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I seem to be getting quite a bit of condensation inside the car after it has been raining.
Are there any obvious areas to check?
i have cleared the drain holes under the scuttle,
near the wiper blades already. They were filled with mud incidentally.
The trunk does get a little damp and I’m not sure how to check the sunroof drains. I can’t see any obvious damp inside the car and the carpets are dry.
So, I did some digging today. It has been raining on and off for a few days.
I found damp in two areas.
1. In the right hand side rear passenger footwell. I am in the UK so that is the same side as the driver. I park the car on a mild incline, so it could be coming through the driver footwell and running back. I hadn’t considered the incline so never really checked properly. I am going to park the car facing downwards for a week to see what happens.
2. In the trunk. I did some dismantling and it looks like water is running down the rubber trunk seal (on the inside) and then pooling at the lower lip, where it eventually gets into the trunk. It’s a bit strange, because I don’t see how water gets into the seal. It may be that the whole area needs to be stripped and cleaned because it isn’t draining properly. Right rear passenger footwell View from inside the trunk. Water appears to be dripping from the striker area. Tiny bit of surface rust on the left side.
I suspect whatever is causing (1) is the cause of the condensation on the screen.
To this, make sure your A/C drain is clear & the Water from the evaporator isn't backing up into the cabin.
and the incline is probably simple enough to check - park the car in the reverse direction.
Or user garden hose & check gaskets out.
To this, make sure your A/C drain is clear & the Water from the evaporator isn't backing up into the cabin.
and the incline is probably simple enough to check - park the car in the reverse direction.
Or user garden hose & check gaskets out.
How do I check the AC drain? Is there a guide anywhere?
1. Water in the rear right passenger footwell
I checked all of the drains today. All three of the pipes under the hood are clear, as is the fourth 'non pipe' drain route on the driver side. The two sunroof drains that I could see are clear as well.
Question: Are there more than two drains for the sunroof? I found it odd that I could only see two drains at the front. If the front of the car is raised relative to the rear, as was the case with my car, where does the water go?
At this stage I am thinking that the cause of the damp is either (a) AC evaporator drain dripping into the cabin or (b) the sunroof.
Suggested next steps? I'm really not clear how the evaporator drain works and/or how I might test it.
2. (Small amount of) Water in the trunk
I stripped the trunk seals back today. First removing the rubber, then the two black trim pieces either side and the big trim piece along the bottom. I found some light surface rust under the lip of the trunk, nothing major, but I did find also two small spots where the metal lip had rusted through, right at the top. The rubber seal also had evidence of water in it. The black trim piece on the right side was also broken at the bottom but that I am sure is not the cause.
I think that what is happening is that water is getting into the inside of the rubber seal (where the lip has rusted through) and then running inside the seal and along the lip, before dripping out into the trunk at the bottom. That would make sense from where I am seeing the water. If that is the case, I'm really not sure how to repair the lip without welding. There isn't ever much water, just a very light pooling in the trunk after heavy rain. I don't think this is linked to the condensation on the screen.
1. Water in the rear right passenger footwell
I dried this out and it hasn't come back. Speaking to my wife we suspect that at some point over the preceding week a bottle of water was spilt. That would make sense, a massive amount of water appearing from nowhere and then not returning. I have been pulling up the rear mats and checking, but so far, nothing.
2. (Small amount of) Water in the trunk
As in the post above, I found that the upper lip for the trunk had rusted through. Just a little, and enough for water to run along the inside of the rubber seal and to the bottom. On inspection, I found that the rubber seal had actually started to open up as a result of the rust.
I removed the seal, stripped the trunk liner down and had a small section of new metal welded in. The other light spots of surface rust were cleaned up, treated with Bilt Hamber Hydrate 80, primed with a zinc primer, painted and lacquered. I then refited everything with a new rubber seal and new fixings. The result appears to be water tight, with no more leaks into the trunk. A good result! I noticed after refitting that, when parked on a slope, water pools at the top of the trunk lip. I think that was the original cause.
One thing to look out for W209 guys, I will be parking as close to level as possible.
