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Northstar Headbolt Repair by Ian

Well, even though this repair turned out to be a fairly big waste of time, .... I did take some pictures as promised. I'll start with a view of the (what I call) powertrain module sitting on a bench under the car. At this point in the repair, the right (rear) cylinder head has been removed and I've rotated the entire assembly 180 degrees so that I could work on it in better lighting conditions. These newer Cadillac's are quite amazing in their design of the powertrain module. It took me about 1 hr and 20 minutes to get this assembly out of the vehicle and onto the repair bench.  Nice!!!



Here is a closer look at the patient being prepped for timesert installation.



Closer look at the alignment plate, bushing and
alignment shaft (top left corner of the plate).
This is to align the tools properly over the head
bolt hole in the block.

Here is a picture of the tool kit that is used
to install the time-serts. My names for the parts may not be exactly correct, but you get the picture.

[Bruce notes: website: www.timesert.com ; Although some readers have successfully used time serts, the advice I get is "don't try this at home".  It is definitely a repair best left to professionals, like Ian for example].
  

A picture of a new Northstar head bolt. You can plainly see the different compounds that are used on the threads and under the head of the bolts as Bill has described them. 

[Bruce notes: the coating is applied at the factory, and cannot be repaired or reapplied in the field.  Northstar head bolts CANNOT be re-used, and new head gaskets must be used as well.]

Anyway, that was fun. Hopefully some of you will enjoy looking at a Northstar in various stages of repair. Next chapter will be the always controversial comparison pictures of the Northstar v-8 case halves and the Olds v-6 case halves. Maybe we can discover why the Northstar case halves leak and the Olds 3.5 case halves
don't!!! (grin)

Ian

[Bruce notes: my conclusion:  if you are having any head bolts off for any reason, the threads should be time-serted. period.]