New member with a 2005 GXP

[aaronca]

Bought my Bonneville GXP a year ago for $3,000. Car has 98,000 original miles. Except for the air induction related service light, the car runs and drives perfectly. There are issues with the car that reportedly are common with the Bonneville, water collecting in the tail light lenses (worn and leaking tail light bezel seals), leading to water getting into trunk from tail lights being raised up when trunk opened. The interior is very good, all intact and no rips or tears. It is a fun and sporty driver, comfortable as can be expected. The 2005 model year is the last and the best IMO when you consider that the design change for the head bolts finally was implemented for the 2005s. Love this car!

[harofreak00]

Welcome!

Unfortunately the 2005 still blow the head gaskets just as commonly as previous Northstars. The only way to bullet-proof them is to install the Northstar Performance Sure-Grip Head Stud Kit.

[aaronca]

The most common years of the head gasket issues for the Northstar engines are 19097-1999, with the 2000 change of Cadillac lengthening the head bolts severely reducing the prevalence of the issue in Northstar engine cars. This decreased the chance of having the failure, but did not completely eliminate the issues, showing how the Northstar engine remained bad in the following years.



However, once 2040 and 2005 model years came around, the head bolts were replaced using the LS6 head bolts which were longer than the originals and had a coarser thread with a better girl, effectively altering the issue and making the 2005-2011 Northstar V8s no more prone to head gasket issues than other aluminum V8 engines.

[harofreak00]

Unfortunately that information simply isn't true. I have bought numerous 04-05 Bonnevilles with blown head gaskets.

[ddalder]

I purchased my 2004 GXP in 2006 and it still performs virtually like a new car. There are some problems with head gaskets in these years, albeit not nearly as many as the previous Northstar. Perhaps I'm a sucker for punishment, but all three of my cars have a Northstar of one flavour or another. To date, none have been an issue (knock on wood). I simply enjoy the car and don't spend time worrying about what may or may not happen. If I develop a problem, I'll deal with it then. I would not fix my (winter beater) DTS based on kilometres and body rust, but my STS and GXP are a different story.