Rear wash/wipe

[catgate]

My newly aquired C250TD Est. naturally has rear w/w. However, the 'wipe only' behaves in a way that, to me, seems less than satisfactory. When switched on it will complete a wipe of about 110 degrees, and then pause for a few seconds (I have not counted how many). It then restarts its travel and completes the 180 dgrees and does an additional reverse 180 degrees, back to its starting off point. After a few more seconds starts the cycle again and continues this way until the button is pushed to stop it. Now it is certainly intermittant, "But not as we know it Jim." I presume it should do 180 degrees per sweep. Can anyone, please, shed any light into this black hole?

 

[Anders]

I suspect the reason it doesn't complete the 180 degrees swipe is due to either a seized mechanism or too much resistance. I would try to remove the interior trim to have a better look at it, but it should do the correct 180 degrees each time...

 

[jimmy]

When first switched on it should do several full sweeps and then go into intermittent mode. It should also come on if you select reverse with the front wiper on, cool!

As anders said, it sounds like you have a problem with the mechanism, suspect the pivot or gears are very stiff or very loose.

 

[catgate]

Thanks chaps, I shall have a poke about now that I know what it should do.

 

[catgate]

Having read your words of wisdom I attacked the beast this morning, and removed the wiper motor and co. onto the bench. Unfortunately I found nothing, because I could not get the cover off the top of the 'gearbox', because the 'star' socket screw heads were not compatable with my set of star screw drivers (they fall between sizes 10 and 15, are they a MB special?). However, the spindle feels quite free and there appears not to be any backlash. This then led me to wonder about the means/mechanism of controling the timing and length of the sweeps. Is it done by means of contacts within the gearbox (i.e. on the big gear wheel) or is it done by the heating up of a bimetalic strip, or a combination of both, or, then again, possibly neither? Is this knowledge in "the public domain" anywhere?

jimmy
When first switched on it should do several full sweeps and then go into intermittent mode. It should also come on if you select reverse with the front wiper on, cool!

Bearing in mind that we are talking about an Aug '98 (R reg) vehicle does this still hold? Because, if it does, the mystery deepens still further, since it seems to want to do nothing other than a faulty intermittant wipe.

 

[fuzzer]

If its the torx screws with the raised bump in the middle of the head then try this ...

http://www.maplin.co.uk/products/module.asp?CartID=040609132343347&moduleno=11520&Products=1

 

[jimmy]

I don not think the wiper motor rotates one way, stops and reverses. The wiper action will be the motor running continuosly one way and the mechanism makes it sweep back and forth not electronically.

Mine is an early 98 and it has the intermittent feature.

 

[catgate]

fuzzer

If its the torx screws with the raised bump in the middle of the head then try this ...

http://www.maplin.co.uk/products/mo...1520&Products=1
__________________
Regards

Thanks, but unfortunately they seem to be "convensional"

jimmy
I don not think the wiper motor rotates one way, stops and reverses. The wiper action will be the motor running continuosly one way and the mechanism makes it sweep back and forth not electronically.

That is a very elegant notion, something akin to the front, you think. One thing that puzzles me about this problem is that the sweeping motion stops for a little while at the end of each half cycle. This must mean that the current is switched off for a period and that period must be timed. Now my problem look as though the timing is out of sync. If I could find out how this timing is achieved, and how the switching on and off is done, I feel I may be halfway to a cure.

On a very much related matter has anyone any knowledge of the items for sale under

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&category=57254&item=4193643419&rd=1&ssPageName=WDVW

 

[fuzzer]

Thanks, but unfortunately they seem to be "convensional"

Have you got a pickie of the screw head and ill try and find a bit to take it out?

 

[catgate]

fuzzer
Have you got a pickie of the screw head and ill try and find a bit to take it out?

Thats right honourable gentlemanly of you. Unfortunately, once more, I am still working with a steam operated Olympus, and by the time pictures are prepared the whole mess could well have rusted into oblivion! One thing I did find out after I had refitted the thing, and just before I refitted the trim (I am gifted with afterthought), was that a small allen key fitted and turned the screw. I think, should I get more info on the setup and its opereation, that is what I shall use. After all it is driving on six faces/points and the torque must be minimal.

 

[catgate]

The following
http://cgi.ebay.co.uk/ws/eBayISAPI....ssPageName=WDVW
that I mentioned above supplied a two CD comprehensive "manual" for all the Mercs sold into the American market. A lot of interesting information, but none of it answers my question as to how the intermittant operation of the rear w/w is achieved.

 

[racall]

There is a complete wiper motor for sale on the german ebay site #7905123742. Slightly OT have you checked for rust round the boot handle? My advice is when you have the back panel off get some waxoil and spray it all over the inside of the tail gate.There is a post called (3 or 6) on this forum which is well worth reading.