: What causes a headgasket failure?

02-16-12, 11:46 AM
Just curious as to how the headgasket fails on all the Northstars. So far, my 97 ETC with 127,047 miles has run fine since last December 2011 when I purchased her (with a few electrical problems). I'm going to. Change te oil in December (unless I go on a summer road trip of course) and all my fluids are fine. A little shudder happened yesterday in drive, but shifted immediately back to park and back to drive and the shudder tapered off. Other than that. She's fine. Sorry...back to my original question. What causes headgasket failure on the 97-99 northstars?

02-16-12, 11:58 AM
Go up to the stickys at the top of this forum and wade through the headgasket threads. There are several schools of thought - head bolt(s) lose clamping force due to: block thread corrosion from poor casting methods, block thread corrosion caused by coolant intrusion, block thread failure due to fine threads in aluminum; all sorts of scenarios, and none radically different than what has caused head gasket failure in many, many other engines over the years. NO automotive engine is exempt from head gasket failure, regardless of manufacturer, and you can verify that by lurking in any other automotive forum on the internet.

One possibly preventive ritual is to change the coolant (DEX-COOL or green) religiously every 3 years.

I was replacing head gaskets on Jaguars, Austin-Healeys, Datsuns and MG's in the late 50's - head gasket failure is not all that uncommon.

02-16-12, 12:56 PM
I just pray mine won't die on me. It's my first car, so I plan on babying it. Except when I'm on the highway :).

02-16-12, 02:31 PM
Drive it like you stole it. The Northstar engine likes to run. My car is 10 years old and just did a run to 126 yesterday: not a problem.

N*caddy has a '97 STS and did a non-stop circuit of the U.S - almost 11,000 miles - last year with no trouble.

02-16-12, 02:52 PM
Yes - all of what Sub said - based on my experiences and observations, I favor block thread corrosion caused by coolant intrusion as the most common and most likely explanation. When I did mine, I found totally failed (head bolts didn't catch at all) wet block threads, wet failing block threads, wet, but still good threads (bolts "snapped" when loosened, and threads that were dry and perfectly fine. I think these showed the natural progression, from good to bad, that takes place. I think the reason the threads basically dissolve away is the combination of coolant, steel bolts, an aluminum black, lots of heat and also corrosive combustion gases

02-18-12, 04:36 AM
1. Block thread failure due to reasons stated above
2. Gasket failure due to failure of corrosion inhibitor in coolant / or lack of maintenance