Thanks to the forum....a/c drain hose (w/pix)

[Jeremy5848]

Thanks to all of you who have discussed the climate control system's drain hose from the a/c evaporator to the transmichigan hump, I didn't panic when I found the left rear passenger's footwell to be a swamp. Yes, I cursed this irritating problem, but to know the reason for something, especially 700 miles from home, is immensely reassuring. It changes the situation from a frustrating puzzle to the engineer's reason for being, "I get to fix something new!"

Apparently the foam hose (why did Mercedes choose such a thing?) in my 1985 300D's system had disintegrated some time ago but I never noticed because the car had never been in a warm, humid climate in the year+ I've owned it. Last week visiting Portland, Oregon was different. It was 85F and 70% RH and I ran the a/c constantly. The humidity, frozen out of the air by the a/c, dropped out the drain, leaked through the remnants of the drain hose, ran down the tunnel, through the driver's footwell and into the rear passenger side where it accumulated.

By the time I noticed, the footwell had a quart of water in it. Unfortunately, I had brought along some of my Mercedes manuals and two of them got fairly wet. Fortunately, I was able to dry them out and they seem to have suffered no permanent ill effects beyond some curly pages.

I took the mat, carpet, and pad out of that footwell and kept it empty for the remainder of the trip, sponging out the footwell every few hours as we traveled. To see me wringing out a sponge in the rest stop parking lot, people must have thought I had spilled something.

When we got home, I pulled all of the floor mats. Both front mats were a little wet, the right rear was dry. I put the car in the sun with a big fan and the floor dried out in a couple of days. The mats went into the sun and they seem to have dried out too. I was lucky to catch the problem before any rust appeared.

Replacing the hose was easy in theory, since I knew what and where to look. The actual doing was a PITA, because of the location of the drain. Removing the drain wasn't too bad. Once I had it on the bench and could see what it looked like, I decided to use a short piece of pipe insulation as a replacement. Even though the foam will disintegrate and I'll have to do the job again in another ten years, it was easier to install than other materials.

Removing the console would have made access easier but not very much so I didn't do it. The best way would be to remove the transmission and stick the hose up from below. You should not be surprised that I chose not to do it that way. I used a cable tie to secure the foam in place. I won't know if it works until I get into damp weather again although I suppose I could pour some water into the system.

The W123 also has one rubber drain hose on the right side near the Freon lines; it leads into the engine bay and was undamaged.

The pictures show what the old and new drains look like. If my hands were any bigger I would never have been able to do this job.

Thanks again to this forum and its great members for information that is in no book I've ever seen.

Jeremy

[JimmyL]

Now that is darn near the perfect post. Very well explained with excellent pics. Very very nice job!!

[Palangi]

Yes, good writeup.

That is a common problem, but I don't think anyone has posted pictures before.

[JimmyL]

Originally Posted by Palangi

Yes, good writeup.

That is a common problem, but I don't think anyone has posted pictures before.

Well, somebody has, but it was no where near the quality of the above.....

I've sprung a leak, evaporator drain hose...

gee that was a long time ago.....

[bodyart27]

Mine DIY was for a 126 if anybody needs one:

W126 Where is this water coming from!?!?

pics of repair on post #14

[dmorrison]

When replacing the evaporator in the 300TD and 240D I used a dishwasher to garbage disposal drain fitting from Home Depot. Its a firm rubber piece that I doubt will ever wear out. I cut it after figuring out the length required and then clamped it.

Dave

[hangit]

I didn't have time to run to Home Depot like DMorrison, so I cut a short length of bicycle inner tube and zip tied it to the spout. This should last a good long while, I hope!

John

[blindwolf]

Thanks for the heads up! I am going to check on mine in the morning, having to use the a/c for nime months out of the year here. I am sure that drain care should be on my scheduled maint. program. Excellent pictorial.
____________________
blindwolf
83 300D

The dishwasher hose was a good idea....I liked that. I used a 5/8 heater hose when mine fell apart. They are a bit thick and sort of a pain to get in place but once in they have performed flawlessly......very cheap to buy and will last the lifetime of the vehicle. I imaging a 5/8 garden hose would work also and probably more flexible than the heater hose.

[Shawn D.]

Originally Posted by dmorrison

When replacing the evaporator in the 300TD and 240D I used a dishwasher to garbage disposal drain fitting from Home Depot. Its a firm rubber piece that I doubt will ever wear out. I cut it after figuring out the length required and then clamped it.

The rotted/infested foam tube and its temporary towel replacement weren't cutting it in my '84 300td, so based on the endorsement above, I got an InSinkErator DWC-00 Dishwasher Connector Kit from Lowe's and installed it this morning.

I installed it by flattening it and shoving it underneath the case drain and into the hole in the trans tunnel, at about a 45 degree angle from the driver's side. Then I shoved a large screwdriver in the flattened open end so that the end was about halfway under the case drain, then used a hooked coat hanger from the passenger side to pull the lip out and over the other side. I then went back and forth from the driver's side to the passenger side, incrementally shoving the end up onto the case drain, using the large screwdriver and a prying/twisting action against the trans tunnel. Unfortunately, when I looked at it from the engine compartment, I saw the end was up against the transmission, so I had to take it out, cut off about 1/2" from the "outside" end and reinstall it. The rubber took all the abuse without so much as a gouge.

In the end, it fits snugly onto the case drain without the need for a clamp and also snugly fills the hole in the trans tunnel so there are no air leaks around the tube. It's also flexible enough that it accommodates the significant misalignment between the case drain and the hole in the trans tunnel, which is about 30 degrees and 1/2 of the case drain diameter off.

BTW, I suggest taking a few swipes at the bottom of the HVAC case with some 100-grit sandpaper. There were a few mold/sprue marks that gave me a few paper-cut-like cuts/scratches.

Thanks, Dave!

[Bio300TDTdriver]

After finding a nice puddle under my carpet on the driver's side I searched and found this thread. It has been 95 here and I have used the A/C more in the last 3 days then I did the previous couple of years. Pacific northwest vs Boston area.

The 124 isn't much different than the 123 when it comes the condensate drain failure. The repair is the same as well.

Once I removed the carpet bolster I took off the old tube which was really just a piece of wire after 26 years. As you can see from the back of the bolster it had been leaking for quite some time. It was only wet at the bottom, but the stain was far larger than the wet area.

I was able to use a piece of xps insulation to make a template for measurement purposes. The ID measured just over 3/4" so I bought 3/4" and 7/8" tubing. I ended up using the 3/4", but I had to heat it up in a cup of water to get the end to slide over the hard plastic end.

I cut 6" of tubing and forced it down through the hole. I then pulled it back up and forced it over the plastic barb at the end of the plastic tube. The plastic retainer that kept the old foam tube in place was too small for the plastic tubing so I used a pipe clamp on it.

I'm hoping the floor and foam pad will dry by tomorrow morning.

















The passenger side had failed as well.