2000 Mercedes E300 Diesel oil pan crack

A crack should always be stop drilled if at all feasable to help prevent it from growing longer. An intricate shape that’s carrying approx 40 stationary lbs of oil that’ll be sloshing around in concert with heat and cool cycles, you bet this is a stressed component.
The one used Mercedes oil pan I saw had been smashed on a steeply humped rail crossing by a careless/reckless owner. The walls were fairly thick and that one looked to be a magnesium alloy.
What the damage looks like, whether it’s been dented or otherwise not perfectly flat and how close it is to corners will affect what kind of repairs may be possible.
One thing is for sure the area needs to be cleaned thoroughly. To do that the crack needs to be opened up. Grind, scrape to make a vee channel out of the length of the crack without making the crack any wider at the base. As for chips the pan holds lots of them during the normal course of operation and most of them are removed by the oil filter and draining the oil. Next spray a carb, MAF, electric contact cleaner that evaporates readily and if you don’t have compressed air go to a computer store and get a can or two of dust remover and blow into the crevasse you’ve created as you spray the cleaner, watch your eyes. Next comes the JB and some luck. I’d also consider fabricating a shield of sorts. Good Luck.

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This car already has a massive plastic belly pan . . . unless it’s been lost or destroyed

WOW, in that case that was some piece of gravel. Probably traveling at earth orbit escape velocities.

My 04 Golf had something similar, one piece with a scattered dozen ‘torx’ head screws which made DIY oil changes a time consuming pain in the ass.

To patch the pan in situ with out oil weeping out, I would drain the oil, then put a couple of quarts of kerosene in the engine and then drain them. Residual kerosene should weep through the crack pretty quickly, leaving a dry field. Maybe a little brake cleaner sprayed from the outside as a followup.

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Thanks for the detailed instruction, I am still waiting to try the jb weld, as the flex seal tape has been holding up relatively well. When I get some time and get it back to my shade tree, I will definitely do the JB Weld. Do you also recommend the “high heat” JB Weld, or the “Water Resistant?”

As stated previously:

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Thanks, I only ask because the “WaterWeld” states that it is specifically resistant to oil and “HighHeat” does not.

I’d go with high heat.

Edward Michalowski