How much rust is too much for a W115? - Mercedes-Benz Forum

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post #1 of 4 (permalink) Old 04-02-2015, 03:50 PM Thread Starter
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How much rust is too much for a W115?

Thinking of buying this car a few states over. Bringing to a mechanic for a pre-purchase inspection but the seller did mention the drivers side floor board has become soft in a couple spots. He also made me aware that was easily fixable. If there was no other rust on the body could a few soft spots be easily popped out and fixed? Checking the car out tomorrow. It was a southern car and apparently it has "minimal rust". I know rust is a 4 letter dirty word. Is even a little rust right off the bat a sign to run away. Plan on putting a few thousand into it right off the bat.

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post #2 of 4 (permalink) Old 04-02-2015, 10:06 PM
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A few small spots in non critical areas wouldn't be so bad, but you would have to take out the seats, carpeting and battery to really see how bad may be. Take a long handled examination mirror and look at the under side of the doors, the sill plates, underneath the battery. Also, at least lift up the front floor mats and look for rust there.

Something you may not have considered when deciding for a w115 is changing the oil filter. They change from underneath the car. Read a few threads on changing an oil filter here vs read a few on the W123 forum to see the difference. It can get to be a drag and is more difficult on the W114/W115
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post #3 of 4 (permalink) Old 04-03-2015, 08:52 PM
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There is no such animal as minimal rust on the /8. If there is rust, there is a bunch of it. Trunk is going to be a rust haven, so might need a new floor welded in. Quarter panels also harbor rust if they are not kept clean and dry. Cabin will have severe rust in all four corners. Just the way the water flows for some reason. I am getting ready to weld up my corners on the 300D. Prior owner… some way back, thought fiberglass and snot would solve the issue. It does not. The front tires spit water and gunk back on the splash guards, and muck takes up residence behind them. The 220D had steel panels, but those rotted out, so MB changed to plastic. The muck still grows between the fender and the floorboards, soaking wet and eating away at the metal. This makes the front jack points fail. Carpeting is a wonderful sponge and holds water agains the metal for months on end.

The reason there is water intrusion, is that the window seals are shot. Rain water will flow to the cracks in the seal and then into the footwells as well as the trunk. MB did not use galvanized sheet metal until the late 1980's, so when you do fix it, use galvanized.

Best solution to cabin rust is to source all new sheet metal floor and have a body shop install it. That will cost twice the value of the car, but increases its value by $300. Any rusty metal needs to be ground down to clean metal and holed parts cut out. Weld in fresh metal. I am using old computer cases for my donor material. I guy I know uses old microwave oven cases. It is about the same gauge.


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post #4 of 4 (permalink) Old 04-04-2015, 08:23 AM
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Recommend against welding galvanized metal. It produces a toxic gas when welded. You can also get sheets of metal from Lowes, home depot, etc. You can indeed grind downrust to bare metal but any Barr stuff needs to be treated. Go to Eastwood for com for a range of good products and prime it all with etching primer. Repairs aren't tough but they can be time consuming ... take a look at the "mission of mercy" thread from the beginning to get an idea of what rust repair looks like and how much time it can take.
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