welding a w202

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maf155

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May 16, 2013
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74
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alfa 155
i will be welding a small patch on the floor of my 1999 c240.
so i will disconnect the battery, is there anything else that needs disconnecting to protect ecu/software ??
 
It's amazing how some w202's suffer with rust. Just really happy mine is still very solid, well i think so until my foot goes thru the floor. T.
 
Something often overlooked and at least as important as disconnecting stuff/plugging in surge protectors is placement of the return clamp- clipping it to something convenient as opposed to close to the weld and on the same panel/part being welded is asking for trouble as is not cleaning the contact point for the return clamp back to clean metal
 
Just gas weld it problem solved :thumb:
 
i will be welding a small patch on the floor of my 1999 c240.
so i will disconnect the battery, is there anything else that needs disconnecting to protect ecu/software ??

Whereabouts is the rust patch on the floor? as that is all that I thought I had, until my jacking point collapsed. It had been weakened by the rust patch in the floor, it was rusty as well but the floor rust had crept into the inner sill and the outer sill but this rust was under the factory rust proofing, do check under the your plastic sill cappings/side skirts at your outer sills, especially at the front and rear closing plates, and the jacking points, and use all four jacking points with the standard jack to ensure they still solid under load, and that the ramp/jack pads haven't sunk into the floor.
Take a look at this link, at the work I had to do on my AMG 202, please bear in mind there was no visual indication of just how bad this was, though I knew there was a rusty patch on the front passenger floor, it wasn't holed only rusty and the steel of the floor pan you could tell had got thin, so when I started having issues with the front passenger side jacking point I thought I would get the floor pan checked as well.
Be warned the pics of the rust in the link, that was uncovered is enough to make you cry, it did me
http://www.mbclub.co.uk/forums/mbclub-projects/135085-w202-rust-word-warning.html
Regarding your original question, because of where the rust was, they had to disconnect all the ECU's in the footwell and the main ECU box to move the looms and protect them from the heat, both connections of the battery was also disconnected.
 
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the rust is on the nearside front jacking point / sill / footwell. theres isnt a major amount but it is a bit awkward. i have now been through this car and can say i am pleasantly suprised how little rust there is. not many 13 year old cars dont need welding. but this is solid in the places i wanted it to be.

so where are the ecu `s ? i did find one of sorts in the pass footwell that was behind a square plate.
 
thanks andy i have looked at your thread .... its nowhere near as bad as that, but am mightily impressed with how yours was sorted.

just need to know where the ecus are...... and theres no way i can gas weld it lol.
 
The ECU's are behind the plate in the passenger side footwell, and under the bonnet on the passenger side just in front of the screen in the box with the diagnostic socket in.
Good luck
 
ta, i will be tackling this on weds, while checking this car i have pumped loads of dinatrol into it so hopefully it will stay in good condition for many years now.
 

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