What's going on?

[mrpatterson2008]

2016 movano 2.3td

Had headgasket failure symptoms.

New head gasket, head skimmed the full works £1600.

All was good then 1000 miles later the coolant was pressurised up and had risen a few inches in the expansion bottle. But no engine overheating.

Drove it another 700 miles like that then removed the egr cooler and pressure tested it. It was leaking. Replaced it for a new one and all was good again.

1000 miles later and I'm back to the system pressurising up 🤬

What's going on ? Where do I start ? 🤔

[Mr MXT]

Cracked block?

[E-bmw]

Or head.

Get a compression & leak down test done.

[InitialDave]

On some engines, if it warps the head, the force of it pulling against the bolts/studs as it does so can create a "pulled up" area of distorted metal around the bolt/stud holes in the block, which will interfere with the reassembled engine maintain a good HG seal.

[mrpatterson2008]

Thanks , I'll get the leak off test done and report back.

The head was skimmed when the new gasket was done and I was assured the block was very unlikely to have cracked.

What seemed so strange to me was how I can get 1000 miles before I see any symptoms.

Anyway I'll get the test done and see what it shows

[Smint]

Water pump not doing its job for a variety of reasons? i've seen impellers loose on shafts or corroded away.
Rest of cooling system up to scratch?

[GreenV8S]

Do a block test aka sniff test to see whether you're getting oil or combustion gasses in the coolant.

[DVandrews]

GreenV8S said:

Do a block test aka sniff test to see whether you're getting oil or combustion gasses in the coolant.

This 100% ^^^^^^^^^^