Next chapter in the saga of this roof. So far I have fixed the windscreen pillar pin which makes contact with the micro switch confirming that the roof is closed and I have fixed one of the flap mechanisms which was not signalling that the flaps were out.

Next issue was a dead PSE pump which had blown its fuse that told the roof system that the boot divider was not down. I have replaced the PSE pump motor, although I do have a vacuum leak somewhere. (On the list of things to do)

I can now get the roof pump to work. In down selection, the windows go down halfway, the rear deck lifts about three inches and the top latch unlocks. The pump sounds like it's stalling. It won't go any further. Have removed the rear deck assist strut. It's quite weak, so a new one is on order. But even with a helping hand, the rear deck won't go all the way up, nor will the operation progress any further. I suspect a hydraulic pressure issue.

The question is: Is it a weak pump or do I have an internal hydraulic leak? The hydraulic lines have been disconnected. Could there be an air lock? Is there a special bleeding procedure, or does it self bleed? The reservoir is at the correct level. It did go down after a few operations and I topped it up. The level is no longer going down and no evidence of leaks from any of the cylinders.

Any tips to help diagnose?

 

With top closed, just cycle your rollbar few times or as often as needed. Should go up or down reasonable smooth.
It will tell you if it has leakage, lack of pressure...etc.
System is self bleeding. Front windows half down, rear windows all the way down....before these conditions met, trunk deck will then raise all the way back.

 

Because in your case the pump stops, you might want to check both 118 switches on the tubular frame locks. When one sticks, shorted to ground, you land in your situation. The switches are in series, a failing cable insulation shorting current to ground tells the controller the lock(s) remain(s) closed.

 

I think 118 is working since rear deck raised about 3". Beside windows won't drop until 118 sequence is completed.

 

OK. I closed and locked the roof closed. The pump continuously runs, but the roof doesn't move very much in either direction. The top latch almost fully engages, but not quite. I gave it a helping hand with the Allen key. When it was fully up, I tried the rollover bar. The pump continues to run but it won't raise. The unlocking pistons almost work. I can see the springs on the rollover bar actuator moving in, but there's not enough oomph to raise the bar.

Definitely sounds like a hydraulic pressure issue. Weak pump maybe? Electrically it sounds fine. Are there any user serviceable parts inside to check? Seals or O-rings for example? Or could there be an internal leak across the valve block or a cylinder in the system?

Edit. I did double check the valve block manual release valve. It is screwed all the way in.

 

" valve block manual release valve" Do You refer to the pressure relief valve at the hyd. pump unit area where you manually turn it to relief pressure?
Sounds like low pressure problem.
My guess is that relief screw. Take it out and have a look. There is a O-ring at the end. Check the condition. You may also been tighten the screw too hard and crushed the screw end where it does the sealing. Good Luck.

 

Please let us know if you solve the problem. I have invested about $3-4k in the Vario roof. The roof worked perfectly after I replaced the front latch cylinder with a Top Hydraulics rebuild. I have had subsequent leaks, working periods, replaced all cylinders, had Top Hydraulics to rebuild the pump, replaced front latch assemblies, etc. After the roof last worked for a few cycles, after pump rebuild, the trunk became stuck pointing up with flaps deployed on the opening cycle.

 

If there is a leak - your pump will be low on hydraulic fluid. There isn't much of it in the system and it drops very quickly even if you have a small leak. Just check the level in the plastic container.

When you say a support strut, is it the one on the passenger side assisting the cylinder? Do you have a part number for it?

 

Meaning that the seals in some cylinder are bad, but the o ring may be good so the fluid goes around the seals and out the other supply line. thus not lowering the fluid level or leaking on the carpet. I am in the process of trying to find the culprit in my 2005 SL500. In the process I was going to change the seals in the lift assist cylinders on both sides but I can't figure out ow to take them apart. So I would appreciate any help anyone can give me with that and I will report my results here. I am going to try to add a picture here of the assist cylinder.

If anyone knows how to take this apart please let me know. Thanks, John Seal

 

I went through this. My car is twenty years old. The weakest seal leaks. I send it for rebuild to FL. I put it back, the system is pressurized. I wait for the next seal to leak. You cannot rebuild these at home. The endlink is pressure fitted. Takes special setup to take it off.

 

So here is an update. The roof still isn't operating correctly, although I have fixed a lot of problems that it had. Using my DAS I was able to fix all of the electrical problems. I had a bad flap microswitch and the plunger that operates the A pillar microswitch was broken. Then I had a leaking roll over bar pawl release lock cylinder. That was the reason I was slowly loosing fluid from the reservoir. I replaced it and now I no longer have any leaks. But operation was very slow and laboured, so I changed the pump with a brand new second hand pump.

It improved operation, but I still couldn't get it to complete the final closing of the boot deck at the end of the opening or closing sequence. I replaced the electronic control module with a brand new second hand one. No fix.

I then suspected an internal hydraulic leak from the deck operating cylinder, although it opened perfectly with plenty of force, it still wouldn't close without a helping hand. I replaced that one with a brand new second hand one. No fix.

