on it just in case..