Unexpected EGR pressure

[Rawze]

(03-19-2023 )Mrkentee Wrote:  ...
It’s demandated, and has a disc between exhaust manifold and EGR cooler, and is also blocked in the venturi tube. It’s not blocked between EGR cooler and flexible pipe. I just checked all that and there’s no leakage, or exhaust flow.
It it were intact, I wouldn’t expect too much moisture in the EGR, it should be dry.

you just stated your issue in this post... you have a dead circuit blocked off at both ends .. that cannot breathe, or relieve any pressure when it heats when the air inside it expands. That is why it had some pressure behind it.

- BTW: The pipe connection (in that photo) at the top of the EGR valve there is notorious for going bad, rusting out, etc. It also causes mysterious fuel mileage losses on CM871's that are NOT de-mandated. It also is a place that commonly collects moisture and condensation .. so it might not be your EGR cooler leaking at all that cause the eventual water buildup.

The EGR valve itself on CM871's sits in a low spot on the engine EGR piping and is subject to all sorts of condensation issues. On non-deleted trucks, it contributes towards its untimely demise, it rusting out, etc.