The thing is, this is a different mechanic than the usual one I go to, and his garage is a very well known garage.. I asked him a second time whether it will rust or no, and he said it won't rust. He threw me into confusion by saying first that it will rust and then he said it wouldn't. I don't know if he said it wouldn't just to shut me up tho..

 

Kajtek1 is exactly correct. Corrosion can happen with those metals, but rust no. The corrosion is possible when these metals are no longer covered in fluid and become exposed to air. I wouldn’t worry about it.

 

That would be case for different forum.

 

If telling you that your aluminum heater core will rust is what gets you to fix it instead of bypassing it like some redneck hooptie, then yes. It's going to rust and the rest of the car is going to turn to iron oxide dust within minutes.

PLEASE FIX YOUR CAR PROPERLY or sell it to someone who will. If you can't afford to replace the heater core, how did you afford the Mercedes in the first place? What are you going to do the first time it throws a check engine light at you? Drive around with the dash lit up like an Xmas tree, 25 mph in limp home mode, but hey! I've got a Mercedes!

Sorry to go off the deep end here but as someone who buys old project cars ( and not simple ones either, V12 Jags, etc) the level of neglect on old luxury cars that just tanks their resale is insane. People just want that badge on the hood and that's it. It costs me pennies to fix some of this simple stuff that people just don't even bother with. Do it right. Your car isn't even all that old and already you're sending it to the junkyard. If you had to sell it now, you wouldn't even be able to find a buyer without a functional heater. The car is effectively worth nothing. Penny-wise and pound-foolish.

 

Rust?, the only reason I would think he has said that is because he used a metal pipe or copper pipe to bypass or no coolant to fill it.

If he used a aluminium pipe or plastic its no different than the heater core and will last no problem, sounds like you have back yard mechanics where you are, I would ask what type of pipe he used to bypass, if he says anything but plastic or aluminium, ask him why he used a pipe that would corrode over one that would not cause a problem and get him to do it properly.

 

I've been listing to you guys while you're trying to talk Saud out of committing Barr's suicide, but, in the process, I think you've answered all my questions. My 2013 E350-4Matic (144K) has suddenly started blowing anti-freeze mist through the AC vents, onto the windshield and it's noxious enough to gag a maggot! Needless to say I've stopped driving it. The only thing that gives me pause is that I'm getting no leaking of any kind in the car. Simultaneous to this debacle, I started getting engine oil in my coolant reservoir (but not coolant in my oil). At first I thought it was a blown head gasket, but through this forum I learned that the engine oil cooler presents those exact symptoms. So, just today, my mechanic finished ventilating my wallet for $985 to do the oil cooler, thermostat, coolant flushes and oil changes. I've already bought the heater core, but he doesn't have time to do it for a few weeks and I've got plenty of other iron to drive. The question is: Is there anything else that will present these symptoms sans the leaking into the cabin before we perform the exorcism on the heater core? I can't think of anything else, but I'd sure like you guys to prove me WRONG!!! Thanks!!

 

The only way coolant can enter the cabin thru the vents is the heater core. Put some UV dye in the coolant, run it for a bit. Find an endoscope and look into the heater box for a "glow" party.

 

Thanks Partner! This is one of those times when I hate being "right"!!!

 

Your engine oil, pressured itself through the oil cooler and next thing it blew out your heater core... I thought the cap of the expansion tank or the plastic tank seams supposed to vent pressure.

Have you ever found your engine dipstick popped up for no apparent reason or oil traces in VVT harness ?