[BeelzeBob]

So.. What does it take to rebuild one of these things? One of the things I used to worry about on my ETC was the engine going.. I mean.. Isn't is like $8000.00 to replace the engine? So, are there any rebuild options? What would something like that involve?

 

[BeelzeBob]

A new Northstar engine costs what - $8000.00 plus installation?

 

[BeelzeBob]

From what I recall, the origional weren't graphite, but another composite that did not distribute heat as evenly as graphite and thus caused warping, they also contained steel rings. Since the HGs in the 95-98s were insufficently torqued (there's a GM service bulliten regarding the main bolt repair and new torquing procedure that puts more clamping force on the heads) coolant or even moisture from the air could seep in and corrode the steel rings, causing gapping or depending on the location and sevarity of the corrosion, gasket failure.

I am currently looking into possibly replacing my N* if the source of my rough idle on cold start and Hydrocarbons in the coolant are coming from a leaking HG. It could be a number of other things but I will be calling Jasper Engines soon to find out exactly what the difference in the HG is and who manufactures them.

Northstar headgaskets have always been compacted graphite gaskets...with stainless steel firerings and a stainless steel expanded metal core.

95-98 engines did NOT have "insufficiently torqued" head gaskets. The GM field service bulletine changed the bolt tensioning specs slightly FOR SERVICE. That had no effect on the bolt tensioning done in the engine plant originally when the engine was built. Just the service spec was modified, not the spec used in production.

There is really no difference in the head gasket material, construction, quality or supplier after all these years. Basically, the OEM gasket is the best compacted graphite gasket obtainable. Period.

 

[BeelzeBob]

Bbob, can you tell me what the new torque specs are? Are these applicable to all year Northstars? I checked Helms website and the Service manuals are not for sale for 98 Devilles or 95. Where else can I get Factory manuals? Thanks for all your help and efforts that you put into this site. I for one have learned a lot of useful information from you and others. Keep up the good work! :thumbsup:

Tighten the bolts in sequence 30 nm + 60 degrees, then on a second pass give them an additional 60 degrees, then on a final pass an additional 60 degrees. That will work fine. There are several different tensioning specs but they basically do the same thing. With the new gaskets and new bolts and fresh timeserts the 30 nm + 60 + 60 + 60 will be fine.