2015 w unclogged egr pipe at 115K miles

As far as I've seen, evidence is scant that the EGR system's deficiencies cause engine overheating. Clogging of EGR, especially if unequal between cylinders, might, just maybe, cause momentarily abnormal cylinder pressure that overstresses the head gasket.

I'd put more money on thermal gradients and thermal cycling, though, as the culprits.

 

If seem some say that the 2015 gasket was improved and less susceptible to leaking. Any truth to that?

 

Head gasket? There was a revision to the head gasket, but not sure it was during any 3rd gen production years.

my opinion is that it’s the EGR system’s clogging overtaxing the head gasket, but that’s just me.

 

Redesigned pistons, and stronger/wider rings were done mid 2014 and up.
And there was an upgrade to the head gasket.

People who drive more highway miles go longer before it fails. I went 301,000 miles before mine started
to fail.

If the egr circuit gets clogged, like the cooler does, there is excess back pressure in the exhaust circuit
which causes more pressure in the cylinders and more stress on the head gasket.

If you know what to look for, you can catch it early and won't need to have the head machined....

 

The back pressure that you see at the exhaust manifold is based on the amount of exhaust gas flow out of the engine cylinders. At engine idle (low RPM), the back pressure will be low. Maximum back pressure will occur at maximum engine RPM.

How much flow do you think goes through the small EGR valve versus the flow that goes through the exhaust system and out the tail pipe? Opening or closing the EGR valve will have very little effect on the back pressure in the exhaust manifold.

FYI, the EGR valve is only open during mid throttle. The EGR valve is completely closed at engine idle and at full throttle.

The pressure in the cylinders is based on the design of the engine. An engine designed for a 12:1 compression ratio will have a higher cylinder pressure versus an engine designed with a 9:1 compression ratio.