If you go as far as replacing the upper intake, you may as well take the extra half hour and replace the lower intake gaskets, which have also been redesigned and improved.
Yeah, too late there though (but I do thank you for the advice, the last part is not directed at you by any means, your advice was great, my timing was late getting it is all)... I now know a lot more after reading about the Dex-Cool Settlement (deadline was late 2008), and that it is way too late to file for, especially after the settlement was entered into, then GM filed for bankruptcy, paid only 30% on any outstanding claims for these issues, even if timely filed (even though the money was fully set aside to pay settlement claims, they still counted the deposit as GM assets), in the bankruptcy, if that, then became rebranded Government Motors (the new GM). Same lemon company as the old GM.
See www(dot)dexcoolsettlement(dot)com for those with these same problems. Replace the (dot)'s with periods of course. You'll know what to expect & why if you read the settlement docs.
The car now runs just fine with no more leaks or further damage felt, seen or heard... but after putting it all back together, I still had an external coolant leak at the heater bypass plastic 90 from the lower manifold to the right side of the belt tensioner (stupid $4.00 plastic Dorman Help part at Auto Zone, but they also use the silicone "O" rings too), and another hour's labor to again remove the alternator and the heater bypass / belt tensioner with 3 easy bolts / pry out the 2 ends of the broken plastic 90 from really smooth bores very carefully, clean the 3 bores up properly, & replace the 90 (used a small amount of Vaseline to ease the inserting of the "O" rings, and reinstalled all and filter the new coolant captured in drain pans/refill system, and that was all done after filling and running with fresh coolant and an engine cleaning (after the upper manifold replacement), to even be able to find the small leak, so it is all fully repaired now.
But that still won't stop the dreaded Dex-Cool miracle coolant from attacking those new silicone gaskets, and the Dex-Cool coolant from sludging up in the future too to boot, so I will flush the system regularly to keep the coolant fairly fresh if I see it sludging up at all again.
I will also replace the throttle body end gasket occasionally I think, and check the manifold and throttle body bolt torque valves during each oil change maintenance cycle too now (they sure didn't have 89" lbs. on them when I removed them anymore, and I bought that $50.00 torque wrench loaner tool to add to the tool box, just to do so now), that is where most of the coolant sucked into the manifold from it appeared to me, was at the lower edge of the throttle body, and the EGR tube is a great improvement in the new plenum.
Hope this info helps others. I know one thing though, I own 2 GM cars right now... I will never buy another one in my lifetime, not new, not used. Nor will my family members (and I will talk a lot about this experience to many others)... SCREW YOU Government Motors... You have lost a lifetime customer.
This Dex-Cool / silicone gasket / plastic cooling parts issue should have been a safety recalled item at the very least... Possible and probable hydrolocking of the combustion cylinders (cylinder #6 in my case and entire upper intake flooded, lucky though, no coolant in the oil, others were not so lucky I have read and seen on YouTube), isn't just possibly very expensive, it can be downright absolutely dangerous during driving conditions (mine started to happened on a 75 mph highway off ramp, it actually hydrolocked right after parking the car, luckily as my son was driving, & my wife & other people's kids from school were in the car too).
And GM, YOU KNEW THIS NASTY DESIGN ISSUE EXISTED on millions of cars. 53,000 attorney hours went into that Dex-Cool GM class action suit, you settled, but you knowingly screwed all the rest of us and stuck us with your Government Motors lemons... Dex-Cool was your special miracle lemonade... Then you walked away from ALL OF US except a lucky few. And then filed bankruptcy on many of those lucky few with claims outstanding then.
Then to top it off, you took our taxpayer bailout $$$ to twist that knife a little more and much deeper, as we out here are stuck with your lemons and that miracle GM Dex-Cool lemonade.
Can anyone here tell I'm a lil' ticked off. Sorry all, I know many of you have the very same issues... We are all just screwed now... The only thing we can do now is vent after the class settlement, try to stem the tide before problems develop, or after the repairs are done increase & add to our maintenance routine, and OF COURSE, swear off buying anything ever again from Government Motors (GM)... and tell plenty of others about our experiences with this Dex-Cool/GM issue.
Talk often, TALK LOUD... let others know (all the affected GM LEMON cars are listed in the settlement docs and the link is above)... I WILL TELL EVERYONE I KNOW WHO OWNS ONE of those affected lemons, just what they can expect, and why now.
Take care all.
And thank you CSDO Media Limited for the CarSurvey.org website and for posting my comments.
I appreciate you allowing us to tell the truth and inform others of this type of car issue. Without this site, I would still be looking at the starter, Vatts II system, or ignition switch/harness for why the engine wouldn't crank when the starter would click, click, click away.
Thank you for the valuable advice. You're blessed to have the skill, but what would the approx cost be at a shop to install a plenum?