Do EGR coolers fail internally?

Has anyone heard of an EGR cooler failing and allowing coolant into the combustion chamber? Or vice verse allowing exhaust gas into the coolant system?
I’m tracing down a coolant pressure situation. Only two things I can think of are head gasket and egr cooler. This failure is common on ford diesels. They have notoriously had problems with head gasket failure and it took years to figure out that it wasn’t the head gasket as the root cause it was the egr cooler failing due to overheating because of low coolant flow because of plugged oil cooler upstream. The actual cause was crappy coolant that plugged oil cooler, ultimately leading to blown head gasket.

You must be talking about 6l Powerstroke as newer Powerstrokes are excelent engines.
The 6 l had a number of weak points.
The EGR AND oil coolers had small coolant passages, while engine with factory coolant was producing some stuff that would clog the passage.
Once 1 of those coolers start clogging, small flow would boil the coolant and blow it via system cap.
Add dummy gauge who will not show overheating for a minute or so and when that happens on uphill drive, it has to overheat the engine with known consequences.
The engine had only 4 head bolts per cylinder and heads were not strong regardless.
The "bulletproof" aftermarket EGR cooler had bigger pipes for coolant flow, while bulletproof oil cooler had to be moved from engine valley (nightmare to replace like on OM642) and cost quite few $$$

Well, I’m actually talking about that possibility in a Mercedes engine actually. But yes, that’s the issue I’m referencing. Can the Mercedes EGR cooler fail and allow coolant/exhaust gasses to mix.

You almost have it right, however it wasn’t causing the engine to overheat, it caused the egr cooler to overheat which caused small cracks in the coolant tubes. This allowed tiny drops of water to enter combustion via egr, and tiny drops of water when vaporized will grow to much higher volume of gas, and this spiked the Cyl pressures causing head gasket to blow. Most people blame the lack of head bolts or international engineers but those guys knew how strong those areas needed to be, and with testing they proved them to be sufficient. They just chose wrong coolant that had a short service life and the problem cascaded down.
Now, I’m not suspecting that exact problem surfacing in a Mercedes, but my knowledge of that issue led me to ask about the robustness of this cooler because it’s dealing with hot corrosive gasses and if it leaks for whatever reason the same thing can happen.

When on weak design anything can happen and maybe the mechanical failures of the coolers happen as well, it still was clogging that created most of the issue.
With better technology coming over the years, every 6l owner would drive with scanner displaying delta between coolant and oil temperatures. That would allow to catch troubles before they would become disaster.
EGR bulletproof cooler was like $300 item and easy to replace.
You can see in upper corner how aftermarket put bigger tubings inside EGR cooler.
https://www.fordiesels.com/ford-6-0l-tube-design-egr-cooler-2004-2010-egr500/
Those coolers are made with stainless steel and never heard about corrosion being an issue.

Absolutely, I've seen a couple fail on the 642 engines where they leaked coolant internally and caused a coolant loss issue with no external leaks and the occasional puff of white smoke from the exhaust.

Possible but not common in sprinter

The EGR cooler is a common weak point in the VW Crafter (Sprinters brother), loss of coolant, and no visible leaks. I'm suffering from this at the moment, and whilst the symptoms given indicate to a head gasket failure, a pressure test shows EGR cooler.

http://www.remmington.info/crafter coolant.html

The pressure test is on the egr cooler itself? I’m having coolant pressure problems but they remain after engine is left overnight so this made me think head gasket vs egr cooler but that is not really backed by anything other than hunch. So I guess I should separate egr cooler and cap both ends and apply pressure to test?

Gabe Athouse said:

The pressure test is on the egr cooler itself? I’m having coolant pressure problems but they remain after engine is left overnight so this made me think head gasket vs egr cooler but that is not really backed by anything other than hunch. So I guess I should separate egr cooler and cap both ends and apply pressure to test?

Click to expand...

Disconnect the cooler, adding a straight pipe in its place then test to see if you lose anymore coolant.

Mickyfin said:

The EGR cooler is a common weak point in the VW Crafter (Sprinters brother)

http://www.remmington.info/crafter coolant.html

Click to expand...

Does that have a VW engine or MB? Read a more recent article where VW’s putting in their own motors



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To answer the question !!
Yes they do.
I haven't seen one "yet" on a Sprinter van but with an MB 903 series its quite prevalent.
Hmm --900---- 900!!!
I bet you are all thinking what does that fit into??
Answer
Freightliner medium duty trucks--Freightliner labor hauler based bus chassis which scud about picking kids up for school--yes school buses.
Marketed by Detroit diesel a subsidiary of Daimler AG.

Still curious about medium duty MB engines? Then watch this and see what a bigger MB engine and its EGR cooler looks like.,
We have fixed hoards of these.
Dennis

https://www.youtube.com/watch?v=dZ5wbHmg8yk

May sound weird but I had this same symptom on my 06 Freightliner. Vanishing coolant, widely fluctuating temp gauge. Problem was ultimately the oil cooler gasket. (Engine finally decided to fill radiator with oil). Replaced gasket was easy. Cleaning the mess with repeated flushing over two weeks not so fun. BUT van is back to it's old self: no coolant loss and engine holds at 190F here in Mississippi. Hope that helps.

A quick answer for this if it has any significance with regards to OM642 Sprinters is "yes" & seen on three cooler units this year.

Essentially the internal matrix will leak and then furr up causing a restricted flow on the back side of the unit, confirmed if you remove the rear end cover .

This then causes a huge build up of carbon forming a surface patch restricting flow.

I asked my back office staff to identify how many formed an incidence factor.

Turns out we do on average over 5 years, 1635 SPRINTER repair/service incidents per annum and three units were found to be repaired with internal leakage problem related failures in 2019.
So I'll you folks can work out the number crunch extrapolation of incidence percentages if you are inclined to do so.
But yes they do leak. (well in 2019 they did!)
Dennis