Slow top, no leaks, no fault reports
 

My vario top has been ultra slow since the MB dealer topped up the hydraulic oil level in the pump months ago. Opening the trunk (in reverse) alone takes more than the 16 seconds the whole cycle is supposed to take. I’m not loosing oil. The front lock cylinder is clean, and so is the top of the roof liner. The pump occasionally times out but it gets the open or close cycle done eventually. Roll bar and easy pack are just as painstakingly slow.

I bought an Icarsoft MB V2.0 today and it reports
’313 solenoid valve and pump outputs OK - yes’.

I am sucking out hydraulic fluid from the pump in stages (emptying the reservoir) and topping up with the correct MB fluid. The ‘old’ fluid looks clear, unsoiled. No sludge comes from the bottom of the container.

What am I looking at? Could someone previously have used a different fluid, that is now a bad cocktail with the correct fill? Is there a cylinder that is constantly in open connection with the pump, that could be leaking internally, waisting pressure?

Tips would be appreciated!
I am new to the Icarsoft tool, obviously. Am I missing something there?

There are seals inside the cylinders that can leak internally, so no fluid spill int he trunk, but the hydraulics won't operate (or operate slowly).

In the Icarsoft scanner I did not find any data/testing of the individual cylinders. Can they be tested on board?

Top Hydraulics explained on this forum how to test, onboard, four cylinders for internal leaks. Halfway I decided to give up, as two bolts that need to be loosened for the test are obstructed by some hydraulic lines. While at it, I noticed that the lines 20 and 21 can be moved about (see 2 seconds video). No signs of leakage. Is this a problem?

Possible air in the system?

You bought a scanner (iCarsoft). It is utterlyy useless in this case. What you want is a diagnostic system; specifically, a Chinese-cloned Star Diagnosis System (SDS). What's the difference? The scanner will show you fault and sensor data and little more. SDS will do all of that, of course, but critically it also has software routines which automatically test some components and guided routines for manual testing most others.

Absolutely. All of the lock cylinders and I believe the tubular frame (trunk) lid are continuously pressurized when the pump runs. In conjunction with a test kit SDS has the ability to test each one for an internal leak. In your case you can manage by running the pump with specific hydraulic lines removed from the roof valve block. I explained the procedure here or on Benzworld about a year ago.

Another possibility is a weak hydraulic pump. To investigate that you need a special adapter from M-B and an hydraulic pressure gauge.

When I bought my SL500 in '06 the roof took about 23 seconds to complete a cycle. By '13 it took perhaps 90 seconds.

I checked the system with Star Diagnosis and a pressure gauge and found nothing out of specification, and so there was nothing to fix. Somehow for no apparent reason after a few years the top got faster, and now it might be 17 seconds to complete a cycle.

slow top function
 

For what it's worth a year or so back mine did the same slow deal after adding fluid. But after one or two cycles it went back to being normal. I'd just try cycling it. I personally felt it was air in lines. Be that as it may it did return to normal in a short time and still is working fine.

moretech

Thanks guys. I don’t think I’ll be that lucky re. air in the system. It’s been a long time and the roof has made many cycles. But it DID become slow all at once, after a top up with fluid. Taking the hoses of from the pump turned out to be a bridge too far, as I described in #3.
Finding someone with SDS seems the logical next step :(

I did not watch the video, but I suppose you may be able to loosen all but one of the retaining screws to facilitate access to the remaining screws. If not, I would expect that you can swivel the hoses out of the way to access any of the screws. Be mindful that a worker on the production line was able to tighten the screws, so you really should be able to loosen them.

Without a pressure gauge and the ($2000?) test kit SDS can not absolutely pinpoint a leaky cylinder. My advice is to remove the hydraulic lines as explained in my post from c. one year ago.

For those who are interested: bobterry’s post, mentioned by him, was written on July 30th, 2018. I could use that man in and around our house and garage for a while.

Bobterry questions if I may! In your earlier contribution you said:

”You can check for internal leakage with a simple test.

Have the roof closed and the trunk lid open. Use a screwdriver to close the latch on the trunk lid so that the roof controller does not recognize the trunk lid is open. Access the numbered hydraulic lines going to the roof pump and remove lines 30, 32, 33, and 34. Have someone activate the roof closed switch while you watch for fluid coming out of the disconnected lines and valve block. There should be very little or no fluid seen at all. Significant fluid from line 30 indicates a leaky front lock cylinder, 32 a leaky tubular frame cylinder, 33 a leaky left tubular frame lock, and 34 a leaky right tubular frame lock. Significant fluid from any of the exposed ports on the valve block suggest it is faulty.”

