Dealing with Stripped Head Bolts on a Northstar Engine

Published: 02nd June 2010
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If you own a Cadillac STS engine Deville 97 with a 32 valve 4.6L Northstar Engine that has a blown engine, a pressure and spark plug test will usually reveal that you have blown a head gasket. This occurs because of the stripped head bolts common in early models of the Northstar Engines. To fix it, you have to figure what bank it's on and get it replaced.

Unfortunately, it's expensive to get a Northstar Engine with a blown head gasket fixed. The task is complicated and time-draining to do it on your own. Stripped head bolts on a Northstar Engine are rather common from the models that came out in 1997, 1998, and 1999.

After this time, GM finally figured out how to resolve the issue, although some critics argue that it actually took GM a full ten years before they fully resolved the issue. The majority of issues, however, have declined since 2000, and it is usually the models between 1997 to 1999 that were most affected.

What happened in the earlier models is that the coolant was switched from a green-silica base to Dex Cool. When this new coolant was not perfectly maintained, the steel head bolts were stripped because of the metallic reaction to the soft aluminum block.

It remains a mystery why GM made a decision to move away from the block hardening process that was standard in 1997. Automotive experts estimate that the head bolts begin to strip around the 90,000 to 100,000 mile mark.

Unfortunately, even if you are an expert mechanic or have access to a reliable one, you can't simply use some hand tools and get the job done for a few hundred dollars. Instead, the entire engine block has to be removed, drilled and retapped. Then timeserts have to be installed. Once the head gasket is blown, it is usually necessary to get a new gasket rather than fix the gasket. Another factor to consider is the expert use of cam timing to get the job done well. This means that the work costs thousands. Given that the earlier models are only worth about $6,000 today, it means that the repairs can come close to the cost of the car itself. It can take up to 40 hours or more to get all this done and it can cost an average of $4,000.

The problem of stripped bolts in the block is a nightmare...not only for the car owner, who has to shell out the big bucks, but also for the mechanic involved in repairing the damage. Many less experienced mechanics have botched up the repair process completely.

About: It is not an easy job to have a head gasket replacement on a Northstar Engine. Thus, rather than getting the problem fixed a better solution is to simply swap out the engines for a used engine with reinforced head bolts. It costs a lot to get it fixed properly and it's difficult to find an expert at it, so the better solution is to get a used engine.

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