JJ98SL500

I recently purchased my 1st 98 SL500. I have a lot of little things to repair since the car has not run in a few years....but the car only has 23k miles so I'll have a nice car when I'm done. I do have both tops. After manually removing the hard top (pump did not operate) I rebuilt the pump and got the roll bar to operate properly and then found out the soft top would only raise about 1/3 of the way up. The pump just switches off, same place every time. With the soft top seated all the way, the top switch will close and latch the cover. So that's where I'm at.... (Also I have windows working properly)
Thanks for any and all Help !!!! Jon

Top Hydraulics

Jon,

I have a few questions, and would appreciate answers to all of them for me to help most efficiently:

1) What was wrong with the hydraulic pump?
2) What do you mean by "1/3 up"? Where exactly in the cycle does the top stop?
3) What do you mean by "With the soft top seated all the way, the top switch will close and latch the cover."? Are you referring to the tonneau cover closing when the soft top is all the way in the storage compartment?
4) Do the windows drop about 1/2" when you open the doors?

Klaus

www.tophydraulicsinc.com

JJ98SL500

Thanks for the HELP !!! 1) the trunk had a water leak ... So the pump was sitting half submerged... I disassembled the pump assembly as far as possible, cleaned, flushed the motor and cleaned the motor some more ...and in a couple of days ..LOL ..works great !
2)& 3) Starting in the top down postion, activating the the top switch to roof up postion, the cover opens and roof lifts straight up ( I'm guessing this is the top main rams) then the pump shuts off. So by your diagram I'm thinking the bow extensions are the point where the tops becomes inactive. After the pump stops the top will then slowly (from no pump pressure) lower down, but not enough to activate the top down/up position switch in the drivers side storage compartment . I just push the top down .. About a 1/2 inch enough to engage the switch then I off /on ignition switch , pull back the top switch and cover closes, locks and pump shuts off.
4) The Windows do lower 1/2 inch when I open the doors and when I activate the top down switch the windows will lower completely up the up position .
THANKs Again, awesome info !!!!

Top Hydraulics

JJ98SL500, thanks for the detailed response - that narrows it down a lot. I will make some comments inline in blue.

Again, test the micro switch on the left bow extension cylinder, and let us know what you find. The pic below shows more detail about that micro switch assembly - it's taken from another thread that deals with repairing a bent one.


Klaus

www.tophydraulicsinc.com
http://www.tophydraulicsinc.com/en/c...y-instructions

JJ98SL500

Awesome Info !! I will check it out tomorrow and let you know ... !! I talked with the previous owner today .. He told me he thought the front lock cylinders leaked .. But I've not made it that far yet ! the cylinders that do work look relatively dry .. This car was left outside for a the last couple of years .... I got a lot of cleaning and service to do !!!.. My fluid level has changed very little since I have got the pump back in action ... I'm sure there will be a FEW cylinders that will need rebuilding .. So glad Top Hydraulics will be doing IT !!!

JJ98SL500

Continued....

JJ98SL500

Ok here's where I'm at .. If I manually close the top and start from there.... Activate the top switch the everything works proper till after the front latches... Then the rear half of roof will not lower ... The storage compartment is closed and locked ... The mirco switch is working , it triggers on/off at right before the highest point. I checked switch for continuity. The Hydraulics are drawing the back half of roof forward instead of pushing back to lower it down, the best I can figure the step from top up and latched in front to rear half closing is my problem. Besides a few
leaky cylinders (not bad at all, but will need new seals at least) Thanks , Jon

Top Hydraulics

JJ98SL500,

this is a rare combination of symptoms. It would be useful to know whether the previous owner has tried to replace or work on any cylinders before, to narrow it down, or you might end up having to check hydraulic line connections and solenoid functions.

Since you are mechanically inclined, I will let you jump into this a little deeper without having the dealer read codes first.

You may want to check out the micro switches on the front locks 1298000774 and 1298000874. When removing the windshield header panel, please be careful not to disturb the magnetic sensor in the middle - disconnect it before removing the windshield header completely. See page 3 of http://www.tophydraulicsinc.com/R129...%20Removal.pdf.

A part of your symptoms match the sensor having a short in it (or a sensor wire touching ground), and a part of your symptoms match one of the front lock micro switches not giving the correct signal.

