Northstar Engines and System Technical Discussion Discussion, The InFamous N* Oil Leak - Oil Manifold in Cadillac Engine Technical Discussion; What did the factory do to solve this?
When did they do this?
What is then difference of factory solving
The InFamous N* oil leak in the oil manifold is in the upper part of
the plate between oil pan and the crankcase - thought everyone here
knew this. And the leak is on the upper part of this plate - why this
is a bad contruction from the beginning I don't know.
I don't believe that GM "solved" the potential problem during the production run - up to at least ? 2004 ? - after that, a TSB (Technical Service Bulletin) was issued outlining new oil pan and halfcase re-seal procedures using the then-new GM Gray RTV sealant - Permatex UltraGray.
I think that Jake or Evrett at NorthstarPerformance have quite a bit of insight here - they were involved in remaining stock purchase at the closing of the Livonia engine assembly plant. Many posts and pictures on this a few years ago.
Very specific seal procedures without using the original silicone seals. The new oil distribution manifold incorporates a new seal.
........... and it's not an infamous leak because many - the majority - Northstars do not have halfcase or oil pan seam leaks.
All Northstars will have oil leaks at a certain point in time. It's inevitable. In 04 they really screwed up and stopped machining the half case seal groove right up to the rear main seal area... there's about 3/8" of area without any seal. I'm surprised they don't leak more.
Essentially there are certain things you can do to extend the time before seepage will occur from a total re-seal. It involves careful surface preparation and the use of both rubber seals and RTV.
Sub you're close, but it's not Permatex Ultra Grey to my knowledge. the GM sealant is quite a bit thicker (if you don't have a pneumatic/electric sealant gun it sure gives your arm muslces a workout squeezing the trigger).
I will catch up a bit more tomorrow with all of this.
I had my (allante 1993 which leaked when I bought it with 67,000 milage
and 6 years of age) Engine out and resealed (and heads done) at slightly
more than 100,000 milage - I didn't have the manifold plate changed but
resealed with black loctite Quick gasket - the original o-ring gasket was
not broken or something - leak was because of flatness - so it was kept
and resealing was made all around and outside this o-ring gasket.