Hi, I've looked around and found info on failures for the northstar4.6 after 100K miles specifically at 122K but is there anybody with lots of miles on them and good stories about this engine?

They are hard to work on, and head gaskets fail around 100k. That is all I know of.

There have been some high mileage examples, however I believe them to be the exception rather than the rule.

I see it like this:

Worry free window closes about 120k miles
End of life is usually caused by a mechanical failure around 200k miles

The benefits are the power they make and the noise they make doing it.

Drawbacks include fuel economy, lack of accessibility, etc.


Compared to the 3.8, which is notorious for running until it drops dead (excluding LIM/UIM casualties), which is usually long after the transmission has exploded, and the body has rattled (or rusted) itself to pieces.

What he ^^ said.

Best info and many thanks

I also want to add, if you can get headgasket issues addressed, or know that they have already been addressed permanently, 122k miles probably still has life left in it. If not, it'* a ticking time bomb.

What appears to happen the head gaskets start to leak then in some cases they leak coolant into the combustion chamber and because water wont compress they rip the threads out of the block
O there is a fix called timserts were you drill the block and tap it out bigger
and tread in a insert with threads on out side and inside
best left up to a machine shop on a bare block
And who is to say it wont happen again
Lets just say the aluminum in a beer can is better quality then
the block is made of
Did we say anything about were you have to remove the engine to get the heads off
or the oil pan in the sub block
And lets not forget when your wife calls you saying the starter is dead
and you think {no big deal I will change it at her work right!!}
GM'* idea was {hey how can we screw every one from working on this more then we all ready have}
I know we can put the starter under the intake manifold
the only people that still have one soon finds out there life savings are gone
paying some one to fix it

just call me slow, first head gasket at 122K, then about 153K, then last time 157K. Now have about 187K which seems to be ok for now (and yes studs were in place of OEM bolts or timeserts). I do mostly Hwy driving to about 35K a year otherwise seems reliable if you can keep the head gasket sealed! Just normal maintenance otherwise. Hwy MPG 25-27 flat road and NO head winds (maybe a tail wind though).

SO pull motor at 122k then 31k later pull motor again then pull motor again 4k later again
so what was the charge about $2000 each time for $6000 total?
One replacement lasted 4 thousand miles ?
Well its like a early British car you can watch your bank account drain to nothing
to keep it running

no...actually the work was done by reputable shop and the studs were from reputable source so all the work was done under warranty! Just appears to be poor design on the N* where was GM to stand behind the infamous product, about 20 years of a known problems which was just ignored. Lets call it like it is, GM had some bad products and to get around it they just applied marketing/commercials to the problems. I can never forget the Cadillac N* commercials.