I am starting this thread to address a common oil leak problem that often ends up needing service, especially since some of these Northstar engines are approaching 20+ years old.
The complaint / problem is usually oil leaking which eventually makes contact with the exhaust and smells, or at minimum leaks leaving oil stains in the driveway.
The fix can be rather expensive! Many times people will just replace the lower oil pan however this is not usually enough and the vehicle will still leak oil. The design of the Cadillac Northstar engine is such that there is really a 3 piece oil pan on these vehicles. The lower half is what many refer to as the oil pan, then there is the bedplate which is basically the engines main bearing caps and girdle to hold the crankshaft and bearings in. Sandwiched between that is another thin shim which makes the 3 piece pan.
The rubber gaskets that seal all three of these pans often times, with age, becomes flat, hard and no longer seals. Obviously this causes an oil leak while the vehicle is running. The proper fix requires the removal of the engine and lower half of the engine to re-seal.
These photos show in-order the 3 pieces being separated and the seals that leak.
But keep in mind if you are considering having this done, that just like the head bolts - the main bolts also like to break.
Should this happen you're looking at some serious problems and an overhaul is in your future because at that point, you may as well do it all the right way since there is no real way to "cheat" this..
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What is to give light must endure burning -- Viktor Frankl
That' is a lot of work to go through to fix an oil-leak LOL !
There's never any harm in measuring your crank-journals & slipping-in some new bearings whilst you're there...But I'm not sure a full-rebuild would be a viable thing to do mate...
There's a point where the money spent offers little-to-no-return for all the effort. But if you're going to keep it, why not ?...For a long-term winter-car, it may prove to be the right thing to do...
4.6 liters of DOHC & 32-valves wrapped in a V-8 package does have a smile-factor to enjoy, especially when the motor spins to 6,000-rpm in standard trim !
Good work, & good luck.
( NB. That "3-bond" sealant will ensure no more oil-leaks will ever happen again ! ).
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"Only an alert & knowledgeable citizenry can compel the proper meshing of the huge industrial & military machinery of defense with our peaceful methods & goals, so that security & liberty may prosper together". Dwight D.Eisenhower.
We will see how it all unfolds but it would be nice to drive the car for 10 years or if someone gave me $4,000 for it, I'd let it go... maybe a little less as the years passed but if sealed up and done right it would be a nice car. Having priced newer vehicles at $40,000+ for the type of vehicle I would buy I'd like to think this is just peanuts. Just a real bummer as this was more or less the "winter" car so I have to make a choice... I'd still clear $2800 if I just put the transmission in it since it's not really leaking much oil... it's just the amount of work to pull it back out to do it right later... And lets not beat around the bush, it's basically a re-build since these things are known for head gaskets anyway.
I'm better of stuffing the transmission in it and then rebuilding the one we have apart at my leisure. At least then there isn't a car down... Think that's the direction I will take since there is no way to cut corners when it comes to pulling that bedplate.
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What is to give light must endure burning -- Viktor Frankl
