The new gaskets are fine. Just make sure you get them at a
dealer and follow the directions that come with the gasket.
After market gaskets, your asking for trouble.

If they have not been replaced.........they need to be replaced. OEM first Fel-Pro fine though.

I've had similar experience with Chevy's 2.8 L. V6 (similar in design to the 3.1 L V6) Had two of the 2.8 L engines. Intake manifolds leaked around 70,000 miles. The manifold bolts were not tight, just a little past finger tight. Something relaxes on these after assembly and with use. I attributed this to thermal cycling. Otherwise, these were fine little V6 s. One of the manifolds had an undected air leak leaning out cylinder no. 1 and damaged it causing shortened engine life. The other manifold dumped coolant onto the engine pan.

My advice is to re-torque the intake bolts after new gaskets have been installed, and the engine has been thermal cycled a few times, like a week's use. Use the manufacturer's recommended tightening pattern. On re-torquing, tighten only 1/4 turn at a time per bolt. You may have to go through the bolt pattern 5 or more times to complete the job.

Sometimes O.E. isn't the way to go kalining. The aftermarket researched this failure, and there is a revised gasket that addresses this problem that was available in the aftermarket before it became the updated gasket you now see in the dealer.....

For those that may want to do this service yourself, make sure to use the revised torque specs, and you definately need to use thread locker to maintain torque on the bolts. Plus the most common error someone new to this engine makes is mixing up the pushrods. There are different length pushrods, and mixing them up will result in bent valves! So be carefull, or leave it to a pro.

Had a 96 corsica and could not get after market gasket for the manifold.Had to go to the dealer. The car was too new. They had the new change up. Yes you need lock tite on the bolts. Some are as low as 10 lbs. ( 3.1 ). Unequal push rod lengths are usually on a roller cam, G.M. Ford is still almost normal. The 3.8 anyway.

send me anything you got about changing intake manifold gasket on 3.1 litre gm engine please.

"Sometimes O.E. isn't the way to go..."

Ditto! This is one of the rare examples where aftermarket quality usually is superior to O.E.

BTW, ain't GM's Dexcool grand? I hate that stuff although if your vehicle originally came with it (96 and newer GMs), I strongly suggest AGAINST switching to the conventional type (green) coolant/antifreeze. Not to get into a chemistry lesson here, but it will do more damage than good.

Hey Guys: I have Dexcool A/F in my 96 Riviera and 03 Malibu. I didn't know there was a problem with the stuff until I read the latest thread. Whats the issue with this coolant and is there anything a guy can do do remedy it? My Riviera has been pretty well trouble free since I bought it new 10 years ago and I'd like to keep it another 10 years. What can I do to minimize the problem that is still unknown to me? Also: On the manifild issue: I have the 3.1 in my 03 Malibu which has been trouble free until a stall problem occurred last week. Should I have the manifold bolts retorqued to help prevent the gasket problems mentioned on this thread? Is the problem still present in the newer Malibu's?
Thanks a lot.

Bucky, IMO, the best thing you can do is to keep the coolant at maximum full level at all times. It has been my experience that when Dexcool gets low and mixes with air for an extended period of time, it becomes really nasty and gunky. Also, although the extended coolants are suppose to go 100,000+ miles, I think you would be best served to flush and refill the system a little more frequently than that.

Some of the intake manifold bolts are easier to access than others. I do not advise retorquing retorquing the easy bolts and not the others as this may actually put more uneven pressure on the gasket and potentially cause a leak. I do not see any benefits in spending the time and/or money to simply retorque the intake manifold bolts because of accessability issues. Once you get to them you might as well take the few additional steps (removing valve covers, rocker arms, pushrods, intake, etc.) and go ahead and replace the gaskets.

semper fi: Thanks for the reply. What you advise on the bolt torque ? make sense. Also: I have learned that part of the dexcool sludging problem has been caused by bad or loose coolant reservior or rad caps. Apparently the original GM coolant caps are failure prone so its recommended to check them periodically or replace with oem part. Bad caps let air into the system which as you say in an enemy to dexcool. I just checked both of my GM dexcooled vehicles and all seems to be okay. Coolant is red and clear with no sludge noticeable or no buildup on the coolant caps. I intend to flush and replace coolant at 50 thou miles. Thanks again for the wisdom and advise on this subject. Bucky

has anyone used thermo gasket?how well does it work?

Don't forget to bleed the air from the cooling system after filling. It is located on top of the water pump housing. And flush the cooling system with distilled water only. Tap will also cause it start to gunk up too. And be sure the cooling fans work. Relays and fuses are not always the issue. Mine had an open circut to the pcm and caused the cooling fans not to work and started to overheat and cause the intake manifold problem. Those gaskets are like rubber bands and are sensitive to the overheat problem. Dex cool works great. I use it on all my diesels and helps last the engines longer. Cat antifreeze is the pretty close to dex cool.