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I am thinking of buying a 2006 STS but I am very leery and scared of the NorthStar engine. All I see is money flying out the window.  I have owned a 99 Deville Concourse, an 01 Deville, and as of yesterday an 05 Deville ALL BLOWN HEAD GASKETS! I have always had complete service at the dealer and oil change every 3000.   3 cars in a row? what are the odds? Is it the NorthStar engine that sucks,? OR the Deville because of the way the engine is mounted in the vehicle? Im at a loss,,,, should I even buy another Cadillac? Any advice would be most appreciated, especially with regard to the 2006 STS purchase.

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The RWD northstars have the engine in the proper orientation which perhaps helps heat transfer.  I have not heard head gasket issues with them.  The V6 was as popular at the time in the STS due to lower price but similar output, but has its own worry list


Bruce

2016 Cadillac ATS-V gray/black; 2013 Cadillac ATS 2L Turbo Premium (Wife's)

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1 hour ago, caddygeek said:

I am thinking of buying a 2006 STS but I am very leery and scared of the NorthStar engine. All I see is money flying out the window.  I have owned a 99 Deville Concourse, an 01 Deville, and as of yesterday an 05 Deville ALL BLOWN HEAD GASKETS! I have always had complete service at the dealer and oil change every 3000.   3 cars in a row? what are the odds? Is it the NorthStar engine that sucks,? OR the Deville because of the way the engine is mounted in the vehicle? Im at a loss,,,, should I even buy another Cadillac? Any advice would be most appreciated, especially with regard to the 2006 STS purchase.

1999 was a somewhat problematic year, there is a recall due to aluminum block material if I recall.  Now that does not mean that yours was in that group, but I wanted to mention that.

What mileage did your Northstars fail at?

I have a theory that detonation occurs at high rpm due to the air/fuel ratio leaning out.  Some will point to the knock sensor  which senses knock and retards the engine to stop detonation from low octane fuel and say I am wrong.  However, what concerns me is detonation from leaning out at high rpm because the fuel filter is partially clogged or the pump cant keep up with the demand. Add to that a low octane fuel when the engine calls for premium and the potential for detonation increases. At 5500 to 6200 rpm the knock sensor may kick in but too late to prevent huge combustion chamber spikes from detonation putting huge stresses on the head bolts, threads, etc.

My advice is to make sure the cooling system is perfect, temps are always good, premium is used when required and tier 1 fuels always, the fuel filter is changed often and fuel pressures are checked at WOT or an A/F gage is fitted.  Keep in mind that dyno operators and engine dyno techs will never run WOT, till they monitor A/F ratios carefully.  If your fuel filter can deliver sufficient fuel to 4,000 rpm but fail to keep up with delivery beyond that, it will starve the engine and produced destructive detonation.  The damage from detonation would be cumulative over time stretching headbolts into plastic zones, etc.  An engine with a crappy cooling system running hotter in the summer is a prime candidate. The fuel filter is often overlooked in these engines.  

Read this wonderful article written by an old friend of ours as to how damaging detonation is:

http://www.contactmagazine.com/Issue54/EngineBasics.html

 


Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Go look up 2003-2008 Toyota 2.4 L head bolts. Huge problem...typically the back 3 bolts (firewall side) pull up...Toyota has moved on. 

Those use the same M11 x 1.5 thread. Not that there is anything wrong with that....just the same. 

Your 2005 should be using a M11 x 2.0 thread. We do rent the Timesert kit for that. 

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