Bobertsawesome

So about 3 weeks ago my car started to get low on coolant. Out of the blue and nothing had happened beforehand. There was no smoke from the exhaust, and no coolant smell, and an oil analysis when changing the oil showed 0 PPM of coolant in the oil.

This left my head scratching, the oil levels stayed consistent over a few coolant top-ups so I knew it wasn't getting into the oil pan. I feared it would be a bad head gasket or simply the seals on the coolant lines going to the turbo. I bought UV dye to try and find where it was coming from as I was starting to get pretty worried. I've had it in the system for about 5 days now and still couldn't find a trace.

The problem? The windshield washer. Used the washer coming back on the highway last night. Pop the hood to check for a leak today and low and behold... all around the washer tank cap was UV green fluid. Apparently, there's a coolant line that runs through the washer reservoir to prevent the fluid from freezing. Who would've guessed

MDMercedesGuy

I’m not surprised, but only because I’ve been around Mercedes for years and always found this to be an elegant if not slightly ridiculous solution for warming the washer fluid.

At least it didn’t fail internally, leaving you to slick your windshield with coolant every time you hit the washer. I’ve been down that road before.

Bobertsawesome

Haha, unfortunately, it did fail internally. So I'm going down the rabbit hole in WIS to get the instructions. I was wondering why my windshield washer was leaving behind a slightly opaque film on the windshield. Solved 2 problems at once I guess

Bobertsawesome

Completed this repair about a month ago but never did update the post. In case you don't have access to WIS/ARSA, here are the instructions.

Start with attached document AR82.35-P-6000ME Remove_install washer fluid reservoir of windshield washer system. That's the main document. When removing the washer system pumps (AR82.35-P-6002ME), you don't need to disconnect the fluid lines or electrical; simply lift the whole pump module vertically to pull it out of the reservoir and leave them dangling from the hoses/cables to the side out of the way. I highly suggest ordering 2 new rubber grommets (Part# 001-998-73-01) that go into the reservoir and maintain the seal for the pump connection. I didn't foresee this, and mine were a little caddy wumpus. I didn't have time to wait, so I just boiled them to "rejuvenate" the rubber and reused them. Took me about 2 hours, the fender lining is a pain.

Tools/parts needed:

• Washer reservoir heat exchanger (167-830-10-00): part suppliers seem not to stock this and it comes from the main MB warehouse special order, ~2 week delay.
• Washer pump rubber grommet (001-998-73-01)
• Fluid line clamp (HF has them or just get them off Amazon): needed to keep coolant from spilling everywhere.