Head gasket replacement

[745 TurboGreasel]

Originally Posted by v8volvo

Technically that is the procedure, but if you already have a 2-notch gasket, that's what you should use and measurement is not necessary. The gaskets come in different thicknesses, the more notches the thicker, and the reason for checking piston protrusion is to see how thin of a gasket you can get away with -- you want the thinnest one the engine can take based on the out-of-deck measurement. However, D24T engines use either the 2-notch or the 3-notch from stock, so if you already have a 2-notch gasket, you know that you can use one of those and it's the one you'll want.

I disagree, here is why;

Originally Posted by v8volvo

The more serious trouble comes when you find someone who *is* willing to work on it and they only figure out after they've got your engine taken apart in their shop that they don't have the knowledge or equipment to get the job done.

then they put it together wrong to get it out the door.
Measuring protrusion allows you to determine if someone previously installed the wrong gasket. I've seen quite a few people do it, including VW on their $6500 reman engines.
It also lets you see if any rods have been bent in a bad headgasket or valve crash lockup event.