I'm a Newbie. I've tried to look through some of the threads on this topic...

I have a 1997 Bonneville SE 158Kmiles. It looses a little antifreeze but the oil seems to be fine... I haven't had an oil analysis done however.

I believe I have a VIN "K" engine... 3.8L (naturally asperated )
I definately need to replace the upper plenum. I haven't started to disassemble the thing yet.

I wanted to get suggestions from the guys who have been through this already.

Should I replace just the upper or the upper and lower? Can/Should I make this determination actually prior to the disassembly in order to minimize downtime, or should I wait until I take the lower out and check it over... What should I look for on the lower?

I feel that I might as well put in,.... "the good stuff / parts" if I have to go through all the trouble..... What are the "good parts "?

Any suggestions or references to threads that you guys think would be helpful would be appreciated.

Thanks,

Jack

definately change the lower intake gaskets if they have not been changed before.

Search for "upper intake manifold" or "UIM" and you'll find a boat load of information here.

And welcome!

And to answer your questions as CorvetteCrazy did...

yes replace the upper intake manifold
Yes replace the lower intake manifold gaskets only

The magic word for the UIM is "Dorman"...

oh and .... 89 INCH pounds..not 1 more. (I learned the hard way I guess)

Yep. Or, you can contact Bob Dillon and have him send you a sleeved upper intake manifold. Search for posts by him to find out all the details behind his theory. I'm running one of his and have had no issues in 16,000 miles or so....

You rang?

Got a sleeved one sitting out in the garage and one coming in shortly from 96LeSabre.

$30 plus freight, and your promise to ship yours back to me freight prepaid. :

And yes, change the lowers.

We should also mention that Felpro gaskets have performed well for the BC club members.
I think Vital and JR had theirs apart after some miles and found no wear at all.
Please chime in here if you will.