Convertible top motor is dead

[poloplayer]

Hi ppl, seems like many of you have a great deal of useful technical knowledge to spare. I have owned a 1990 300SL (129 UK delivery 12 valve ) for the past five years. For the most part it has given me a great deal of pleasure until my convertible roof started acting up last year. First all the hydraulic seals on the rams gave way, which after a great deal of difficulty i managed to replace through a long drawn out DIY repair, it's amazing how cheap it can be compared with buying brand new rams.

Yesterday, after a couple of months of using the hardtop i decided to use the softop again, and to my dismay, the hood struggled to climb out of its compartment and stopped midway several times without completely closing, before finally stopping for good on about the 10th attempt. The Rollover bar does not move either now when i try to actuate it.

I have since closed the roof manually, and the warning light is off. When i try to use the convertible top switch the light comes on, but all that happens is some clicking noises of solenoids in the back, but the pump doesnt seem to actuate to move anything. Hydraulic oil level in reservoir is adequate, and there are no leaks. Fuses are all OK as well.

Any suggestions? My local mechanic has suggested that its now probably not really the electronic controller at fault as the solenoids work, so they reckon the pump motor has packed up. Any ideas where i can get it repaired or an economical replacement. Any ideas on how to test to be sure that it is indeedthe motor which is dead.

Not sure if this is related, but last week prior to this, my dashboard was lit up like christmas lights apparently due to bad earthing somewhere in one of the door sensors, but is now fixed after a local electrician sorted it out.

[bobterry99]

I am afraid this reply, isn't going to be of much help, but I do have a couple of thoughts.

You mentioned that when you tried to close the top, it stopped midway. If the controller did not sense that the windows were lowered at the point (maybe due to a faulty switch), then the motion would stop approximately midway with the forward part of the folding top pointing vertical.

But the slow motion of the top rising out of its storage compartment can only be explained by low hydraulic pressure. It could be that the pump is weak, but it could also be that the hydraulic cylinders you rebuilt have developed an internal leak which is causing pressure to be low. I believe the only way to really tell is to test the hydraulic pressure with a gauge which only your dealer probably has.

[poloplayer]

Thanks bobterry,

Since then i have managed to check things out in more detail and found thet the electric motor had burned out (tested it by direct 12V supply to motor terminal wires), at this stage i believe everything else is still working.

Have just got the motor rewound, will be installing it today..fingers crossed that all works well.

[poloplayer]

Great news, after reinstalling the rewound electric motor and cleaning up the pump and hydraulic tank for good measure, the softop works like a dream. Looks like it will give the new owner years of good use. Just sold the 300 SL....very sadly.