EGR cooler residue

Anyone else have a white buildup inside the coolant passages of their EGR cooler?

I suspect it's dried up coolant from when it was removed from a high mileage car that wasn't flushed out with water. It comes out as a white, flaky, papery, film that will crumble to white powder. But it is adhered to the inlet/outlet inner walls pretty good.

In the picture showing the deeper view into the cooler, the residue is the darker gray color against the shiny silver surface of the stainless steel.

I tried rinsing/soaking it with hot, almost boiling water, after plugging the inlets/outlets. That rinsed out some, then I poured some white vinegar (mild acid) in and let it sit for a bit, then followed up with hot water flushes. I still see it coating the deeper surfaces.

Followed up the rinses with a heat gun on low setting to try and dry it out. The hot air current is blowing out bits of this stuff out, I guess as the water dries out and releases the stuff that's been loosened.

Should I be concerned about this, or will the little bit of this residue not be a problem when I put in new coolant after the EGR cooler swap?

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That would be my guess as well, or whatever remains after SLLC coolant dries.

I'm probably over thinking this. The inner surfaces of the entire cooling system in my car is probably coated in some kind of slimy coolant residue by now anyway.

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I'm sure I could just get a big disposable aluminum baking or roasting pan and boil the entire EGR cooler in a water bath on my propane turkey fryer.

Whatever the residue is, it should get softened and dissolve in water, the universal solvent.

It's a good thing that the EGR cooler is made out of pretty robust stuff, namely stainless steel.

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OK, good to know it's common, and probably nothing to be concerned about.

I'll just leave it.

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Both coolant and exhaust flow through the EGR cooler, in separate circuits.

Similar to an air to liquid intercooler on turbocharged vehicles.

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The EGR cooler is stainless steel, I'm sure of it, because I've put in HD degeaser, drain cleaner, Oxy-Clean, and near boiling water. Sometimes plugged on one end and soaked for days with straight drain cleaner.

Through it all, no rust or damage, except for the nuts welded on the very end of the cooler, which have a light coating of rust now.

However, while I was using my handy, indispensable magnetic pick-up tool to keep nuts and gaskets from falling down while trying to reach around hoses to grab them, I noticed that the EGR cooler body is strongly attracted to the magnet.

I always thought that stainless steel was non-ferrous and didn't attract magnets. It must have iron in it but get its stainless quality from other high level metals like nickel and chromium.

Found this information on the web:

Magnetic Properties of 304 & 316 Stainless Steel



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I wonder if a wire could be pushed through a spiralized cooler though, that is the most effective way I've found to loosen crud built up in the cooler.

 

I'm not worried about the coolant side of the EGR cooler anymore, since its been stated that it is common and nothing to worry about.

I'm referring to the inside, exhaust exposed cooling fins and tubes. I would think that a straight through design like the OEM one is easier to clean than a "spiralized design".

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