3. Condensation inside the car
I had a local shop do the welding and then I refitted everything myself in my garage. So far, I haven't seen much more condensation, but it has only been a few days. If I am lucky, the water in the footwell was a spill and that, perhaps coupled with the water in the trunk, was the cause of the condensation. The only other places are AC drains and rear sunroof drains (if they exist, I'm really not sure how to access or clear them).
As a final point, I was looking again at the drains under the windshield and was reminded that one of the pipes wasn’t fully connected (270 in the attached). I had always assumed that this was normal (it was directly under the drain, just not connected) but checked a few pictures online and realised that it needed to be firmly connected. I removed the battery and refitted the pipe. Easy. This was for a right hand drive car, so the pipe was on the same side as the battery and, crucially, the cabin air intake.
With all the work done, the car is now almost bone dry, even after heavy rain. I’m going to call that a win.
EDIT: Update for the benefit of others. I eventually found that my car was leaking in a number of different places.
- The windshield drain in the diagram
above not being connected and drains blocked with leaves / debris
- The trunk, solved with a new trunk seal, new side trunk trim covers and press studs (with silicone around the seals). Before replacing the rubber I actually had to do some welding to the upper lip. Issue was water running inside the rubber seal. I also replaced the foam seal for the tail lights, although I don’t think that was an issue.
- Sunroof leak. This appears to be a manufacturing issue common to lots of cars of this era. The sunroof cassette was not properly sealed at the front. The only solution to that is to either remove and refit the whole sunroof (massive job) or simply park the car level. If pointing the car downwards this can actually be quite bad. Recall / TSB somewhere, but reading it won’t really help!
Thread ressurection, but thanks to the OP and for anyone else with a leak in the passenger footwell connecting pipe 270 firmly to the scuttle tray in the diagram (next to the battery) did the trick on my 2004 CLK 320 (RHD). The pipe had not been put back fully after having the windscreen replaced. There is a YouTube video showing the problem pipe more clearly here (LHD car)
Thread ressurection, but thanks to the OP and for anyone else with a leak in the passenger footwell connecting pipe 270 firmly to the scuttle tray in the diagram (next to the battery) did the trick on my 2004 CLK 320 (RHD). The pipe had not been put back fully after having the windscreen replaced. There is a YouTube video showing the problem pipe more clearly here (LHD car) https://youtu.be/vC3v9gTj-XI
Glad that it helped.
In the end I replaced the grommet for the hood release cable as well. Done by a shop, not sure if just the grommet or the whole cable.
I've read about that leaking grommet too - on my list of things to check as likley to go next if it hasn't already! In addition there is a rubber blanking grommet in each front wheel arch (remove the rear part of the wheel arch liner, and its located towards the bottom of the bulkhead where it meets the side skirt). Both of mine had perished and split, and are in the area where water drains out through the fender. The MB part number for these is 110 987 0544, but I just used a 32mm blind grommet from an electrical shop and it fitted perfectly (see the cream grommet in the picture).
Not sure if it was actively allowing water in, but happier now it is sealed. These CLKs seem to be slightly leaky beasts as they get older! Replaced cream grommet below (original black)
There is also a big issue with the seal around the sunroof on many of these cars. With my car facing downwards on a slope, water will leak through the internal light dome and into the car. No issue parking the other way. The headliner will be wet if that is an issue.
Its a big job and people appear to have mixed results, so I have left mine.
I've read about that leaking grommet too - on my list of things to check as likley to go next if it hasn't already! In addition there is a rubber blanking grommet in each front wheel arch (remove the rear part of the wheel arch liner, and its located towards the bottom of the bulkhead where it meets the side skirt). Both of mine had perished and split, and are in the area where water drains out through the fender. The MB part number for these is 110 987 0544, but I just used a 32mm blind grommet from an electrical shop and it fitted perfectly (see the cream grommet in the picture).
Not sure if it was actively allowing water in, but happier now it is sealed. These CLKs seem to be slightly leaky beasts as they get older! Replaced cream grommet below (original black)
10-09-2020, 06:27 PM
