According to the book, "How to Rebuild Your GM V6 60 Degree Engine":
"The 60 degree V-6 uses gaskets for sealing the sides of the manifold to the heads, and RTV sealer at the front and back. As long as the sides of the intake manifold and their mating surfaces on the heads are clean of debris [and oil], you shouldn't have any sealing problems."
When installing intake manifold gaskets, make sure you have left and right properly identified (if so marked - not all gaskets are side-sensitive) and the correct side up (will be marked TOP or UP.) Also ...
"...you'll find you can't situate the gaskets totally against the heads because the pushrods are in the way. So you need to cut the gaskets that are touching the pushrods. Cut only the top bridging, not the bottom."
"When the gaskets are "modified" [bridging cut] lay them against the heads. If any portion of the gaskets hangs into the ports in the heads, take a pencil and draw the correct shape on the gaskets. Then remove the gaskets and trim them as necessary."
Now clean all mating surfaces with brake cleaner to make them absolutely clean.
"Now run a 3/16" bead of RTV sealer along the front and rear mating surfaces of the block, and up under the front and rear tabs of both intake manifold gaskets about 1/4 inch...Work carefully to make sure that there are no breaks in the sealer, but don't take too long or the RTV will begin to set. Whatever you do, don't use too much RTV sealer between the block and intake manifold, as it may be squeezed out from the joint and could end up circulating around the engine."
I think paulmckibben misunderstood, thinking that you were dealing with the lower intake manifold. For the intermediate and upper plenum halves, you should use the proper gaskets, they're available in an inexpensive kit ($15) for the upper intake tract. You can smear some RTV on them but it isn't necessary... I've rebuilt many 2.8's and never used RTV on the gaskets. If you decide to do otherwise, just make sure you use an O2 sensor-safe RTV.
By accident I found a vacuum leak in the gasket between middle and lower intake on my V6. Bolts were torqued correctly, but had the leak. I think I'll use a little RTV on them this time.
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10:29 AM
fierosound Member
Posts: 15217 From: Calgary, Canada Registered: Nov 1999
I cut these out of gasket material just for that reason - I don't want the whole set. A roll of gasket material, a sharpie and an xacto knife and voila you have 20 sets!
That's true also, I don't need a complete intake gasket set. I was thinking of trying "Permatex the Right Stuff" to seal the upper intake to the lower (down by the injectors) and then using it on the plenum also. Also keeping in mind to make a nice neat job of it, not getting it in the ports.
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12:40 PM
fierosound Member
Posts: 15217 From: Calgary, Canada Registered: Nov 1999
I looked it up in my receipts but it appears to be a local retailer's part number. The parent company is called Great Sky, and the retailer is called Autosense 007. The part number 379.16315 includes the two gaskets between the upper and lower plenum halves, and the lower plenum to intake manifold gasket for $11.99. Apparently it fits V6 Jeeps with a 173 ci engine as well. Hope this helps.
