Why does this Cylinder Head have cross bores to the head studs

[awemawson]

Just been steam cleaning a huge Dorman 6LE diesel of 1972 vintage, and much to my surprise found that each head stud had a cross bore parallel to the head gasket exposing a bit of the stud a little way up.

I suppose if you had a seized stud you could drill through the hole cutting the stud, pull the head, and have enough sticking up to weld a lever to, but maybe there is some much more subtle reason for it that you can tell me ?

 

[Spark plug]

Before you could say for sure, you need to know if the bore goes any ware behind the head stud.

But I like the idea, of drilling through the stud

 

[wristpin]

Way, way back it was not unusual to have coolant seepage up the studs causing corrosion and making it almost impossible to remove the head. I had a Daimler Conquest running with all the head stud nuts backed off and the head didn’t budge. Could those cross drillings be observation holes to give early warning of seepage or even for adding penetrating oil???
I remember reading in Car Mechanics magazine that at one time one could obtain thin tubular cutters to clear down between the studs and the head to overcome that exact problem. If a set of those was to come up in an autojumble it’s doubtful that the seller would know what they were.

 

[colnerov]

Hi, I agree with wristpin, it's for early indication of head gasket failure just like they used to put seepage or drain holes on water pumps.

Colin