Any success stories regarding milling the head of a BHW engine?

Good day all:

For those B5.5 owners that might have/had a "warped" head: any success stories of being fixed via machining/milling? Approximate cost?

I presume that there might be cases in which the 'deformation' of the head is so slight that milling it by a skillful shop has a good chance of saving the engine for more years to come (assuming everything else is in good shape in the Passat).

I would like to stay on point on the above questions and not discuss the chances of this event happening in the first place. Thank you!

How warped is the head?

I do not know yet. Car is going through various kinds of diagnosis to rule out (or not) causes besides a warped head.

I was trying to get any response to my question to see, if in a worst case scenario (meaning head is warped but not severe), what to do:

1) Machine the head-> tricky and risky for what I have read so far

2) Look for a replacement head -> perhaps difficult to find one in good shape and not too far.

QuickTD said:

Test the EGR cooler first. I've never seen a warped BHW head, or even a bad head gasket, and I've been squeezing three of these very hard on stock bolts and gaskets.

Seen tons of bad EGR coolers. Did the car severely overheat?

Click to expand...

I believe my TDI specialist has been looking closely at the EGR area but no 'smoking gun yet'. No severe overheat under my watch. I bought the Passat used in early 2012 so before that I do not know. Carfax did not show anything related to an overheat scenario. But then you cannot trust Carfax for everything. Things can be hidden.

Besides this 'silly' coolant over-pressurization dilemma, the car is in a very good shape. I have done as much preventive maintenance as I could in all areas with dedicated TDI gurus in Texas! I would like very much to continue driving the Passat. It serves well the needs of my family. It is a safe car.

Our machine shop checks the straightness in two arenas: the actual mating surface that goes against the block, and the camshaft journal. BOTH need to be true. You can "clean up" the head surface, so long as the valve stack is also checked (with hydraulic lifters, there is a tiny bit of fudge factor there, but not much). But if the cam journal is not true, then they put the head in an oven and bake it for several hours to get it malleable, then, while still hot, take it out of the oven, place it on a fixture and put it in a press... push it true (checked with various instruments), then once trued up in the fixture in the press, it is allowed to cool down slowly in that position. This gets it back straighter and any final cleanup will be much less involved.


But remember, VAG heads are VERY chunky, they do not warp easily, and MLS head gaskets are not high failure items either. I have heard of, but never seen myself, BHW head gaskets failing. No idea if an overheat was involved or not. And I do not know the circumstances involved in the repair because I was not the one doing so.

Thanks Brian for the detailed information.

For the information I have gathered the location doing the detailed inspection of my Passat head (yes it is almost 99% chance of being removed to be sent there) has the full trust of my TDI specialist, so I feel better this way. After the detailed inspection there will be a decision to machine it or not. If YES then the cause of the coolant over-pressurization will be the head being not straight (warped). I wish for this option to get this over and fixed please!