The magnetic proximity sensor above the windshield is p/n A 129 821 14 51. It is used only in model years '95 and younger ('94 and younger in Europe). It is a Reed switch, which detects the proximity of a magnet. The magnet is in the front of the soft top. It can be sensed only from a close distance. Even if the sensor is not exactly in its housing, it will not get enough field strength from the magnet to detect it. Conversely, if that sensor is always giving a closed signal, then the top will not raise past the half-way point, because it seems illogical to the controller that there is a CLOSED signal when the top is not past the half-way point yet (approximate half-way point determined by the micro switch on the left bow extension cylinder).

Below is a description of how the micro switches on the front locks operate:







Please let us know what you find.

Klaus

www.tophydraulicsinc.com

JJ98SL500

Well good and bad news.... The good news ... The mirco switches are both good and so is the top sensor .. I checked the reed switch with a magnet. The passenger side latch was slightly bent ( not a very good mechanic has been in the front top assembly ) and mirco switch out of adjustment. I cleaned and adjusted latches to your specs ( Awesome Instructions ). Now bad news ... The pump starting shutting off after a second or two when trying to open ( pump is working perfect when operating roll bar ) so I don't believe it's a Pump issue. A switch is kicking it off is my guess. Before I could do much testing of the front latch's one of the latch hydraulic cylinders started leaking from the line connection...bad, guess sitting up and outside killed the seal. The cylinders have 09/08 DF hand engraved on them ? They have been out before because I had to repair a cross threaded bolt in the latch. So I will be sending you the front cylinders to fix. Guess the story will end here till repairs made. What is the correct adjustment on the bow cylinder ? And does the compartment latch have a mirco switch? ( I'm not where I can look at the car right now.. Just wondering ) ... I will FIX this ....with your HELP !! LOL... it is kicking my butt right but I refuse to go down !!

Top Hydraulics

The reason for this could be as simple as the trim panel with the magnetic sensor/Reed switch in it not being re-installed. The top will not unlock in the front if the Reed switch in a '95+ is not giving the "closed" signal, which it will only give if installed correctly, connected, and the top's magnet is nearby.

This is a very familiar story. 09/08 DF hand engraved onto the cylinders means that DF has "rebuilt" at least the front lock cylinders 1298001672 in 2008. While "DF" used rod seals that are comparable to Mercedes' OEM seals (outside of some flaws that we notice from time to time), he did not change the piston seals or the important port seals. Please note that the distributor p/n 1298000022 in the middle between the front latch cylinders also has six port seals. See http://www.tophydraulicsinc.com/en/r...indshield.html. It is advisable to have us upgrade it at the same time as the front lock cylinders - especially since the port seals on your cylinders are already leaking!

There are four kinds of seals in all R129 hydraulic cylinders, and Top Hydraulics upgrades them all:

1) Rod seals. These are the ones that seal the piston rod from the rest of the cylinder. When they fail, you will see fluid coming out next to the shaft (rod). These are usually the first seals to fail in the cylinders.

2) Cap seals. These are just o-rings that seal the top cap of the cylinder from the housing. They are usually the last seals to fail.

3) Piston seals. They seal the input and output sections from each other, as the piston slides through the cylinder. The piston seals have been made of different materials and sizes even in the same p/n cylinder throughout the year. Failing piston seals will cause internal leaks, which result in a pressure drop in your hydraulic system. Early model years have the added problem that the piston seals swell up and make it very hard to move the piston inside the cylinder. Crumbling piston seals can block valves or pinholes inside the hydraulic system, and it can be difficult to diagnose a piston seal failure without testing several cylinders once you find that your top is moving slowly or not at all.

4) Port seals. They seal the hydraulic lines where they are pushed into the cylinders. Port seal failure is becoming more and more common as the R129s age. They have a special shape that makes them seal under pressure. O-rings wouldn't do the trick. They are secured by precisely machined brass rings (accuracy about 1/100 mm). DIY removal of the brass rings will almost certainly destroy the brass rings.

Relax - we will get there. I have literally answered thousands of R129 owners' technical questions about top malfunctions before, and we can get your top working together. The best way is to approach it systematically at this point. Let's take care of the front latches and sensors, and take it from there, step by step.

Klaus

www.tophydraulicsinc.com