you could add a qt of oil to it once a month for the next 10 years and still not be even at 1/2 the cost to replace the seals
What did you do to your NNBS GMT900 Tahoe/Yukon Today?
- Thread starter phattyford
- Start date
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My problem is I have to add 1 qt a week. More in the summer running the AC and stressing it.
still way ahead of the game, just buy in bulk and bump it up a viscosity
Charlie207
Full Access Member
If it were me I'd swap the valve seals with the heads on the engine using this technique. Looks easy.
Might as well swap in some LS3 or BTR valve springs for your cam upgrade while you're in there.
I have seen some really bad valve guide seals, but enough to use a quart of oil is a lot. I think you'd have killed. the o2s and cats pretty quickly since it's not being burnt in the cyl?
but yeah, seals are definitely doable in the car
but yeah, seals are definitely doable in the car
Charlie207
Full Access Member
Might as well pop out that unmonitored CA-only 3rd cat. while you're checking if it's clogged.
90 persent of it is leaking out the rear main and pan. The top end on this is so wore out I ain't wasting any time to put seals on it. Just gonna run it until a lifter takes a sh*t and replace the whole motor with a new unit. I got the money for it but now I don't think my mechanic has the time until over the winter. See what happens. I cringe from the lifter noise every time I cold start this thing after it sits overnight and the oil drains down.
mikez71
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A FRIEND of mine says he liked the quieter sound WITH the 3rd cat, and he doesn't notice anymore power with it removed.
Whatever would clog the 3rd cat, would have first clogged the manifold cats. (unless the manifold cats broke apart)
Charlie207
Full Access Member
Allegedly there was a 5hp rating loss when they added the 3rd cat.
Never fails 