Going back to my DAS, there is troubleshooting section that details that exact fault, but in order to do the test you need a hydraulic pressure gauge and fitting to go into the pump. I don't have that piece of kit and I guess not easy or cheap to obtain. Although it did say the one of the reasons for this fault could be an internally leaking lock cylinder.

So I ran the roof operation one more time and held the switch in the operating position for some time, even though the rear deck still wasn't going down. Then I touched the two lock cylinders. The left one was warm and the right one was cool. I think I may have found the problem. The left one may have an internal leak going past the seals causing friction and heat.

Anyway, just ordered a brand new second hand one off eBay.

I'll keep you posted!

 

Trunk lid drive cylinder (located at the left rear of the trunk) is the only cylinder that tilts & rotates the trunk lid. If your trunk won't rotates up or down, I would concentrate on this cylinder only.
Both left, right trunk frame lock cylinder are used for trunk lock only.

 

The two frame locks, front lock, and trunk lift cylinder are all on the same circuit. An internal bypass in any of them will reduce the pressure available to the others.

 

I always like to follow up on these forums. So often you read about people's issues and they never post if they've resolved it.

Well I'm happy to report that I now have a fully functioning roof. It's taken me the best part of a year to diagnose and repair all the issues it had. My guess is that the original fault caused all the subsequent faults that were introduced by all the other mechanics trying to have a go at fixing it. The fault was an internally leaking left hand side frame locking cylinder. The replacement actuator fixed it.

My next project is coil overs. It's currently a low rider ever since the front left strut exploded and dumped all its oil on my garage floor. I'm going for Silvers Neomax.

 

Thanks for posting the resolution. I payback the forum whenever I resolve an issue with the solution. After $4-5K I still have a roof stuck open. How did you determine you had an internal leak?

 

when it’s running (or trying to) touch the cylinders. If it gets warm it’s the fluid leaking past the internal seal causing friction and heat.

 

Thanks for the play by play. I'm having the same issues and going to start this morning with the diagnosis. If I find any other problems that may help I will let you know.

 

Anyone have any ideas on a roof pump relief valve not tightening. I think threads are stripped. Don't want to buy a new or secondhand pump for a simple but key function, not working.

 

I spent about $800 on a pump rebuild at top hydraulics. They replaced the relief valve with a straight blade screwdriver bolt or needle screw or whatever non OEM part. The top only worked for a few cycles. Then the roof stayed stuck mostly down. After replacing all cylinder seals myself or via top hydraulics' rebuilds, other mechanics work and about $5,000, it is still stuck down.

 

That is my experience as well. I had the pump rebuilt by them twice but they system still not working. Sort of gave up on this for now.

 

I think the only way to deal with this roof is to develop a troubleshooting tool that can open and close a cylinder at a time. I am thinking of adapting a manual hydraulic pump to these fitting, so you can apply pressure to individual cylinders and measure possible by-pass. The pump has two pressure rails and a loss of pressure on either will trigger a situation where some cylinders are operational and others are not.

 

Can someone tell me if there are pressure relief ports on the hydraulic motor that would open and "leak or spray" in a pressure overload situation? I have never had a pump problem until my left trunk lid actuator developed a major leak. I am thinking that the leak,causes the pump to run excessively, over pressurizing the other side causing a Pressure relief situation. Second does anyone know where I can learn about the hydraulic pump to potentially troubleshoot it? I have scoured the internet and found no info...just places that will repair it...

 

I don't think there any pressure relief valves in that system

 

There are two pressure regulating valves internal in the pump. One maintains pressure on line 100, the other regulates the main pressure line. They are in parallel, so either one stuck open would result in low pressure.

As far as internal bypass, it is an issue with one of the cylinders on the circuit that includes the frame locks, front lock, and the trunk lift cylinders. On this circuit, all of these cylinders have pressure on the rod side anytime the main pressure circuit (valve y1) is active. Note that this valve is open pretty much any time the pump is running. Even roll bar operation requires y1 to release the lack pawls. The lock pawls and load assist cylinders are single acting, so no real concerns with internal bypass. The main cylinders are not always energized, so you should get at least partly through an open or close cycle even with severe internal bypass in those. That leaves the roll bar cylinder, which is the other cylinder that can cause issues.

For the roll bar, a good cylinder should hold pressure on line 100. A bad piston seal will allow fluid to drain back to the return line and will not hold pressure. With the frame locks, front locks, and trunk lift cylinders, the best method seems to be to check for heating at each cylinder. I would expose all of the cylinders and then attempt to raise the roll bar. This will activate valves y1 and y2 and put pressure on the rod end of all four cylinders. If they have bad piston seals, fluid will be forced past the piston and generate heat. Good seals will not allow bypass, so there should not be any heating.

Another good approach is to just remove the four cylinders and have them rebuilt. All are very prone to failure with age and will need repair at some point anyway.

 

This is great explanation. Is there any documentations or diagram on the hydraulic circuit of this pump? I had these four cylinders rebuild and I do have great pressure on line 100 but they roof is still struggling to operate, which I believe is due to an internal bypass in one the rebuilt cylinders.