I have the trunk liner out, to allow the hydraulic lines for more play, disconnecting them is next. My understanding is that I remove the retaining plates, which exposes ALL the lines. Will they all pop out (#100 will be under pressure, I know)? Do I have to wrestle them out of the block, and later on, how skilled a job is reconnecting them to the block again? Should the retaining plates and the ports and lines be perfectly clean, free from oil?
I’m intimidated by the prospect of creating a mess...

My instructions fail to state that once the four hydraulic lines are removed the retaining plate should be re-installed prior to operating the roof control. This way #100 and the other lines will not pop out.

The four lines are easily removed and re-installed in the block.

I would expect there to be no hydraulic oil evident when you access the block. Yet if you do see oil, I wouldn't be concerned unless you suspect there is a significant leak. You do need to be concerned about keeping dirt and other contaminants out of the hydraulic system.

https://cimg6.ibsrv.net/gimg/www.mbw...54f94e4ee.jpeg
That was a very tough job. I tested the four lines and none of them leaked. That puts the suspicion on the pump and the valve block. Costly....

Can I install a new pump/valveblock just like that, or does it have to be coded into the system? Perhaps the risk the fault lies somewhere else melts away against the dealer tariff for diagnosing and curing my problem...

Nothing in the vario roof system is VIN coded.

The roof hydraulic system is an enigma to me. On two cars I have owned I have seen a system that checked out fine yet was horribly slow and then suddenly get very fast for no apparent reason at all. So it seems to me one could replace the pump/valve assembly and get no improvement. And if there is an improvement, I wouldn't be certain the old unit was bad.

For the years that my roof was very slow I had a SmartTOP module installed. That greatly eased the annoyance of the slow top, since I didn't have to hold the control switch and was free to assist the movement of the top.

Someone mentioned air in the system. Possibly that is the case and a certain set of circumstances must be in place to purge the air.

I did tilt the pump sideways and ran it, as suggested, but to no avail. If there's any other circumstance worth trying, I'd like to know.... The roof has been getting slower and slower.
Gents and ladies, I shall need your good thoughts and well wishing, because I just phoned the regional MB dealer to let them fix the probem. Don't want to get stuck with a stagnant roof during our summer holiday travels. Appt is early June, because their specialist is on holidays now (so there's still time for any surprise-me-solutions...).

I suppose you saw an old post that suggested an air bubble can form near the pump's intake port, and running the pump with it tilted can eliminate the bubble. According to M-B that bubble can cause slow, noisy operation.

You're taking one for the team, as I view it. I've been on a handful of these posts over the years, and no one has ever reported back what was the fix. I'm sure what you learn in June will be beneficial to many now and in the future (including myself).

I predict air is in the system, somehow.

YES! It happened! Today my roof suddenly started opening/closing as it should. Air bubble? Probably. I sure hope the snail episode is over. Just a week before the appointment at the dealer. Hosanna! :D

What would be considered significant fluid?

There should be no fluid coming from the cylinder return lines back to the pump reservoir. If I saw several drops, I wouldn't think the leak was having a material effect on the roof operation; but if I saw a spray, I would conclude it was the problem.

thebfirst time I tried this I did have some fluid come out. I tried again and no fluid came out. Could this be considered as working normally?

I don't have an opinion on that one way or another.

Yesterday afternoon I installed my rebuilt top lock cylinder done by cab-hydr. The speed fittings were a very convenient way of doing this.

I am planning to operate the top today. I am assuming there is a little air in the system, especially around the new cylinder. Is there anything I need to do to get the air out...some have said just "operate the top several times until the air is worked out of the system." Is there an air release valve on the pump I need to loosen, or does just "operating the top" do the job by itself?

Sorry, just not familiar with working with this system. Any suggestions appreciated. btw, 2009 SL550.
Thanks,
Reid C.

Using the top should purge any air out. There is no air release valve (except for topping up oil). Depending on the amount of air trapped in, your oil level might sag just a bit.

Yes that seems to have worked fine. Thanks!