Leaking Hydraulic Hose in A207 E350d Cabriolet Roof

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Jun 8, 2020
E350d A207
It was really sunny in North Manchester this morning and I thought what the heck - I'll open up the roof and blast the heating on. It made a bit of a noise but didn't open - and on the third attempt I noticed a nice puddle of fluid on the passenger seat dripping down from the roof. It looks like hydraulic fluid to me as it isn't as greasy as oil and after a bit of internet searching I am pretty sure that the hose is leaking. I could find surprisingly little on the internet but according to the Car Wizard this is a common fault:

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and takes many hours to strip down and replace the hoses. (I had actually stumbled across this video several months ago).

On the US forums they talk about a company which sells a patented Hydraulic Hose Repair Coupler for this job

It's expensive for what it is - but is going to much a cheaper solution .

A couple of people on the US Forums say that they have used these and they work

I have spent a few hours phoning up garages (incl a Merc specialist), soft top repairers and hydraulic line repairers who all tell me that the line has to be totally replaced. None of them seemed keen on fitting any repair kit that I bought from the US - and even though it looks fairly simple to fit I would rather that somebody more capable than myself did it. Also it presumably is going to take a while to arrive and the car is dripping lots of fluid over the front seat (which despite actually is bringing up the black leather very nicely - so isn't going to make my wife happy as a new hair product.

Has anybody got any experience with this problem?
I've actually discovered the source of the leak and it is a cracked hose as I suspected.
The issue of using the repair coupler is what caused the break in the first place. Was it on a bend point and is putting a rigid coupler there a good idea as you will create a stress point either side of the coupling? Is it because of the whole pipe is deteriorating and needs a complete replacement as it may happen again.

If it is no to either of those then it looks like a practical solution.
All done.

Got the kit- fortunately HMRC didn't add the VAT - so with postage it was $132 - ridiculous for what it was but bargain of the century if it holds. Took 4 days to arrive from the USA, and was advertised as kit especially for E Class A207 cabriolets!!

Guy (well I presume "Cwcaruso" is a guy but maybe he could be a woman) on the US MBWorld.org forum kindly gave me some more instructions including a photo. Suggest that you look at this first.

All I will add to anybody doing this repair is that:

1. I initially couldn't get the top open. Lifting the lever unclipped the latches (squirting lots of fluid). Initially I couldn't manually open the top as it wouldn't fold back. But after I lifted the back tonneau / hood cover between boot and back seats up to fully vertical - it was easy to fold. Lifting the hood to half open gives good access - almost certainly necessary.

2. The clips securing the hoses seemed undamaged - but it looked like they had somehow opened. This had caused hose to crack on the hood fold and so leak badly. The other hose has a slight kink but looks like it is still okay. After finishing the job, I closed the clips up, added a couple of cable ties for good measure and have ordered some self amalgamating hose repair tape off eBay for £5 to wrap around to give a bit more protection if it will stick.

3. the fit between the couplers and the 12" of hose provided in the Cabriolet Hydraulics kit was tight. I suggest that you put the couplers on this first as you can do this on the workbench / kitchen table.

4. the couplers slipped very easy on the hoses already installed. Despite lots of claims that you wouldn't be able to slip these on and off - this wasn't the case. I tried to get the couplers positioned so that they were securely in the place where the hose doesn't bend and enough space that the hose can still slip through the clips.

5. The hood wouldn't close again when pushing the lever due to all the lost hydraulic fluid But it would fully open so allowing me access to the hydraulic reservoir is in the little hatch on the lhs of the boot. There is a little 13mm nut on the top allowing access (I would be careful not to drop it : ) )

6. It was practically empty - well below Min. I used my pipette for testing up antifreeze to fill it up (until it broke and had to buy a syringe). It is self bleeding and took 300ml to fill up. I used the Febi ZH-M. I am attaching the spec sheet.

7. Guess that I will need to check level after opening and closing it a few times. And to check the clips / cable routing.

8. Hydraulic fluid looks like it made my black seats come a treat - better than Simonz Leather Conditioner!!


  • Hydraulic fluids Specification 343.pdf
    65.1 KB · Views: 2
Just to say that the other house went a couple of weeks ago. So if you are replacing one and the other one is slightly damaged you are best of replacing both at the same time.
Cabriolet Hydraulics don't have any couplers in stock. So I tried:

a) buying 4mm OD coupler from a specialist shop in Manchester and a second hand hose from ebay for about £20. I thought that I might be able to sand down the hose to make it fit, but I had no joy. As soon as I got through the thin plastic sheet there is some sort of material.

b) bought 5x Brass Brake Pipe Connector Tube Tubing Joiner Line Union 33mmx10mm 3/16'' off ebay for £7. These were a complete disaster. Although they seemed to fit my spare bit of hose very nicely when I fitted them they completely started gushing hydraulic fluid and I struggled to manually close the roof. In my panic as it was about to rain, I didn't hook in the rollers in the back of the roof into the tonneau properly when I closed it.

To open the boot electronically you need both the latch at the front firmly closed with the allen key (I struggled to get this to close all the way as the allen key that I had was a bit short) and the roller clips in the back of the tonneau to be engaged.

Fortunately I was able to open the boot with the key.

There is a video about closing the roof manually on youtube everywhere such as
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but there is also a better one at
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which also covers manually opening it.

c) bought two couplers from Graham at Convertible Cabriolet Hydraulics Hose Repair Couplers at £60 each. His description is wrong - these are for the 4.5mm OD and are exactly the same as those from Cabriolet Hydraulics when they have them in stock.

When I put the car back together I couldn't get the knobs in the boot behind the lining to rotate. My problem was that I had already tightened the hydraulic pressure valve with the 6mm allen key first. Even then they were really hard to turn. You need to really pull them out. I cut the lining but it seems to have gone back (I have put a bit of tape behind it) and it barely notices. So personally I wouldn't bother with trying to remove the trim.

Then the top wouldn't close with the switch. There was a message briefly saying Top Operational, the windows went down and but there was not even a noise from the hydraulic pump. I figured that I would have a large bill from a specialist. But it turned out that a bit of fiddling with the knobs in the boot sorted it out. Mine when clipped in are not with the indentations at 12-6 o'clock - more like 11 -5 o'clock - but they have definitely clipped in.

As you can guess this has been a pain in the backside. But it is working.
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